CN118158590A

CN118158590A - Open type wearable acoustic equipment and active noise reduction method

Info

Publication number: CN118158590A
Application number: CN202211563261.5A
Authority: CN
Inventors: 张承乾; 郑金波
Original assignee: Shenzhen Voxtech Co Ltd
Current assignee: Shenzhen Voxtech Co Ltd
Filing date: 2022-12-07
Publication date: 2024-06-07

Abstract

The application provides an open type wearable acoustic device and an active noise reduction method. The first sound signals collected by the first sound sensor module comprise an environmental noise signal from environmental noise and a leakage signal from a loudspeaker. The noise reduction circuit may generate the quasi-ambient noise signal by first reducing a component of the leakage signal in the first sound signal and then generate the first noise cancellation signal based on the quasi-ambient noise signal. And the loudspeaker converts the first noise elimination signal into first noise elimination audio frequency, so that the first noise elimination audio frequency is offset with at least partial environmental noise in the eardrum and nearby space, and the purpose of noise reduction is achieved. The noise reduction circuit reduces the components of the leakage signal in the first sound signal in the feedforward noise reduction process, and reduces the influence of the leakage signal on feedforward noise reduction, so that the noise reduction effect of active noise reduction can be improved.

Description

Open type wearable acoustic equipment and active noise reduction method

Technical Field

The present disclosure relates to the field of audio technologies, and in particular, to an open wearable acoustic device and an active noise reduction method.

Background

Nowadays, wearable devices (e.g. headphones) with acoustic output capabilities are used by more and more users. In particular, a listening mode in which an acoustic device does not form a closed space with a human body (i.e., a listening mode in which an ear is opened, for example, there is no need to plug the acoustic device into an ear canal or cover the ear, or a surface of the acoustic device is provided with a sound-transmitting hole so that an open space is formed between an eardrum and the acoustic device), has been increasingly used in wearable acoustic devices because of its characteristics of comfort, safety, and the like. Such wearable acoustic devices are referred to as open wearable devices.

The open wearable acoustic device is worn on the head of the user, and therefore, a closed space is not formed between the open wearable acoustic device and the eardrum of the user, so that compared with the closed acoustic device (such as an in-ear earphone, etc.), sound emitted by a noise source outside the ear can enter the ear more, so that the user can hear more environmental noise when wearing the open acoustic device, and the hearing experience of the user is reduced. Accordingly, there is a need to provide an active noise reduction design based on an open wearable acoustic device.

Disclosure of Invention

The specification provides an open wearable acoustic device and an active noise reduction method, which can improve the active noise reduction effect.

In a first aspect, the present description provides an open wearable acoustic device comprising: a support, a speaker, a first sound sensor module, and a noise reduction circuit, wherein the speaker is physically connected to the support, forming an open space between the speaker and the eardrum of a user when the acoustic device is worn on the user's head; a first sound sensor module is physically connected with the support and configured to collect a first sound and generate a first sound signal comprising: an ambient noise signal from ambient noise and a leakage signal from the speaker; the noise reduction circuit is configured to: the method includes the steps of obtaining a first sound signal from the first sound sensor module, generating a quasi-ambient noise signal by reducing components of the leakage signal in the first sound signal, generating a first noise cancellation signal based on the quasi-ambient noise signal, and sending the first noise cancellation signal to the loudspeaker so that the loudspeaker converts the first noise cancellation signal into first noise cancellation audio to reduce the volume of ambient noise at the eardrum.

In some embodiments, the first acoustic sensor module is remote from the eardrum relative to the speaker, and the phase of the ambient noise reaching the first acoustic sensor module leads the phase of the ambient noise reaching the sound outlet end of the speaker.

In some embodiments, to generate the quasi-ambient noise signal, the noise reduction circuit: acquiring an input signal corresponding to the loudspeaker; providing a first gain for the input signal to obtain a first gain signal, wherein the first gain is a transfer function between the loudspeaker and the first sound sensor module; and obtaining the first sound signal from the first sound sensor module, and subtracting the first gain signal from the first sound signal to obtain the quasi-environmental noise signal.

In some embodiments, the noise reduction circuit is further configured to: transmitting a test audio signal to the loudspeaker so that the loudspeaker emits corresponding test audio, wherein the test audio is collected by the first sound sensor module; acquiring an acquired audio signal acquired by the first sound sensor module; and determining the transfer function from the test audio signal and the acquired audio signal.

In some embodiments, a feedforward filter is included in the noise reduction circuit, wherein to generate the first noise cancellation signal, the noise reduction circuit: the quasi-ambient noise signal is input into the feedforward filter, and the quasi-ambient noise signal is filtered through the feedforward filter to obtain the first noise cancellation signal, wherein the feedforward filter is configured to adjust at least one of gain or phase of the quasi-ambient noise signal so that the obtained first noise cancellation signal can offset at least part of ambient noise at the eardrum.

In some embodiments, the distance between the first sound sensor module and the acoustic zero position of the speaker is within a non-zero preset range.

In some embodiments, the acoustic device further comprises a second sound sensor module physically connected to the support and configured to collect a second sound signal and generate a second sound signal; and the noise reduction circuit is further configured to: the method includes obtaining the second sound signal from the second sound sensor module, generating a second noise cancellation signal based on the second sound signal, and transmitting the second noise cancellation signal to the speaker to cause the speaker to convert the second noise cancellation signal to second noise cancellation audio to further reduce the volume of ambient noise at the eardrum.

In some embodiments, the second sound sensor module is proximate to the eardrum relative to the speaker, and the phase of the ambient noise reaching the second sound sensor module is later than the phase of the ambient noise reaching the sound outlet end of the speaker.

In some embodiments, to send the first and second noise cancellation signals to the speaker, the noise reduction circuit: synthesizing the first noise elimination signal and the second noise elimination signal to obtain a synthesized noise elimination signal; and sending the synthesized noise cancellation signal to the speaker.

In some embodiments, a feedback filter is included in the noise reduction circuit, wherein to generate the second noise cancellation signal, the noise reduction circuit: inputting the second sound signal into the feedback filter; and filtering the second sound signal through the feedback filter to obtain the second noise cancellation signal, wherein the feedback filter is configured to adjust at least one of a gain or a phase of the second sound signal so that the obtained second sound signal can be offset with at least part of ambient noise at the eardrum.

In some embodiments, the noise reduction circuit comprises: at least one storage medium storing at least one set of instructions for performing noise reduction, and at least one processor; the processor is in communication with the speaker, the first acoustic sensor module, and the at least one storage medium, wherein the at least one processor reads the at least one instruction set and performs, upon indication of the at least one instruction set, when the acoustic device is operating: the method includes obtaining the first sound signal from the first sound sensor, generating a quasi-ambient noise signal by clipping a component of the leakage signal in the first sound signal, generating a first noise cancellation signal based on the quasi-ambient noise signal, and transmitting the first noise cancellation signal to the speaker to cause the speaker to convert the first noise cancellation signal to a first noise cancellation audio to reduce a volume of ambient noise at the eardrum.

In some embodiments, the acoustic device is one of an earpiece, a muffler, a hearing aid, and an acoustic glasses.

In a second aspect, the present specification also provides an active noise reduction method applied to the open wearable acoustic device of the first aspect, the method comprising, by noise reduction circuitry: acquiring the first sound signal from the first sound sensor module; generating a quasi-ambient noise signal by clipping a component of the leakage signal in the first sound signal; generating a first noise cancellation signal based on the quasi-ambient noise signal; and sending the first noise cancellation signal to the speaker to cause the speaker to convert the first noise cancellation signal to first noise cancellation audio to reduce the volume of ambient noise at the eardrum.

In some embodiments, the phase of the ambient noise measured by the first acoustic sensor module leads the phase of the ambient noise reaching the sound outlet of the speaker.

In some embodiments, the generating a quasi-ambient noise signal by clipping a component of the leakage signal in the first sound signal comprises: acquiring an input signal corresponding to the loudspeaker; providing a first gain for the input signal to obtain a first gain signal, wherein the first gain is a transfer function between the loudspeaker and the first sound sensor module; and obtaining the first sound signal from the first sound sensor module, and subtracting the first gain signal from the first sound signal to obtain the quasi-environmental noise signal.

In some embodiments, the method further comprises, by the noise reduction circuit: transmitting a test audio signal to the loudspeaker so that the loudspeaker emits corresponding test audio, wherein the test audio is collected by the first sound sensor module; acquiring an acquired audio signal acquired by the first sound sensor module; and determining the transfer function from the test audio signal and the acquired audio signal.

In some embodiments, a feedforward filter is included in the noise reduction circuit; and generating a first noise cancellation signal based on the quasi-ambient noise signal, comprising: the quasi-ambient noise signal is input into the feedforward filter, and the quasi-ambient noise signal is filtered through the feedforward filter to obtain the first noise cancellation signal, wherein the feedforward filter is configured to adjust at least one of gain or phase of the quasi-ambient noise signal so that the obtained first noise cancellation signal can offset at least part of ambient noise at the eardrum.

In some embodiments, the acoustic device further comprises a second sound sensor module physically connected to the support and configured to collect a second sound signal and generate a second sound signal; and the method further comprises, by the noise reduction circuit: the method includes obtaining the second sound signal from the second sound sensor module, generating a second noise cancellation signal based on the second sound signal, and transmitting the second noise cancellation signal to the speaker to cause the speaker to convert the second noise cancellation signal to second noise cancellation audio to further reduce the volume of ambient noise at the eardrum.

In some embodiments, the phase of the ambient noise measured by the second sound sensor module is later than the phase of the ambient noise reaching the sound outlet of the speaker.

In some embodiments, a feedback filter is included in the noise reduction circuit; and generating a second noise cancellation signal based on the second sound signal, comprising: inputting the second sound signal into the feedback filter, and filtering the second sound signal through the feedback filter to obtain the second noise cancellation signal, wherein the feedback filter is configured to adjust at least one of a gain or a phase of the second sound signal, so that the obtained second noise cancellation signal can offset at least part of environmental noise at the eardrum.

According to the technical scheme, the open type wearable acoustic device and the active noise reduction method provided by the specification comprise a first sound sensor module, a loudspeaker and a noise reduction circuit. The first sound signals collected by the first sound sensor module comprise an environmental noise signal from environmental noise and a leakage signal from a loudspeaker. The noise reduction circuit may generate the quasi-ambient noise signal by first reducing a component of the leakage signal in the first sound signal and then generate the first noise cancellation signal based on the quasi-ambient noise signal. And the loudspeaker converts the first noise elimination signal into first noise elimination audio frequency, so that the first noise elimination audio frequency is offset with at least partial environmental noise in the eardrum and nearby space, and the purpose of noise reduction is achieved. The noise reduction circuit reduces the components of the leakage signal in the first sound signal in the feedforward noise reduction process, and reduces the influence of the leakage signal on feedforward noise reduction, so that the noise reduction effect of active noise reduction can be improved.

Additional functionality of the open wearable acoustic device and active noise reduction method provided in this specification will be set forth in part in the description that follows. The inventive aspects of the open wearable acoustic devices and active noise reduction methods provided herein may be fully explained by practicing or using the methods, apparatuses, and combinations described in the following detailed examples.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present description, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present description, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1A shows a schematic view of a wearing scenario of an acoustic device provided according to an embodiment of the present description;

FIG. 1B shows a schematic diagram of an acoustic device in an in-ear wearing mode;

FIG. 1C shows a schematic diagram of an acoustic device in the form of a hanger wear;

FIG. 1D shows a schematic diagram of an acoustic device in the form of a clip-on wearing;

Fig. 2 shows a schematic hardware structure of an acoustic device according to an embodiment of the present disclosure;

FIG. 3 shows a schematic view of leakage signals acquired by sound sensors at different locations in an acoustic device;

FIG. 4 illustrates a flow chart of an active noise reduction method provided in accordance with an embodiment of the present disclosure;

FIG. 5 illustrates a schematic diagram of the active noise reduction principle of an acoustic device provided in accordance with an embodiment of the present disclosure;

FIG. 6 illustrates a schematic diagram of the noise reduction effect of an active noise reduction method provided in accordance with an embodiment of the present disclosure;

FIG. 7 illustrates a flow chart of another active noise reduction method provided in accordance with an embodiment of the present disclosure;

FIG. 8A is a schematic diagram showing a frequency response curve for feedforward noise reduction of ambient noise at the eardrum with different feedforward filter gains with an acoustic device worn by a first user;

FIG. 8B is a schematic diagram showing a frequency response curve for feedforward noise reduction of a second sound signal with different feedforward filter gains with an acoustic device worn by a first user;

FIG. 9A is a schematic diagram showing a frequency response curve for feedforward noise reduction of ambient noise at the eardrum with different feedforward filter gains with the acoustic device worn by a second user;

FIG. 9B is a schematic diagram showing a frequency response curve for feedforward noise reduction of a second sound signal with different feedforward filtering gains with an acoustic device worn by a second user;

FIG. 10 is a schematic diagram showing the distribution of each of the sound sensors in the case where 2 sound sensors are included in the first sound sensor module;

FIG. 11 is a schematic diagram showing the distribution of each of the sound sensors in the case where 3 sound sensors are included in the first sound sensor module;

FIG. 12 illustrates a flow chart of yet another active noise reduction method provided in accordance with an embodiment of the present disclosure;

FIG. 13 illustrates a schematic diagram of the active noise reduction principle of another acoustic device provided in accordance with an embodiment of the present disclosure;

FIG. 14 shows a schematic diagram of a set of frequency response curves provided in accordance with an embodiment of the present description;

FIG. 15 shows a schematic diagram of yet another set of frequency response curves provided in accordance with an embodiment of the present description; and

Fig. 16 shows a flow chart of yet another active noise reduction method provided in accordance with an embodiment of the present description.

Detailed Description

The following description is presented to enable one of ordinary skill in the art to make and use the invention, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the disclosure. Thus, the present description is not limited to the embodiments shown, but is to be accorded the widest scope consistent with the claims.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. For example, as used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. The terms "comprises," "comprising," "includes," and/or "including," when used in this specification, are taken to specify the presence of stated integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

These and other features of the present specification, as well as the operation and function of the related elements of structure, as well as the combination of parts and economies of manufacture, may be significantly improved upon in view of the following description. All of which form a part of this specification, reference is made to the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the description. It should also be understood that the drawings are not drawn to scale.

The flowcharts used in this specification illustrate operations implemented by systems according to some embodiments in this specification. It should be clearly understood that the operations of the flow diagrams may be implemented out of order. Rather, operations may be performed in reverse order or concurrently. Further, one or more other operations may be added to the flowchart. One or more operations may be removed from the flowchart.

For convenience of description, terms appearing in the specification are explained first:

Closed acoustic device: some acoustic devices, which may be referred to as closed acoustic devices, form an enclosed space between the acoustic device and the eardrum of the user in the worn state. For example, the acoustic device may be in an in-ear design (e.g., an ear bud earphone), a closed ear cup design, or other similar designs that create an enclosed space with the eardrum of the user. When a user wears the closed acoustic equipment, the closed space can isolate external noise physically, and interference of the external noise to the user is reduced. But users often feel uncomfortable when wearing closed acoustic devices for a long period of time.

Open acoustic device: some acoustic devices, which may be referred to as open acoustic devices, form an open space between the acoustic device and the eardrum of the user when in a worn state. For example, the acoustic device may not be plugged into or over the ear canal, or the surface of the acoustic device may be provided with a sound-transmitting aperture such that an open space is formed between it and the eardrum. The open acoustic device can improve wearing comfort of a user and enable sound heard by the user to be more transparent and natural.

Noise: any sound that is not welcomed by the user, not intended by the user, or interferes with the user's hearing may be referred to as noise in the present application.

Passive noise reduction: may refer to techniques that employ passive means for noise reduction. Such passive means include, but are not limited to: cancel (or partially cancel) a noise source, block the propagation of noise, or block the user's ear from hearing noise, etc., or any combination thereof. For example, a technique of achieving noise reduction by forming an enclosed space in the ear belongs to a passive noise reduction technique. Passive noise reduction techniques may also be referred to as passive noise reduction techniques. Passive noise reduction does not eliminate noise, but rather suppresses noise by physical means.

Active noise reduction: may refer to techniques that actively reduce noise by generating a noise cancellation signal (e.g., a signal that is opposite in phase to the noise to be suppressed). Specifically, the acoustic device adopting the active noise reduction technology can collect noise signals through the sound sensor, generate a noise cancellation signal for canceling the noise signals through the noise reduction circuit, and play the noise cancellation signal through the loudspeaker, so that the noise cancellation signal is offset with the noise signals, and noise is eliminated. Active noise reduction techniques may also be referred to as active noise reduction techniques. Active noise reduction techniques can be categorized into feed-forward noise reduction, feedback noise reduction, and hybrid noise reduction.

Feedforward noise reduction: and placing a sound sensor on the outer side of the acoustic equipment, collecting environmental noise through the sound sensor, generating an environmental noise signal, filtering the environmental noise signal through a feedforward filter to generate a noise elimination signal, and playing the noise elimination signal through a loudspeaker. In this way, the noise cancellation signal cancels (or partially cancels) the ambient noise at the eardrum, thereby reducing the volume of the ambient noise heard by the user. The feedforward filter is mainly used for compensating the difference between the ambient noise at the eardrum and the ambient noise acquired by the sound sensor. In a feed-forward noise reduction system, an open loop noise reduction control system is formed between the speaker and the sound transducer.

Feedback noise reduction: and placing a sound sensor on the inner side of the acoustic equipment, collecting the environmental noise in the area near the eardrum through the sound sensor, filtering the environmental noise through a feedback filter to generate a noise elimination signal, and playing the noise elimination signal through a loudspeaker. In this way, the noise cancellation signal cancels (or partially cancels) the ambient noise at the eardrum, thereby reducing the volume of the ambient noise heard by the user. In a feedback noise reduction system, a closed loop noise reduction control system is formed between the speaker and the sound transducer.

Mixing and noise reduction: hybrid noise reduction refers to a technique that combines feedforward noise reduction and feedback noise reduction. Generally, hybrid noise reduction can further enhance noise reduction compared to feedforward noise reduction alone or feedback noise reduction alone.

The application provides an open type wearable acoustic device (hereinafter simply referred to as an acoustic device) and an active noise reduction method thereof, which can reduce the volume of environmental noise heard by a user and reduce the interference of the environmental noise to the user in a scene that the user wears the acoustic device.

Fig. 1A shows a schematic view of a wearing scenario of an acoustic device provided according to an embodiment of the present specification. In the scene 001, the acoustic device 100 is worn at the ear 200 of the user. The ear 200 may include, among other things, an auricle 201 and an eardrum 202. The acoustic device 100 may be worn at the auricle 201, and the acoustic device 100 is not closed with the eardrum 202, forming an open space. Noise source 300 may also be included in scene 001, and the number of noise sources 300 may be one or more. Noise source 300 is configured to emit ambient noise (e.g., sounds that are not welcome by the user, that are not intended by the user, or that interfere with the hearing of the user). The acoustic device 100 is configured to suppress or eliminate ambient noise audible to the human ear. Specifically, the acoustic device 100 suppresses or eliminates environmental noise by generating and outputting a noise cancellation signal (a signal opposite in phase to the environmental noise) in an active noise reduction manner.

In some embodiments, the acoustic device 100 may be an earphone, a muffler, a hearing aid, acoustic glasses, or the like, or any combination thereof. For ease of understanding, an acoustic device 100 is illustrated in fig. 1A as an example of a headset. When the acoustic device 100 is an acoustic glasses, the region of the temple of the acoustic glasses close to the ear may be provided with a sound output means configured to output sound to the ear of the user. The acoustic device 100 may be worn on the ear 200 of the user in any manner, which is not limited by the present application. For example, the wearing mode of the acoustic device 100 may include a head-wearing mode, an in-ear wearing mode, a neck-surrounding wearing mode, a hanging-on wearing mode, a ear-pinching wearing mode, or the like, or any combination thereof.

In some embodiments, scene 001 may further include: the network and the target device (not shown in fig. 1A). The target device may be an electronic device having an audio output function. The acoustic device 100 and the target device may be communicatively coupled via a network, and data or signals may be transmitted therebetween via the network. For example, the target device may send target audio (e.g., music, speech, etc.) to be played to the acoustic device 100 over a network for the acoustic device 100 to output the target audio to the user.

In some embodiments, the target device may be provided with an audio acquisition device, through which the target audio is acquired. In some embodiments, the target device may receive the target audio from other devices. In some embodiments, the target device may include a mobile device, a tablet, a notebook, a built-in device of a motor vehicle, or the like, or any combination thereof. In some embodiments, the mobile device may include a smart home device, a smart mobile device, a virtual reality device, an augmented reality device, or the like, or any combination thereof. In some embodiments, the smart home device may include a smart television, a desktop computer, a smart speaker, etc., or any combination. In some embodiments, the smart mobile device may include a smart phone, personal digital assistant, gaming device, navigation device, etc., or any combination thereof. In some embodiments, the virtual reality device or augmented reality device may include a virtual reality helmet, virtual reality glasses, virtual reality patch, augmented reality helmet, augmented reality glasses, augmented reality patch, or the like, or any combination thereof. For example, the virtual reality device or the augmented reality device may include *** glass, head mounted display, VR, or the like. In some embodiments, the built-in devices in the motor vehicle may include an on-board computer, an on-board television, and the like.

In some embodiments, the network may be any type of wireless network. For example, the network may include a telecommunications network, an intranet, the internet, a Local Area Network (LAN), a Wide Area Network (WAN), a Wireless Local Area Network (WLAN), a Metropolitan Area Network (MAN), a Wide Area Network (WAN), a Public Switched Telephone Network (PSTN), a bluetooth network, a ZigBee network, a Near Field Communication (NFC) network, or the like. In some embodiments, the network may be a bluetooth network, in which case communication between the acoustic device 100 and the target device may be based on the bluetooth (blue) protocol.

With continued reference to fig. 1A, the acoustic device 100 may include: a support 101, a speaker 102, a noise reduction circuit 105, and at least one sound sensor module. Wherein the speaker 102 and the at least one sound sensor module may each be physically connected to the support 101.

The support 101 may be used to assist in securing the acoustic device 100 to the user's ear. For example, the support 101 may be a housing or other additional structure of the acoustic device 100. The specific form of the support 101 is not limited in the present application. It should be appreciated that the specific configuration of the support 101 is related to the manner of wear supported by the acoustic device 100.

Fig. 1B shows a schematic diagram of an acoustic device in an in-ear wearing mode. In this case, the supporting member 101 may be designed to fit the auricle 201, and one or more supporting points on the supporting member 101 are fitted to preset points on the auricle 201. Fig. 1C shows a schematic view of an acoustic device in the form of a hanger wear. In this case, the support 101 may adopt a hanging structure so that the acoustic device 100 can be hung on the auricle 201. Fig. 1D shows a schematic view of an acoustic device in the form of a clip-on wearing. In this case, the support 101 may employ a clamping structure so that the support 101 can be clamped on the auricle 201.

With continued reference to fig. 1A, the speaker 102 may be disposed on a side of the acoustic device 100 proximate to the ear canal opening. When the acoustic device 100 is worn on the head of a user, an open space is formed between the speaker 102 and the eardrum 202 of the user. In some embodiments, when the acoustic device 100 is worn on the head of a user, the speaker 102 may be proximate to the ear canal orifice of the user and not occlude the ear canal orifice, thereby creating an open space between the speaker 102 and the eardrum 202. In some embodiments, the housing of the acoustic device 100 may be a non-enclosed housing, for example, with a sound-transmitting aperture disposed therein, such that an open space is formed between the speaker 102 and the eardrum 202.

The speaker 102 may be configured to generate audio based on the audio signal (or otherwise convert the audio signal to audio). The audio signal here is an electrical signal carrying sound information, and the audio signal refers to a sound signal played through a speaker. After sound is emitted from an original sound source (e.g., an environmental noise source, a person's throat, etc.), the sound is converted into an electrical signal carrying the sound information, i.e., the audio signal, via a sensor (e.g., a microphone) that collects the sound. The speaker 102 may also be referred to as an electroacoustic transducer and may be operable to receive the audio signal carrying the sound information and convert it to a sound signal for playback. In some embodiments, a plurality of speakers 102 may be included in the acoustic device 100. In this case, the plurality of speakers 102 may be arranged in an array, for example, a linear array, a planar array, a spherical array, or other arrays.

In some embodiments, the at least one acoustic sensor module may include a first acoustic sensor module 103. As shown in fig. 1A, the first acoustic sensor module 103 is remote from the eardrum 202 relative to the speaker 102. That is, the first sound sensor 103 may be provided outside the acoustic device 100 (the side of the acoustic device 100 away from the eardrum 202 is the outside when the acoustic device 100 is worn on the head of the user). In some embodiments, the first acoustic sensor module 103 may include one or more acoustic sensors. When the first acoustic sensor module 103 includes a plurality of acoustic sensors, the plurality of acoustic sensors may be arranged in an array, for example, a linear array, a planar array, a spherical array, or other array, etc. In some embodiments, the above-described sound sensor is a device for capturing sound and converting the sound into an electrical signal, such as a microphone.

In some embodiments, the at least one sound sensor module may include a second sound sensor module 104. The second sound sensor module 104 is proximate (or otherwise near) the eardrum 202 relative to the speaker 102. That is, the second sound sensor module 104 is disposed inside the acoustic device 100 (the side of the acoustic device 100 that is close to the eardrum 202 is the inside when the acoustic device 100 is worn on the head of the user). In some embodiments, the second sound sensor module 104 may include one or more sound sensors. When the second sound sensor module 104 includes a plurality of sound sensors, the plurality of sound sensors may be arranged in an array, for example, a linear array, a planar array, a spherical array, or other array, etc.

In some embodiments, the at least one acoustic sensor module may include both the first acoustic sensor module 103 and the second acoustic sensor module 104.

The first sound sensor module 103 is configured to collect a first sound and generate a first sound signal corresponding to the first sound. The first sound may be an analog sound signal, and the first sound signal may be an electrical signal. It should be appreciated that, due to the presence of noise source 300 in the environment in which acoustic device 100 is located, first sound sensor module 103 may collect the ambient noise emitted by noise source 300. In addition, since an open space is formed between the speaker 102 and the eardrum 202, the first sound sensor module 103 can also collect the sound emitted from the speaker 102. For convenience of description, the sound from the speaker 102 collected by the first sound sensor module 103 is referred to as a leakage sound in the present application. Accordingly, the first sound collected by the first sound sensor module 103 includes ambient noise and leakage sound. Accordingly, the first sound signal generated by the first sound sensor module 103 includes: an ambient noise signal from noise source 300 and a leakage signal from speaker 102.

The first sound sensor module 103 is remote from the eardrum 202 relative to the speaker 102, i.e. the first sound sensor module 103 is closer to the noise source 300 relative to the speaker 102. Therefore, the time when the ambient noise reaches the first sound sensor module 103 is earlier than the time when the ambient noise reaches the sound outlet end of the speaker 102. In other words, the phase of the ambient noise reaching the first sound sensor module 103 leads the phase of the ambient noise reaching the sound outlet of the speaker 102. Thus, the first acoustic signal collected by the first acoustic sensor module 103 may be used for feedforward noise reduction.

The second sound sensor module 104 is configured to collect a second sound and generate a second sound signal corresponding to the second sound. The second sound may be an analog sound signal, and the second sound signal may be an electrical signal. For an open acoustic device, the second sound sensor module 104 may collect, on the one hand, ambient noise emitted by the noise source 300 and, on the other hand, sound emitted by the speaker 102. Thus, the second sound collected by the second sound sensor module 104 includes a component of the ambient noise and a component of the sound emitted by the speaker 102. In the active noise reduction scenario, the environmental noise emitted by the noise source 300 reaches the open space along the air conduction, and a part of the environmental noise in the open space is offset or reduced by the sound of the speaker 102 in the active noise reduction process, so the second sound collected by the second sound sensor module 104 may also be referred to as residual noise, that is, the environmental noise still remaining in the open space.

The second sound sensor module 104 is proximate (near) the eardrum 202 with respect to the speaker 102, that is, the second sound sensor module 104 is farther from the noise source 300 with respect to the speaker 102. Thus, the moment when the ambient noise reaches the second sound sensor module 104 is later than the moment when the ambient noise reaches the sound outlet end of the speaker 102. In other words, the phase of the ambient noise reaching the second sound sensor module 104 is later than the phase of the ambient noise reaching the sound outlet of the speaker 102. Thus, the second sound signal collected by the second sound sensor module 104 may be used for feedback noise reduction.

With continued reference to fig. 1A, the noise reduction circuit 105 is connected to the first sound sensor module 103, the second sound sensor module 104, and the speaker 102 and is configured to perform active noise reduction to reduce the volume of ambient noise heard by the human ear. The active noise reduction may be any one of feedforward noise reduction, feedback noise reduction and hybrid noise reduction.

In some embodiments, the noise reduction circuit 105 may be configured to perform feed-forward noise reduction. In this case, the noise reduction circuit 105 may acquire the first sound signal from the first sound sensor module 103 and perform active noise reduction based on the first sound signal.

In some embodiments, the noise reduction circuit 105 may actively reduce noise based on the first sound signal may include: the noise reduction circuit 105 generates a first noise cancellation signal based on the first sound signal. The noise reduction circuit 105 transmits a first noise cancellation signal to the speaker 102 to cause the speaker 102 to convert the first noise cancellation signal into first noise cancellation audio. The phase of the first noise cancellation signal may be set to be opposite or approximately opposite or a preset phase difference from the phase of the ambient noise in the space at the eardrum 202, such that the phase of the first noise cancellation audio is opposite or approximately opposite to the phase of the ambient noise in the space at and near the eardrum 202, thereby reducing the volume of the ambient noise at the eardrum 202. In some embodiments, a feedforward filter may be included in the noise reduction circuit 105, connecting the first sound sensor module 103 and the speaker 102. After the noise reduction circuit 105 acquires the first sound signal from the first sound sensor 103, the first sound signal may be input to a feedforward filter, the first sound signal may be filtered by the feedforward filter to obtain a first noise cancellation signal, and the first noise cancellation signal may be output to the speaker 102. Wherein the feedforward filter is configured to adjust at least one of a gain or a phase of the first sound signal such that the resulting first noise cancellation signal is capable of being cancelled with at least a portion of the ambient noise at the eardrum 202.

In some embodiments, the noise reduction circuit 105 may also be configured to perform feedback noise reduction. In this case, the noise reduction circuit 105 may acquire the second sound signal from the second sound sensor module 104 and perform active noise reduction based on the second sound signal.

In some embodiments, the process of actively denoising the noise reduction circuit 105 based on the second sound signal may include: the noise reduction circuit 105 generates a second noise cancellation signal based on the second sound signal. The noise reduction circuit 105 transmits the second noise cancellation signal to the speaker 102 so that the speaker 102 converts the second noise cancellation signal into second noise cancellation audio. The second noise cancellation signal may be set to be opposite, approximately opposite, or a preset phase difference from the phase of the ambient noise at the eardrum 202 such that the phase of the second noise cancellation audio is opposite or approximately opposite to the phase of the ambient noise at the eardrum 202 and nearby spaces, thereby reducing the volume of the ambient noise at the eardrum 202. In some embodiments, a feedback filter may be included in the noise reduction circuit 105 connecting the second sound sensor module 103 and the speaker 102. After the noise reduction circuit 105 obtains the second sound signal from the second sound sensor 103, the second sound signal may be input to a feedback filter, the second sound signal may be filtered by the feedback filter to obtain a second noise cancellation signal, and the second noise cancellation signal may be output to the speaker 102. Wherein the feedback filter is configured to adjust at least one of a gain or a phase of the second sound signal such that the resulting second noise cancellation signal is capable of being offset with at least a portion of the ambient noise at the eardrum 202.

In some embodiments, the noise reduction circuit 105 may also be configured to perform hybrid noise reduction. In this case, the noise reduction circuit 105 may acquire the first sound signal from the first sound sensor module 103, acquire the second sound signal from the second sound sensor module 104, and perform active noise reduction based on the first sound signal and the second sound signal.

In some embodiments, the process of actively noise reducing by the noise reduction circuit 105 based on the first sound signal and the second sound signal may include: the noise reduction circuit 105 generates a first noise cancellation signal based on the first sound signal and generates a second noise cancellation signal based on the second sound signal. The noise reduction circuit 105 sends a first noise cancellation signal and a second noise cancellation signal to the speaker 102 to cause the speaker 102 to convert the first noise cancellation signal and the second noise cancellation signal into noise cancellation audio to reduce the volume of ambient noise at and near the eardrum 202. In some embodiments, a feedforward filter and a feedback filter may be included in noise reduction circuit 105. Wherein the feedforward filter connects the first acoustic sensor module 103 and the speaker 102. The feedback filter connects the second sound sensor module 104 and the speaker 102. The noise reduction circuit 105 may input the first sound signal into a feedforward filter, filter the first sound signal through the feedforward filter to obtain a first noise cancellation signal, input the second sound signal into a feedback filter, and filter the second sound signal through the feedback filter to obtain a second noise cancellation signal. The noise reduction circuit 105 in turn sends the first noise cancellation signal and the second noise cancellation signal to the speaker 102. Wherein the feedforward filter is configured to adjust at least one of a gain or a phase of the first sound signal such that audio produced by the resulting first noise cancellation signal after conversion by the speaker 102 is able to cancel out (i.e., phase of the audio is opposite or approximately opposite to) at least a portion of ambient noise at and near the eardrum 202. The feedback filter is configured to adjust at least one of the gain or phase of the second sound signal such that the resulting audio produced by the conversion of the first noise cancellation signal by the speaker 102 is able to cancel out at least a portion of the ambient noise at the eardrum 202 (i.e., the phase of the audio is opposite or approximately opposite to the phase of at least a portion of the ambient noise at the eardrum 202 and nearby space). In some embodiments, the noise reduction circuit 105 may send the first noise cancellation signal and the second noise cancellation signal, respectively, to the speaker 102. In some embodiments, the noise reduction circuit 105 may first synthesize the first noise reduction signal and the second noise reduction signal to obtain a synthesized noise reduction signal, and then send the synthesized noise reduction signal to the speaker 102.

In some embodiments, the noise reduction circuit 105 may be configured to perform the active noise reduction methods described herein. At this time, the noise reduction circuit 105 may store data or instructions to perform the active noise reduction method described in the present specification, and may execute or be used to execute the data or instructions. In some embodiments, the noise reduction circuit 105 may include a hardware device having a data information processing function and a program necessary to drive the hardware device to operate. The above-described active noise reduction method will be described in detail later.

Fig. 2 shows a schematic hardware structure of an acoustic device according to an embodiment of the present specification. As shown in fig. 2, in some embodiments, the noise reduction circuit 105 may include: at least one storage medium 106, and at least one processor 107. The at least one processor 107 is communicatively coupled to the speaker 102, the first acoustic sensor module 103, and the second acoustic sensor module 104. It should be noted that, for illustration purposes only, the noise reduction circuit 105 of the present application includes at least one storage medium 106 and at least one processor 107. Those of ordinary skill in the art (one of ordinary SKILL IN THE ART) will appreciate that the noise reduction circuit 105 may also include other hardware circuit configurations, and is not limited in this disclosure, so long as the functionality referred to in this disclosure is satisfied without departing from the spirit of the present disclosure.

In some embodiments, the acoustic device 100 may also include a communication port 108. The communication port 108 is used for data communication between the acoustic device 100 and the outside world, for example, the communication port 108 may be used for data communication between the acoustic device 100 and other devices.

In some embodiments, the acoustic device 100 may also include an internal communication bus 109. Internal communication bus 109 may connect the different system components. For example, the speaker 102, the first sound sensor module 103, the second sound sensor module 104, the processor 107, the storage medium 106, and the communication port 108 may all be connected by an internal communication bus 109.

The storage medium 106 may include a data storage device. The data storage device may be a non-transitory storage medium or a transitory storage medium. For example, the data storage devices may include one or more of a magnetic disk 1061, a read-only storage medium (ROM) 1062, or a random access storage medium (RAM) 1063. The storage medium 106 also includes at least one set of instructions stored in the data storage device. The instruction set includes instructions, which are computer program code that can include programs, routines, objects, components, data structures, procedures, modules, etc. that perform the active noise reduction methods provided herein.

The at least one processor 107 is configured to execute the at least one instruction set described above. When the acoustic device 100 is operating, the at least one processor 107 reads the at least one instruction set and performs the active noise reduction method provided herein according to the instructions of the at least one instruction set. The processor 107 may perform all or part of the steps involved in the communication method. The processor 107 may be in the form of one or more processors, in some embodiments the processor 107 may include one or more hardware processors, such as microcontrollers, microprocessors, reduced Instruction Set Computers (RISC), application Specific Integrated Circuits (ASICs), application specific instruction set processors (ASIPs), central Processing Units (CPUs), graphics Processing Units (GPUs), physical Processing Units (PPUs), microcontroller units, digital Signal Processors (DSPs), field Programmable Gate Arrays (FPGAs), advanced RISC Machines (ARM), programmable Logic Devices (PLDs), any circuit or processor capable of executing one or more functions, or the like, or any combination thereof. For illustrative purposes only, the acoustic device 100 shown in FIG. 2 illustrates a case that includes only one processor 107. However, it should be noted that the acoustic device 100 in this specification may also include multiple processors, and thus, the operations and/or method steps disclosed in this specification may be performed by one processor as described in this specification, or may be performed jointly by multiple processors. For example, if the processor 107 of the acoustic device 100 performs steps a and B in this specification, it should be understood that steps a and B may also be performed by two different processors 120 in combination or separately (e.g., a first processor performs step a, a second processor performs step B, or the first and second processors together perform steps a and B).

As will be appreciated by those of ordinary skill in the art, FIG. 2 is but one design of noise reduction circuit 105. The noise reduction circuit 105 may also be designed in other hardware forms without departing from the spirit of the application disclosed in the present application. The specific design of the noise reduction circuit 105 is not limited in the present application.

As previously indicated, in the open acoustic device, the first sound signal collected and generated by the first sound sensor module 103 is not a pure ambient noise signal, but a mixed sound signal including an ambient noise signal and a leakage signal. Therefore, if the noise reduction circuit 105 performs feedforward noise reduction directly based on the first sound signal, the leakage signal may affect the feedforward noise reduction process, so that the feedforward noise reduction effect is poor.

In some embodiments, to reduce the impact of the leakage signal on the feedforward noise reduction effect, the acoustic device 100 may employ a physical isolation manner to position the first acoustic sensor module 103 at the acoustic zero position of the speaker 102. For example, the speaker 102 may be designed as a dipole loudspeaker, and the first acoustic sensor module 103 is located at an acoustic zero point of the dipole loudspeaker. Thus, the first acoustic sensor module 103 cannot collect leakage signals from the speaker 102, or only collects few leakage signals.

Fig. 3 shows a schematic diagram of leakage signals acquired by sound sensors at different locations in an acoustic device. Where FF1 and FF2 represent sound sensors located at the acoustic zero point position of the speaker 102, and FF3 represents a sound sensor located near the speaker 102. In the test process, after the speaker 102 is excited with a signal, a leakage signal acquired by FF1 is acquired to obtain a curve 301 as shown in fig. 3, a leakage signal acquired by FF2 is acquired to obtain a curve 302 as shown in fig. 3, and a leakage signal acquired by FF3 is acquired to obtain a curve 303 as shown in fig. 3. As can be seen from fig. 3, when the environmental frequency is low (for example, lower than 1500 Hz), the leakage signals collected by FF1 and FF2 are reduced by more than 20dB relative to the leakage signal collected by FF3, so that a certain noise reduction effect can be achieved.

In some embodiments, the distance between the first acoustic sensor module 103 and the acoustic zero position of the speaker 102 may be within a non-zero preset range. That is, the first sound sensor module 103 may be disposed at a position closer to the acoustic zero point position of the speaker 102, instead of being strictly located at the acoustic zero point position of the speaker 102. In this way, the requirements on the structural design and assembly process of the acoustic device 100 can be reduced.

The present application provides an active noise reduction method P100 capable of reducing the influence of a leakage signal on feedforward noise reduction by reducing the component of the leakage signal in a first sound signal, thereby improving the noise reduction effect. The above-described active noise reduction method P100 may be applied to a scenario in which the first sound sensor module 103 is not disposed at the acoustic zero position of the speaker 102, or may be applied to a scenario in which the first sound sensor module 103 is disposed at the acoustic zero position of the speaker 102. In the scenario that the first sound sensor module 103 is disposed at the acoustic zero position of the speaker 102, since there is still a problem that the speaker signal leaks to the first sound sensor module in a part of the frequency band (for example, when the frequency is higher than 5000Hz in fig. 3, the leakage signals collected by FF1 and FF2 are basically equivalent to the leakage signal collected by FF 3), the active noise reduction method P100 provided by the present application may be adopted to perform active noise reduction for the specific frequency band where the leakage exists, so as to improve the noise reduction effect. The active noise reduction method P100 may be independently applied to the acoustic device 100 provided in the present application, or may be combined with other active noise reduction methods described in other parts herein.

Fig. 4 shows a flow chart of an active noise reduction method provided in accordance with an embodiment of the present description. The active noise reduction method P100 may be performed by a noise reduction circuit 105 in the acoustic device 100. For example, when the noise reduction circuit 105 adopts the structure shown in fig. 2, the processor 107 in the noise reduction circuit 105 may read an instruction set stored in its local storage medium and then execute the active noise reduction method P100 described in the present specification according to an instruction of the instruction set. As shown in fig. 4, the active noise reduction method P100 may include:

s11: a first sound signal is obtained from a first sound sensor module, the first sound signal comprising an ambient noise signal from ambient noise and a leakage signal from a speaker.

As described above, the first sound sensor module 103 collects the first sound and converts the first sound into the first sound signal. The first sound is actually a sound obtained by mixing the environmental noise from the noise source 300 and the leakage sound from the speaker 102, and therefore, the first sound signal includes both the environmental noise signal corresponding to the environmental noise and the leakage signal corresponding to the leakage sound. The noise reduction circuit 105 is connected to the first sound sensor module 103, and can acquire a first sound signal from the first sound sensor module 103.

S12: a quasi-ambient noise signal is generated by clipping the component of the leakage signal in the first sound signal.

Specifically, the noise reduction circuit 105 may measure the component of the leak signal included in the first sound signal in some way, and further, subtract the component of the leak signal from the first sound signal to obtain the quasi-ambient noise signal. It should be noted that, since the component of the leak signal obtained by the measurement may deviate from the actual leak signal, the component of the leak signal obtained by the measurement is subtracted from the first sound signal, and the result obtained is not exactly equal to the actual ambient noise signal but approximately equal to the actual ambient noise signal. Therefore, the result of the clipping is referred to as a quasi-ambient noise signal in the present application. The quasi-ambient noise signal may be understood as a compensation signal resulting from a leakage compensation of the first sound signal.

Fig. 5 shows a schematic diagram of the active noise reduction principle of an acoustic device according to an embodiment of the present disclosure. As shown in fig. 5, assume that:

the transfer function between the sound emitted by the noise source 300 and the audio signal measured by the first sound sensor module 103 is denoted as h1;

The transfer function between the sound emitted by the noise source 300 and the audio signal measured by the second sound sensor module 104 is denoted as h2;

The transfer function between the sound emitted by the speaker 102 and the audio signal measured by the first sound sensor module 103 is denoted as h3;

The transfer function between the sound emitted by the speaker 102 and the audio signal measured by the second sound sensor module 104 is denoted as h4;

the transfer function between the input and output of the feedforward filter is noted as h5;

The transfer function between the input and output of the feedback filter is noted as h6;

the acoustic transfer function between the sound emitted by the speaker 102 and transmitted to the eardrum 202 is denoted as h7; and

The acoustic transfer function between the sound emitted by noise source 300 and transmitted to eardrum 202 is denoted as h8.

The environmental noise emitted by noise source 300 is denoted as S0; the first sound signal collected by the first sound sensor module 103 is denoted as S1; the second sound signal collected by the second sound sensor module 104 is marked as S2; the noise cancellation signal from speaker 102 is denoted S3; and the ambient noise at the eardrum 202 is noted as S4. In the present application, S4 refers to the environmental noise actually heard by the human ear, that is, the environmental noise remaining at the eardrum 202 after the noise reduction process.

By the acoustic transfer process shown in fig. 5, the following relationship exists among the above S0, S1, S2, S3, and S4:

s4=s3+s0+h8 equation (0)

S3=s1×h5 equation (1-1)

S3=s2×h6 formula (1-2)

S3=s1+s2+h6 equation (1-3)

S1=s0+s3+h3 formula (2)

S2=s3+s0+h2 equation (3)

Wherein, the formula (1-1) corresponds to a feedforward noise reduction mode, the formula (1-2) corresponds to a feedback noise reduction mode, and the formula (1-3) corresponds to a hybrid noise reduction mode.

The design principle of the feedforward filter h5 is analyzed by taking the feedforward noise reduction mode as an example.

In the feedforward noise reduction mode, substitution of the above formula (2) into the formula (1-1) can be obtained:

substituting formula (4) into formula (0) to obtain:

In an ideal case (in a case where the sound emitted from the speaker 102 does not leak to the first sound sensor module 103), h3=0, and the substitution into formula (5) yields:

S4=s0 (h8+h1 h5 h 7) formula (6)

The noise reduction objective of the active noise reduction technique is typically to minimize S4. Based on equation (6), it can be seen that in the ideal case h5 needs to be compensated for h1, h7 and h 8. In this case, the first acoustic sensor module may be referred to as an ideal feedforward acoustic sensor module, and the feedforward filter may be referred to as an ideal feedforward filter.

In a non-ideal case, especially when the first acoustic sensor module 103 in the open acoustic device is not located at the acoustic zero point of the speaker 102, h3+.0, therefore, the noise reduction circuit 105 may measure the transfer function h3 ^′ between the speaker 102 and the first acoustic sensor module 103 by means of in-mold control, where h3 ^′ +.h3. In the present application, considering that the transfer function h3 ^′ is measured and there may be a certain error with the actual transfer function h3, the transfer function h3 ^′ may also be referred to as an actual transfer function. The noise reduction circuit 105 may compensate the first sound signal with h3 ^′ during the feedforward noise reduction process to obtain a quasi-ambient noise signal. Further, the noise reduction circuit 105 may filter the environmental noise signal through an ideal feedforward filter to obtain a first noise cancellation signal.

In some embodiments, h3 ^′ may be measured as follows: the noise reduction circuit 105 sends a test audio signal to the speaker 102 to cause the speaker 102 to emit a corresponding test audio, which is collected by the first sound sensor module 103. The noise reduction circuit 105 acquires the acquired audio signal acquired by the first sound sensor module 103, and determines a transfer function h3 ^′ according to the test audio signal and the acquired audio signal. For example, assuming that the test audio signal is Y1 and the acquisition audio signal is Y2, h ^′ =y2/Y1. It can be seen that the noise reduction circuit 105 can measure h3 ^′ by controlling the speaker 102 to transmit the test audio signal. The implementation of this measurement h3 ^′ is simple and does not affect the noise reduction performance of the noise reduction circuit 105.

In some embodiments, given that h3 is generally related to the wearing pose of the acoustic device 100, the corresponding h3 may be different when the same acoustic device 100 is worn by different users, and the corresponding h3 may also be different when the same acoustic device is worn multiple times by the same user. Therefore, the noise reduction circuit 105 may perform the above measurement process when it detects that the acoustic device 100 is turned on or when it detects that the acoustic device 100 is worn by a user, thereby improving the accuracy of h3 ^′.

In some embodiments, the noise reduction circuit 105, after measuring h3 ^′, may generate the quasi-ambient noise signal as follows: the noise reduction circuit 105 obtains an input signal (S3) corresponding to the speaker 102, and provides a first gain to the input signal (S3) to obtain a first gain signal, where the first gain is h3 ^′. Thus, the first gain signal is S3 x h3 ^′. Furthermore, the noise reduction circuit 105 obtains a first sound signal (i.e. s1=s0+s1+s3×h3) from the first sound sensor module 103, and subtracts the first gain signal from the first sound signal to obtain the quasi-ambient noise signal. Wherein, the quasi-ambient noise signal can be expressed as: s1 ^′＝S0*h1+S3*h3-S3*h3^′.

S13: a first noise cancellation signal is generated based on the quasi-ambient noise signal.

In some embodiments, with continued reference to fig. 5, the noise reduction circuit 105 may input the quasi-ambient noise signal S1 ^′ to a feedforward filter (h 5), and filter the ambient noise signal (S1 ^′) through the feedforward filter to obtain a first noise cancellation signal. Wherein the feedforward filter is configured to adjust at least one of a gain or a phase of the ambient noise signal (S1 ^′) such that the resulting first noise cancellation signal is capable of being offset with at least a portion of the ambient noise in the partial space at and/or around the eardrum 202. It should be appreciated that the feedforward filter described above may be an ideal feedforward filter, i.e., the ideal amplitude-phase response of the feedforward filter described above may be designed based on equation (6).

S14: the first noise cancellation signal is sent to a speaker to cause the speaker to convert the first noise cancellation signal to first noise cancellation audio to reduce the volume of the ambient noise at the eardrum.

As previously described, the noise reduction circuit 105 is communicatively coupled to the speaker 102. The noise reduction circuit 105 may transmit the first noise cancellation signal to the speaker 102 after generating the first noise cancellation signal. In this way, the speaker 102 plays the first noise cancellation audio corresponding to the first noise cancellation signal, so that the first noise cancellation audio and the environmental noise at the eardrum 202 cancel or partially cancel, thereby achieving the purpose of noise reduction.

Fig. 6 shows a schematic diagram of a noise reduction effect of an active noise reduction method according to an embodiment of the present disclosure. As shown in fig. 6, curves 601 and 602 correspond to the noise reduction results of two test scenarios, respectively. The test procedure corresponding to curve 601 is as follows: the noise reduction circuit 105 acquires a first sound signal acquired by FF1 (located at the acoustic zero point position of the speaker 102) in fig. 3, which does not contain or substantially does not contain a leak signal from the speaker 102. The noise reduction circuit 105 performs feedforward noise reduction based on the first sound signal using an ideal feedforward filter, resulting in a noise reduction result shown by a curve 601. The test procedure corresponding to curve 602 is as follows: the noise reduction circuit 105 acquires a first sound signal acquired by FF3 (not located at the acoustic zero point position of the speaker 102 or located outside the acoustic zero point of the speaker 102) in fig. 3, and the first sound signal contains a leak signal from the speaker 102. The noise reduction circuit 105 adopts the active noise reduction method shown in fig. 4, firstly cuts down the component of the leakage signal in the first sound signal to obtain the quasi-environment noise signal, and then adopts an ideal feedforward filter to perform feedforward noise reduction based on the quasi-environment noise signal. As can be seen from fig. 6, the two noise reduction results are substantially identical for curve 601 and curve 602. From this, the noise reduction circuit 105 can effectively improve the noise reduction effect of the open acoustic device by first reducing the component of the leakage signal in the first sound signal to obtain the quasi-ambient noise signal and then generating the first noise cancellation signal based on the quasi-ambient noise signal.

In the active noise reduction method P100 shown in fig. 4, after the first sound signal is obtained from the first sound sensor module, the noise reduction circuit 105 first cuts the component of the leakage signal from the first sound signal to generate the quasi-ambient noise signal, and then performs feedforward noise reduction based on the quasi-ambient noise signal to generate the first noise cancellation signal. In some embodiments, the noise reduction circuit 105 may interchange the step of clipping and the step of feedforward noise reduction described above. Specifically, after the first sound signal is obtained from the first sound sensor module (S1), the noise reduction circuit 105 performs feedforward noise reduction (h 5) on the first sound signal to generate an intermediate noise cancellation signal (S1×h5). Because the first sound signal includes the environmental noise signal and the leakage signal, when the noise reduction circuit 105 performs feedforward noise reduction on the first sound signal, feedforward noise reduction is performed on the environmental noise signal and the leakage signal at the same time, and thus the obtained intermediate noise cancellation signal (S1 x h 5) includes both the feedforward noise reduction result of the environmental noise signal and the feedforward noise reduction result of the leakage signal. The feedforward noise reduction result of the leakage signal can be estimated by the following method: the input signal (S3) corresponding to the speaker is obtained, and the first gain (h 3 ') is provided to the input signal to obtain the first gain signal (S3×h3 '), it should be understood that the first gain signal S3×h3' may be regarded as an estimated value of the leakage signal. The first gain signal (S3 h3 ') is filtered based on the feedforward noise reduction parameter (h 5) to obtain a filtering result (S3 h 3'/h 5) of the leakage signal. Further, the noise reduction circuit 105 subtracts the feedforward noise reduction result (S3×h3'×h5) of the leakage signal from the intermediate noise reduction signal (S1×h5) to obtain a first noise reduction signal (S1×h5-S3×h3' ×h5). It should be noted that, in the above manner, h3' is a transfer function between the speaker and the first sound sensor module, and a measurement manner thereof may be referred to the description of the related content, which is not repeated herein.

In summary, in the active noise reduction method P100 provided in the present disclosure, when the first sound signal includes both the ambient noise signal and the leakage signal, the noise reduction circuit 105 may generate the quasi-ambient noise signal by reducing the component of the leakage signal in the first sound signal, generate the first noise cancellation signal based on the quasi-ambient noise signal, and further convert the first noise cancellation signal into the first noise cancellation audio through the speaker, so as to achieve the noise reduction purpose. Because the noise reduction circuit 105 reduces the component of the leakage signal in the first sound signal in the feedforward noise reduction process, the influence of the leakage signal on feedforward noise reduction is reduced, and thus the noise reduction effect of active noise reduction can be improved.

In general, the noise reduction circuit 105 should design/adjust the noise reduction parameters of the noise reduction circuit 105 with "minimize the ambient noise at the eardrum 202 (S4)" as a noise reduction target. In a closed acoustic device, the second acoustic signal (S2) acquired by the second acoustic sensor module 104 is equal or approximately equal to the ambient noise (S4) at the eardrum 202. Therefore, "minimizing the second sound signal (S2)" can be regarded as a noise reduction target in the closed acoustic device. However, in the open acoustic device, since an open space is formed between the speaker 102 and the eardrum 202, the second acoustic signal (S2) measured by the second acoustic sensor module 104 is no longer in equal or approximately equal relation to the ambient noise (S4) at the eardrum 202.

During the course of the study of the present application, it was found that the reason that S2 and S4 are no longer equal or approximately equal is as follows: in connection with the acoustic delivery process shown in fig. 5, the second sound signal (S2) measured by the second sound sensor module 104 may be expressed as formula (3), and the ambient noise (S4) at the eardrum 202 may be expressed as formula (0), as follows:

s2=s3+s0+h2 equation (3)

S4=s3+s0+h8 equation (0)

As can be seen from the above formula (3) and formula (0), S2 and S4 can be regarded as mixed signals of two sound signals, wherein the first sound signal is from the noise cancellation signal (S3) emitted from the speaker 102 and the second sound signal is from the ambient noise signal (S0) emitted from the noise source 300. Regarding the second sound signal, considering that in the frequency band to be denoised in general, the transfer function (h 2) between the sound emitted by the noise source 300 and the audio signal measured by the second sound sensing module 104 is equal or approximately equal to the transfer function (h 8) between the sound emitted by the noise source 300 and the eardrum 202, that is, h2≡h8, so that the components of the second sound signal in S2 and S4 are equivalent, and the difference between S2 and S4 mainly comes from: the difference between the component of the noise canceling signal in S2 (S3 h 4) and the component of the noise canceling signal in S4 (S3 h 7).

In the closed acoustic device, the transfer function (h 4) between the sound emitted from the speaker 102 and the audio signal measured by the second sound sensor module 104 is equal or approximately equal to the transfer function (h 7) between the sound emitted from the speaker 102 and the eardrum 202, that is, h4≡h7, and thus S2 obtained based on the formula (3) and S4 obtained based on the formula (0) are also equal or approximately equal. In the open acoustic device, the transfer function (h 4) between the sound emitted from the speaker 102 and the audio signal measured by the second sound sensor module 104 is no longer equal or approximately equal to the transfer function (h 7) between the sound emitted from the speaker 102 and the eardrum 202, and therefore, S2 obtained based on the formula (3) and S4 obtained based on the formula (0) are no longer equal or approximately equal.

It can be appreciated that since in the open acoustic device S2 and S4 are no longer in equal or approximately equal relationship, the noise reduction effect would be poor if "minimizing S2" were still the noise reduction target.

In order to solve the above technical problems, the inventors of the present application have proposed the following technical ideas in the course of research: by specifically designing the structure of the acoustic apparatus 100 and the positions of the respective devices, it is possible to: although S4 and S2 are not equal, S4 may be estimated based on S2 (or S4 and S2 have the same trend of change). In this way, S4 may be estimated based on S2, and active noise reduction may be performed with minimized S4 as a noise reduction target, or noise reduction parameters required for "minimizing S4 as a noise reduction target" may be derived based on noise reduction parameters required for "minimizing S2 as a noise reduction target", so as to improve active noise reduction effects.

Based on the foregoing analysis, the difference between S4 and S2 is mainly due to: the difference between the component of the noise canceling signal in S2 (S3 h 4) and the component of the noise canceling signal in S4 (S3 h 7). If S4 based on S2 estimation is to be implemented, the usual consideration is that h4 and h7 need to be known separately. However, during the course of the inventors' studies, h7 and h4 were both found to be amounts strongly correlated with the pose of the acoustic device 100, i.e., h4 was different from each other and h7 was also different from each other in the case where different users worn the acoustic device, even in the case where the same user worn the acoustic device multiple times, h4 was also different from each other and h7 was also different from each other. In addition, in an actual application scene, an acoustic sensor does not exist at the eardrum 202 of the user, so that the measurement difficulty of h7 is high, and the estimation of S4 is difficult. Through further studies by the inventors, it was found that although both h4 and h7 are strongly correlated to the pose of the acoustic device 100, the positions of the second sound sensor module 104 and the speaker 102 can be designed such that: h4 and h7 satisfy a first preset relationship, and the first preset relationship is independent of the pose of the acoustic device 100. Wherein the first preset relationship is independent of the pose of the acoustic device 100, that is, the first preset relationship is satisfied between h4 and h7 no matter in which pose the acoustic device 100 is worn by the user. For example, the first preset relationship is satisfied between h4 and h7 when the acoustic device 100 is worn by different users. For another example, the first preset relationship is satisfied between h4 and h7 when the acoustic device 100 is worn multiple times by the same user.

The present application is not limited to the specific form of the first preset relationship. In the design stage of the acoustic device 100, the first preset relationship between h4 and h7 may be obtained by testing a process of wearing the acoustic device multiple times by a large number of users. In some embodiments, the first preset relationship may be: h7/h4=h9. The value of h9 is not limited in the present application. It should be appreciated that in case a first predetermined relationship is satisfied between h4 and h7, the following relationship may be satisfied between S2 and S4: the relation between the component of the noise canceling signal in S4 (S3 h 7) and the component of the noise canceling signal in S2 (S3 h 4) is as follows: (S3 x h 7)/(S3 x h 4) =h9; or the intensity of the component (S3×h4) of the noise cancellation signal in S2 is lower by xdB than the intensity of the component (S3×h7) of the noise cancellation signal in S4, where x may be 1, 2 or any other value.

It should be noted that, the specific positions of the second sound sensor module 104 and the speaker 102 are not limited in the present application, as long as the positions of the two can make h4 and h7 satisfy the first preset relationship, and the first preset relationship is independent of the pose of the acoustic device 100. In some embodiments, the speaker 102 may be positioned near the ear canal opening with the sound emitting surface (i.e., the surface on which the sound emitting end is located) facing the ear canal opening. For example, because of the shape and mass distribution of the acoustic device 100, a certain position of the acoustic device 100 is close to the ear canal orifice, regardless of the pose in which the acoustic device 100 is worn, the speaker 102 may be disposed at that position. The second sound sensor module 104 may be disposed on the sound output face of the speaker 102. In addition, when designing the specific position of the second sound sensor module 104 on the sound output surface, the following principle can be considered: (1) The sound pickup end of the second sound sensor module 104 is far away from the skin of the user, (2) the sound pickup end of the second sound sensor module 104 is as close to the meatus of the ear as possible. It should be appreciated that the positions of the speaker 102 and the second sound sensor module 104 determined in the above manner can make h4 and h7 not susceptible to the wearing pose, i.e. h4 and h7 satisfy the same first preset relationship no matter in which pose the acoustic device 100 is worn. In addition, the positions of the speaker 102 and the second sound sensor module 104 determined in the above manner can also enable the second sound signal S2 collected by the second sound sensor module 104 to be closer to the environmental noise S4 at the eardrum 202, and the second sound signal S2 is not susceptible to the influence of skin reflection, so that the S4 estimated based on the first preset relationship and the second sound signal S2 is more accurate.

In the case that the first preset relation is satisfied between h4 and h7 and is independent of the pose of the acoustic device 100, the active noise reduction method P200 is provided, and the noise reduction parameters can be adjusted based on the second acoustic signal (S2) and the first preset relation no matter the pose of the acoustic device 100 is worn by the user, so that the active noise reduction effect is improved. The active noise reduction method P200 may be independently applied to the acoustic device 100 provided in the present application, or may be combined with other active noise reduction methods described in other sections herein.

Fig. 7 shows a flowchart of another active noise reduction method P200 provided according to an embodiment of the present description. The active noise reduction method P200 may be performed by the noise reduction circuit 105 in the acoustic device 100. For example, the processor 107 in the noise reduction circuit 105 may read the instruction set stored in its local storage medium and then execute the active noise reduction method P200 described in this specification according to the instruction of the instruction set. As shown in fig. 7, the active noise reduction method P200 may include:

S21: a second sound signal is acquired from a second sound sensor module.

S22: and adjusting noise reduction parameters of the noise reduction circuit based on the second sound signal and the first preset relation.

In some embodiments, the noise reduction circuit 105 may determine the ambient noise at the eardrum 202 based on the second sound signal (S2) and the first preset relationship (S4). Further, the noise reduction circuit 105 adjusts the noise reduction parameter with the objective of minimizing the environmental noise at the eardrum 202 (S4).

In some embodiments, the noise reduction circuit 105 may estimate S4 as follows:

(1) A first transfer function h4' between the sound emitted by the speaker 102 and the audio signal measured by the second sound sensor module 104 is measured.

In some embodiments, h4' may be measured in the following manner: the noise reduction circuit 105 sends a test audio signal to the speaker 102 to cause the speaker 102 to emit corresponding test audio that is collected by the second sound sensor module 104. The noise reduction circuit 105 acquires the collected audio signal collected by the second sound sensor module 104, and determines a first transfer function h4' according to the test audio signal and the collected audio signal. For example, assuming that the test audio signal is Y1 and the acquisition audio signal is Y2, h4' =y2/Y1. It can be seen that the noise reduction circuit 105 can measure h4' by controlling the speaker 102 to transmit the test audio signal. The implementation of this measurement h4' is simple and does not affect the noise reduction performance of the noise reduction circuit 105. In some embodiments, given that h4 is generally associated with the wearing pose of the acoustic device 100, the corresponding h4 may be different when the same acoustic device 100 is worn by different users, and the corresponding h4 may also be different when the same acoustic device is worn multiple times by the same user. Therefore, the noise reduction circuit 105 may perform the above measurement process when it is detected that the acoustic device 100 is turned on or when it is detected that the acoustic device 100 is worn by a user, thereby improving the accuracy of h4'.

(2) Determining ambient noise at the eardrum based on the first transfer function, the first preset relationship, and the second sound signal.

Specifically, the second transfer function h7 'between the sound emitted by the speaker 102 and the eardrum 202 may be determined based on the first transfer function h4' and the first preset relationship.

For example, assume that the first preset relationship is: h7/h4=h9, a second transfer function h7' =h4 ' ×h9 can be obtained based on the first transfer function h4' and the first preset relationship.

Further, S4 may be determined based on the first transfer function h4', the second transfer function h7', and S2, specifically as follows:

based on equation (3), first, we can get:

S0.h2=s2-s3.h4 equation (12)

Based on the previous analysis, the component of the ambient noise in S2 (S0 h 2) is approximately equal to the component of the ambient noise in S4 (S0 h 8), i.e.:

S0.h8.apprxeq.s0.h2=s2-s3.h4 equation (13)

Substituting equation (13) into equation (0) yields:

s4≡s3×h7+ (S2-S3×h4) equation (14)

In equation (14), S3 is an input signal of the speaker 102, h4 may be replaced by a first transfer function h4', h7 may be replaced by a second transfer function h7', and S2 is a second sound signal collected by the second sound sensor module 104. From this, it can be seen that the noise reduction circuit 105 can estimate S4 based on the first transfer function h4', the second transfer function h7', the second sound signal S2, and the input signal S3 of the speaker 102.

The active noise reduction process determines the environmental noise (S4) at the eardrum 202 based on the second sound signal (S2) and the first preset relationship, and then uses the minimized environmental noise (S4) at the eardrum 202 as a noise reduction target, thereby improving the accuracy of the noise reduction target and improving the active noise reduction effect.

The above embodiment is based on the following assumption in determining S4: the transfer function (h 2) between the sound emitted by the noise source 300 and the audio signal measured by the second sound sensing module 104 is approximately equal to the transfer function (h 8) between the sound emitted by the noise source 300 and the eardrum 202, i.e. h2≡h8. The inventor considers that in practical application scenarios, h2 and h8 are not usually in a strictly equal relationship, which leads to a certain error in S4 determined in the above embodiment. Therefore, in order to further improve the accuracy of S4, h2 and h8 may also be considered in determining S4. However, h2 and h8 are also amounts related to the pose of the acoustic device 100, h2 is different from each other in the case where different users wear the acoustic device, h8 is different from each other, and even in the case where the same user wears the acoustic device a plurality of times, h2 is different from each other, and h8 is also different from each other. Therefore, it is difficult to measure h2 and h8 separately. As a result of further studies by the inventors, it was found that when the positions of the second sound sensor module 104 and the speaker 102 are designed, in addition to the first preset relationship being satisfied between h4 and h7, a second preset relationship between h2 and h8 may be satisfied, and the second preset relationship is also independent of the pose of the acoustic device 100. Wherein the second preset relationship is independent of the pose of the acoustic device 100, that is, the second preset relationship is satisfied between h2 and h8 no matter in which pose the acoustic device 100 is worn by the user. For example, the second preset relationship is satisfied between h2 and h8 when the acoustic device 100 is worn by a different user. For another example, the second preset relationship is satisfied between h2 and h8 when the acoustic device 100 is worn multiple times by the same user.

The present application is not limited to the specific form of the second preset relationship. In the design stage of the acoustic device 100, the relationship between h2/h1 and h8/h1 can be obtained by testing the process of wearing the acoustic device multiple times by a large number of users, and a second preset relationship between h2 and h8 can be obtained based on the relationship. In some embodiments, the second preset relationship may be: h8/h2=h10. The value of h10 is not limited in the present application. It should be appreciated that in case a second predetermined relationship is satisfied between h2 and h8, the following relationship may be satisfied between S2 and S4: the component (S0 h 8) of the ambient noise signal in S4 and the component (S0 h 2) of the ambient noise signal in S2 have the following relationship: (S0 x h 8)/(S0 x h 2) =h10; or the intensity of the component (S0 h 2) of the ambient noise signal in S2 is lower ydB than the intensity of the component (S0 h 8) of the ambient noise signal in S4, where y may be 1, 2 or any other value.

In some embodiments, in a case where a first preset relationship is satisfied between h4 and h7, a second preset relationship is satisfied between h2 and h8, and both the first preset relationship and the second preset relationship are independent of the pose of the acoustic device 100, S4 may be estimated based on the first preset relationship, the second preset relationship, and S2. The specific mode is as follows:

(1) A first transfer function h4 ^′ between the sound emitted by the speaker 102 and the audio signal measured by the second sound sensor module 104 is measured. The measurement process of the first transfer function h4 ^′ may be referred to in the description of the related content, which is not described herein.

(2) Determining ambient noise at the eardrum based on the first transfer function, the first preset relationship, the second preset relationship, and the second sound signal.

Specifically, the second transfer function h7 ^′ between the sound emitted from the speaker 102 and the eardrum 202 may be determined based on the first transfer function h4 ^′ and the first preset relationship. The determination of the second transfer function h7 ^′ may be referred to in the description of the related content, which is not described herein.

Further, S4 may be determined based on the second preset relationship, the first transfer function h4 ^′, the second transfer function h7 ^′, and S2, which is specifically as follows:

based on equation (3), first, we can get:

S0.h2=s2-s3.h4 equation (12)

Based on the second preset relationship, it is possible to obtain:

S0=s0×h2×h10= (S2-S3×h4) ×h10 equation (15)

Substituting equation (15) into equation (0) yields:

s4=s3+h7+ (S2-S3 h 4) h10 equation (16)

In formula (16), S3 is an input signal of the speaker 102, h4 may be replaced by a first transfer function h4 ^′, h7 may be replaced by a second transfer function h7 ^′, S2 is a second sound signal collected by the second sound sensor module 104, and h10 may be obtained based on a second preset relationship. It follows that S4 can be determined based on the first transfer function h4 ^′, the second transfer function h7 ^′, the second preset relationship, the second sound signal S2, and the input signal S3 of the speaker 102.

After S4 is estimated, the noise reduction parameters of the noise reduction circuit 105 may be adjusted with the minimized S4 as a noise reduction target. In some embodiments, the noise reduction circuit 105 may include a feedforward filter, in which case the noise reduction parameters described above may include filter parameters of the feedforward filter. In some embodiments, the noise reduction circuit 105 may include a feedback filter, in which case the noise reduction parameters described above may include filter parameters of the feedback filter. In some embodiments, the noise reduction circuit 105 may include a feedforward filter and a feedback filter, in which case the noise reduction parameters described above may include at least one of a filtering parameter of the feedforward filter or a filtering parameter of the feedback filter.

In some embodiments, the filtering parameters of the feedforward filter or the feedback filter may include: at least one of a filter gain, a filter phase, or a quality factor. The quality factor can be expressed by the ratio of the center frequency F (in Hz) of the filter to the-3 dB bandwidth B (in Hz), i.e., the quality factor q=f/B, describing the ability of the filter to separate adjacent frequency components in the signal. The higher the quality factor, the higher the resolution of the filter for adjacent frequency components.

In some embodiments, the noise reduction parameters of the noise reduction circuit 105 may include a filter gain of a feedforward filter. In this case, for convenience of description, the filter gain of the feedforward filter required to "minimize the second sound signal (S2) as a noise reduction target" is referred to as a first filter gain, and the filter gain of the feedforward filter required to "minimize the ambient noise (S4) at the eardrum 202 as a noise reduction target" is referred to as a second filter gain. Then, when the first preset relationship between h4 and h7 is satisfied, there is a certain relationship between the signal strengths of S2 and S4, for example, the signal strength of S2 is lower by xdB than the signal strength of S4. In this case, the relationship between the first filter gain and the second filter gain is satisfied as well.

By way of example, fig. 8A shows a schematic diagram of a frequency response curve for feedforward noise reduction of ambient noise at the eardrum with different feedforward filter gains with the acoustic device worn by the first user. Fig. 8B shows a schematic diagram of a frequency response curve for feedforward noise reduction of a second sound signal with different feedforward filter gains with an acoustic device worn by a first user. Wherein, assuming that the first preset relationship is satisfied between h4 and h7, the second sound signal (S2) is 2dB lower than the intensity of the ambient noise (S4) at the eardrum 202.

Referring to fig. 8A and 8B, when the acoustic device 100 is worn by the first user, the feedforward filters in the noise reduction circuit 105 actively reduce noise with different filter gains (increasing from 0dB to 4dB in sequence), respectively. The frequency response curve obtained by feedforward noise reduction based on the ambient noise at the eardrum 202 (S4) is shown in fig. 8A at different filter gains. The frequency response curve obtained by feedforward noise reduction based on the second sound signal (S2) at different filter gains is shown in fig. 8B. As can be seen from fig. 8A, if the noise reduction target is to minimize the environmental noise at the eardrum 202 (S4), the second filter gain required for the feedforward filter is 4dB. As can be seen from fig. 8B, if the minimized second sound signal (S2) is used as the noise reduction target, the first filtering gain required for the feedforward filter is 2dB.

Fig. 9A shows a schematic diagram of a frequency response curve for feedforward noise reduction of ambient noise at the eardrum with different feedforward filter gains with the acoustic device worn by a second user. Fig. 9B shows a schematic diagram of a frequency response curve for feedforward noise reduction of a second sound signal with different feedforward filter gains with the acoustic device worn by user B. Wherein, assuming that the first preset relationship is satisfied between h4 and h7, the second sound signal (S2) is 2dB lower than the intensity of the ambient noise (S4) at the eardrum 202.

Referring to fig. 9A and 9B, when the acoustic device 100 is worn by a second user, the feedforward filters in the noise reduction circuit 105 actively reduce noise with different filter gains (increasing from 0dB to 4dB in sequence), respectively. The frequency response curve obtained by feedforward noise reduction based on the ambient noise at the eardrum 202 (S4) is shown in fig. 9A at different filter gains. The frequency response curve obtained by feedforward noise reduction based on the second sound signal (S2) at different filter gains is shown in fig. 9B. As can be seen from fig. 9A, if the noise reduction target is to minimize the environmental noise at the eardrum 202 (S4), the second filter gain required for the feedforward filter is 3dB. As can be seen from fig. 8B, if the minimized second sound signal (S2) is used as the noise reduction target, the first filtering gain required for the feedforward filter is 1dB.

As can be seen from fig. 8A to 9B, "the relationship between the first filter gain and the second filter gain" is the same as "the relationship between the intensity of the second sound signal (S2) and the intensity of the environmental noise (S4) emitted from the eardrum 202". That is, if the intensity of the second sound signal (S2) is lower by xdB than the intensity of the ambient noise (S4) at the eardrum 202, the first filter gain is lower by xdB than the second filter gain.

Thus, the noise reduction circuit 105 may also adjust the filter gain of the feedforward filter in the following manner: a first filter gain of the feedforward filter is determined with the minimized second sound signal (S2) as a noise reduction target. Then, the noise reduction circuit 105 determines the above-described second filter gain based on the first filter gain and the first preset relationship, and adjusts the current filter gain of the feedforward filter to the second filter gain. For example, assume that the first preset relationship is such that the intensity of the second sound signal (S2) is 2dB lower than the intensity of the ambient noise (S4) at the eardrum 202. The noise reduction circuit 105 first determines that the first filter gain is 2dB with the minimized second sound signal (S2) as a noise reduction target. Then, the noise reduction circuit 105 may increase by 2dB on the basis of the first filter gain, resulting in a second filter gain of 4dB. Thus, the current filtering gain of the feedforward filter is adjusted to 4dB.

In some embodiments, the acoustic device 100 may provide a plurality of modes of operation to the user, with each mode of operation having a default noise reduction parameter corresponding to the noise reduction circuit 105, and different modes of operation having different default noise reduction parameters corresponding to the different modes of operation. In some embodiments, an interactive control may be provided on the acoustic device 100, which may be operated by a user to switch different modes of operation. In some embodiments, the acoustic device 100 may provide an interactive interface that may be presented on a screen of the acoustic device 100 or on a target device communicatively connected to the acoustic device 100. The user may select different modes of operation through the interactive interface. In some embodiments, the plurality of operation modes respectively correspond to different environment types. The user may interactively indicate the type of environment currently in the acoustic device 100, and the noise reduction circuit 105 may switch to a corresponding operating mode based on the type of environment currently in. In some embodiments, the plurality of operation modes may respectively correspond to different user types. The user may indicate to the acoustic device 100 the user type to which the user belongs in an interactive manner, and the noise reduction circuit 105 may switch to a corresponding operation mode based on the user type to which the user belongs.

In this way, in S22, the noise reduction circuit 105 may obtain the target operation mode indicated by the user in the multiple operation modes, and further adjust the default noise reduction parameters corresponding to the target operation mode based on the second sound signal (S2) and the first preset relationship. It should be appreciated that the acoustic device 100 is capable of meeting noise reduction requirements for different users or different environments by providing multiple modes of operation.

S23: and actively reducing noise based on the adjusted noise reduction parameters.

In some embodiments, the noise reduction circuit 105 may also obtain a first sound signal from the first sound sensor module and filter at least one of the first sound signal or the second sound signal based on the adjusted noise reduction parameters to generate a noise cancellation signal. Further, the noise reduction circuit 105 sends the noise cancellation signal to a speaker to cause the speaker to convert the noise cancellation signal to noise cancellation audio to reduce the volume of ambient noise at the eardrum.

In some embodiments, when the acoustic device 100 is operating in the feed-forward noise reduction mode, the noise reduction circuit 105 may filter the first sound signal based on the adjusted noise reduction parameters to generate a noise cancellation signal. For example, the noise reduction circuit 105 may input the first sound signal into a feedforward filter, and filter the first sound signal through the feedforward filter to obtain the noise cancellation signal. In some embodiments, when the first sound signal includes both the ambient noise signal and the leakage signal, the noise reduction circuit 105 may first generate the quasi-ambient noise signal by reducing a component of the leakage signal in the first sound signal, and then filter the quasi-ambient noise signal based on the adjusted noise reduction parameter to obtain the noise cancellation signal. On the one hand, because the accuracy of the noise reduction target is ensured when the noise reduction parameters are adjusted, the active noise reduction is performed based on the adjusted noise reduction parameters, and the active noise reduction effect can be improved. On the other hand, by reducing the component of the leakage signal in the first sound signal, the influence of the leakage signal on the feedforward noise reduction process is reduced, and the active noise reduction effect can be further improved.

In some embodiments, when the acoustic device 100 is operating in the feedback noise reduction mode, the noise reduction circuit 105 may filter the second sound signal based on the adjusted noise reduction parameters to generate a noise cancellation signal. For example, the noise reduction circuit 105 may input the second sound signal into a feedback filter, and filter the second sound signal through the feedback filter to obtain the noise cancellation signal.

In some embodiments, when the acoustic device 100 is operating in the hybrid noise reduction mode, the noise reduction circuit 105 may filter the first sound signal based on the adjusted noise reduction parameters to obtain a first noise cancellation signal. For example, the noise reduction circuit 105 inputs the first sound signal to a feedforward filter, and filters the first sound signal by the feedforward filter to obtain a first noise cancellation signal. The noise reduction circuit 105 may also filter the second sound signal based on the adjusted noise reduction parameter to obtain a second noise cancellation signal. For example, the noise reduction circuit 105 inputs the second sound signal to a feedback filter, and filters the second sound signal through the feedback filter to obtain a second noise cancellation signal. Further, the noise reduction circuit 105 synthesizes the first noise reduction signal and the second noise reduction signal to obtain a noise reduction signal. In some embodiments, where the first sound signal includes both an ambient noise signal and a leakage signal, the noise reduction circuit 105 may first generate a quasi-ambient noise signal by reducing a component of the leakage signal in the first sound signal, and then filter the quasi-ambient noise signal based on the adjusted noise reduction parameters to obtain the first noise cancellation signal. On the one hand, because the accuracy of the noise reduction target is ensured when the noise reduction parameters are adjusted, the active noise reduction is performed based on the adjusted noise reduction parameters, and the active noise reduction effect can be improved. On the other hand, by reducing the component of the leakage signal in the first sound signal, the influence of the leakage signal on the feedforward noise reduction process is reduced, and the active noise reduction effect can be further improved.

In summary, in the active noise reduction method P200 provided in the present disclosure, since the acoustic transfer function (h 4) between the sound emitted by the speaker 102 and the audio signal measured by the second sound sensor module 104 and the acoustic transfer function (h 7) between the sound emitted by the speaker 102 and the eardrum 202 satisfy the first preset relationship, and the first preset relationship is independent of the pose of the acoustic device 100, the noise reduction circuit 105 may adjust the noise reduction parameter based on the second sound signal (S2) and the first preset relationship, and perform active noise reduction based on the adjusted noise reduction parameter. Because the noise reduction circuit 105 adjusts the noise reduction parameters based on the second sound signal (S2) and the first preset relationship, the adjusted noise reduction parameters conform to the most essential noise reduction target, so that the noise reduction effect of active noise reduction can be improved.

As previously described, in some embodiments, one sound sensor may be included in the first sound sensor module 103. In this case, since the environmental noise may be transmitted from an arbitrary direction, the following may occur: ambient noise will have reached the speaker 102 or eardrum 202 before reaching the sound sensor. For example, assuming that the sound sensor is disposed on a first side of the acoustic device 100 (e.g., the side facing the front of the user) and the noise source 300 is disposed on a second side of the acoustic device 100 (e.g., the side facing the back of the user), since the sound sensor is farther from the noise source 300, the ambient noise emitted by the noise source 300 reaches the speaker 102 or the eardrum 202 before it is captured by the sound sensor. In this way, the noise reduction circuit 105 performs causality of feedforward noise reduction, so that the noise reduction effect of feedforward noise reduction is poor, especially the feedforward noise reduction effect of certain frequency bands (for example, middle-high frequency bands) is poor, and even noise improvement heard by human ears may be caused.

To this end, in some embodiments, a plurality of sound sensors may be included in the first sound sensor module 103. For convenience of description, the number of sound sensors included in the first sound sensor module 103 is denoted as N, which is an integer greater than or equal to 2. The N sound sensors are physically connected to the support 101, respectively, and are distributed on the side remote from the eardrum with respect to the speaker 102. Regardless of speaker 102 leakage, each sound sensor is configured to collect ambient noise from noise source 300 and generate an ambient noise signal. For illustration, hereinafter, the environmental noise signal collected by each sound sensor is referred to as an individual environmental noise signal, and the environmental noise signal collected by the first sound sensor module 103 is referred to as an integrated environmental noise signal.

The N sound sensors are oriented differently relative to a target point on the speaker 102. In some embodiments, the target point may be a center point or an output point of the speaker 102. Because the N sound sensors have different directions with respect to the target point, when the ambient noise is transmitted from different directions, at least one sound sensor of the N sound sensors can collect the ambient noise before the speaker 102.

In some embodiments, n=2. Fig. 10 is a schematic diagram showing the distribution of each sound sensor in the case where 2 sound sensors are included in the first sound sensor module. As shown in fig. 10, when n=2, the first sound sensor module 103 may include: a sound sensor 1031 and a sound sensor 1032. The 2 sound sensors may be respectively located on two sides of the acoustic device 100 facing opposite directions, or the directions of the 2 sound sensors with respect to the target point are opposite. For example, when acoustic device 100 is worn on the head of a user, sound sensor 1031 is located on a first side of acoustic device 100 that faces the front of the user and sound sensor 1032 is located on a second side of acoustic device 100 that faces the rear of the user. Thus, when the ambient noise is emitted from a noise source in front of the user, the phase of the ambient noise reaching the sound sensor 1031 (or the phase of the individual ambient noise signal measured by the sound sensor 1031) leads the phase of the ambient noise reaching the sound output end of the speaker 102. When the ambient noise is emitted by a noise source behind the user, the phase of the ambient noise reaching the sound sensor 1032 (or the phase of the individual ambient noise signal measured by the sound sensor 1032) leads the phase of the ambient noise reaching the sound outlet end of the speaker 102. In some embodiments, the 2 sound sensors may be located at the acoustic zero position of the speaker 102. In this way, the signals collected by the 2 sound sensors do not contain leakage signals from the speaker 102, thereby improving the active noise reduction effect.

In some embodiments, n=3. Fig. 11 shows a schematic diagram of the distribution of each sound sensor in the case where 3 sound sensors are included in the first sound sensor module. As shown in fig. 11, when n=3, the first sound sensor module 103 may include: sound sensor 1031, sound sensor 1032, and sound sensor 1033. Wherein the 3 sound sensors may be distributed on three sides of the acoustic device 100 facing in different directions. For example, when acoustic device 100 is worn on the head of a user, sound sensor 1031 is located on a first side of acoustic device 100 facing the front of the user, sound sensor 1032 is located on a second side of acoustic device 100 facing the rear of the user, and sound sensor 1033 is located on a third side of acoustic device 100 facing the ground. Thus, when the ambient noise is emitted from a noise source in front of the user, the phase of the ambient noise reaching the sound sensor 1031 (or the phase of the individual ambient noise signal measured by the sound sensor 1031) leads the phase of the ambient noise reaching the sound output end of the speaker 102. When the ambient noise is emitted by a noise source behind the user, the phase of the ambient noise reaching the sound sensor 1032 (or the phase of the individual ambient noise signal measured by the sound sensor 1032) leads the phase of the ambient noise reaching the sound outlet end of the speaker 102. When the ambient noise is emitted by a noise source below the acoustic device, the phase of the ambient noise reaching the sound sensor 1033 (or the phase of the individual ambient noise signal measured by the sound sensor 1033) leads the phase of the ambient noise reaching the sound outlet end of the speaker 102. In some embodiments, the 3 sound sensors may be distributed in a triangular shape at the acoustic zero position of the speaker 102. In this way, the signals collected by the 3 sound sensors do not contain leakage signals from the loudspeaker 102, so that the active noise reduction effect is improved.

It should be noted that fig. 10 and fig. 11 are only two possible distribution manners. In practical designs, the N sound sensors may also be distributed in other ways, which are not illustrated here. In addition, the present application is not limited to the value of N, for example, the value of N may be equal to 4, 5 or any other integer.

In some embodiments, the N acoustic sensors may be arranged in an array, for example, a linear array, a planar array, a spherical array, or other arrays. The arrangement in the array manner is also beneficial to reducing the complexity of signal processing in the noise reduction circuit 105, so as to improve the active noise reduction performance.

At least some of the N sound sensors may be omni-directional microphones. The omnidirectional microphone has higher sensitivity to all directions of environmental noise, and can collect the environmental noise in any direction. At least some of the N sound sensors may also be directional microphones. The directional microphone is only able to collect ambient noise in a given direction. For example, as shown in fig. 10, the directivity of the sound sensor 1031 may be in front of the user and configured to collect the environmental noise transmitted from the front of the user, and the directivity of the sound sensor 1032 may be in back of the user and configured to collect the environmental noise transmitted from the back of the user. The directional microphones described above may include, but are not limited to: a heart-type directional microphone, a near-heart-type directional microphone, or other directional microphones. The directivities of the directional microphones to different frequencies may be the same or different.

In the case that the first sound sensor module 103 includes N sound sensors, the present application provides an active noise reduction method P300, where the noise reduction circuit 105 may assign weights to the N sound sensors when performing active noise reduction, so that the first sound sensor module 103 has phase-leading property in any direction. According to the scheme, the causality of feedforward noise reduction is improved, and then the active noise reduction effect can be improved. The active noise reduction method P300 may be independently applied to the acoustic device 100 provided in the present application, or may be combined with other active noise reduction methods described in other parts herein.

Fig. 12 shows a flowchart of yet another active noise reduction method P300 provided in accordance with an embodiment of the present description. The active noise reduction method P300 may be performed by the noise reduction circuit 105 in the acoustic device 100. For example, when the noise reduction circuit 105 adopts the structure shown in fig. 2, the processor 107 in the noise reduction circuit 105 may read an instruction set stored in its local storage medium and then execute the active noise reduction method P300 described in the present specification according to an instruction of the instruction set. As shown in fig. 12, the active noise reduction method P300 may include:

S31: a target direction from which the ambient noise is coming is determined.

The target direction refers to the direction from which the environmental noise comes, that is, the direction of noise source 300. In some embodiments, the direction of the ray directed from the target point on speaker 102 to noise source 300 may be referred to as the target direction.

In some embodiments, the noise reduction circuit 105 may acquire N individual ambient noise signals acquired by the N sound sensors, and estimate a target direction from which the ambient noise comes based on the N individual ambient noise signals. In some embodiments, the noise reduction circuit 105 may obtain the target direction by performing a full-band direction of arrival (Direction Of Arrival, DOA) analysis on the N individual ambient noise signals. In this case, the target direction indicates an incoming wave direction of the environmental noise of the full frequency band (i.e., the overall environmental noise).

It should be noted that the present application is not limited to the DOA algorithm, and may use one or more of a signal parameter estimation (ESTIMATING SIGNAL PARAMETER VIA Rotational Invariance Techniques, ESPRIT) algorithm, a multiple signal classification (Multiple Signal Classification, MUSIC) algorithm, etc. based on a rotation invariant technique, for example.

S32: and determining N weights corresponding to N sound sensors in the first sound sensor module based on the target direction, so that the phase of the comprehensive environmental noise signal measured by the first sound sensor module based on the N weights leads the phase of the environmental noise reaching the sound outlet end of the loudspeaker.

In some embodiments, the integrated ambient noise signal is a weighted sum of N individual ambient noise signals acquired by N sound sensors based on the N weights.

An example is illustrated in connection with fig. 10. The first acoustic sensor module 103 includes an acoustic sensor 1031 and an acoustic sensor 1032 therein. The individual environmental noise signals collected by the sound sensor 1031 are: The individual environmental noise signals collected by the sound sensor 1032 are: /(I)

Assuming that the weight of the sound sensor 1031 is α ₁ and the weight of the sound sensor 1032 is α ₂, the integrated environmental noise signal measured by the first sound sensor module 103 based on the above two weights may be expressed as:

the phase of the integrated ambient noise signal may be expressed as:

As can be seen, the noise reduction circuit 105 may set weights for the N sound sensors, respectively, based on the target direction, so that the phase of the above-described integrated noise signal leads the phase of the ambient noise reaching the sound outlet end of the speaker 102.

In some embodiments, the weight corresponding to the ith sound sensor is related to the leading condition of the phase of the individual ambient noise signal acquired by the ith sound sensor. For example, the more advanced the phase of the individual ambient noise signal acquired by the i-th sound sensor is compared to the phase of the ambient noise arriving at the sound output end of the speaker 102, the greater the weight corresponding to the i-th sound sensor, and conversely, the less the weight corresponding to the i-th sound sensor. Wherein i is any positive integer less than or equal to N.

In some embodiments, assuming that the direction of the ith sound sensor relative to the target point on speaker 102 and the angle between the target direction is θ _i, the weight corresponding to the ith sound sensor is inversely related to the θ _i. That is, the smaller θ _i (which is to say that the smaller the deviation between the direction of the sound sensor with respect to the target point and the target direction is), the larger the weight is, the larger θ _i (which is to say that the larger the deviation between the direction of the sound sensor with respect to the target point and the target direction is), the smaller the weight is. Wherein i is any positive integer less than or equal to N.

As illustrated in connection with fig. 10, assuming that the environmental noise comes from the front of the user, the weight of the sound sensor 1031 is greater than that of the sound sensor 1032, so that the sound sensor 1031 mainly plays a role in active noise reduction, and phase-lead can be ensured. Assuming that the environmental noise comes from the rear of the user, the weight of the sound sensor 1032 is greater than that of the sound sensor 1031, so that the sound sensor 1032 mainly plays a main role in active noise reduction, and phase-lead can be ensured.

S33: and generating a first noise elimination signal based on the N individual environmental noise signals acquired by the N sound sensors and the N weights.

In some embodiments, the noise reduction circuit 105 may include N feedforward filters in one-to-one correspondence with N sound sensors. Wherein the ith feedforward filter is coupled to the ith sound transducer and the speaker 102 and is configured to filter the individual ambient noise signal collected by the ith sound transducer. And i is any positive integer less than or equal to N. That is, the N feedforward filters in the noise reduction circuit 105 are in a parallel relationship.

Because N feedforward filters are in parallel connection, the order of the filters cannot be increased and delay cannot be increased in the active noise reduction process. In addition, on the basis, the N feedforward filters in parallel relation also contribute to increasing the filtering complexity, for example, the N feedforward filters can be responsible for noise reduction of different frequency bands, so that the feedforward noise reduction capability is enhanced.

Fig. 13 shows a schematic diagram of the active noise reduction principle of another acoustic device provided according to an embodiment of the present disclosure. As shown in fig. 13, the noise reduction circuit includes a feedforward filter h51 and a feedforward filter h52, assuming that the first acoustic sensor module 103 includes an acoustic sensor 1031 and an acoustic sensor 1032. The feedforward filter h51 is connected to the sound sensor 1031 and the speaker 102, and the feedforward filter h52 is connected to the sound sensor 1032 and the speaker 102.

Continuing to refer to fig. 13, assume:

The transfer function between the sound emitted from noise source 300 and the audio signal measured by sound sensor 1031 is denoted as h11;

The transfer function between the sound from noise source 300 and the audio signal measured by sound sensor 1032 is denoted as h12;

the acoustic transfer function between the sound emitted by the speaker 102 to the eardrum 202 is noted as h7; and

The acoustic transfer function between the sound emitted by noise source 300 and eardrum 202 is denoted as h8.

The noise signal from noise source 300 is denoted as S0; the individual environmental noise signal collected by the sound sensor 1031 is denoted as S11; the individual environmental noise signal collected by the sound sensor 1032 is noted as S12; the noise cancellation signal from speaker 102 is denoted S3; and the noise signal received by the eardrum 202 is denoted S4.

By the acoustic transfer process shown in fig. 13, the following relationship exists among the above S0, S11, S12, S3, and S4:

s4=s0+s3+h7 equation (0)

S3=s11+s12+h52 equation (7)

S11=s0×h11 equation (8)

S12=s0×h12 equation (9)

Substituting the formula (8) and the formula (9) into the formula (7) results in:

S3=s0×h11+s0+h12×h52 equation (10)

Substituting formula (10) into formula (0) to obtain:

s4=s0+h8+s0 (h11+h51+h12+h52) h7 equation (11)

As can be seen from equation (11), the feedforward noise reduction effect is determined by both h51 and h 52.

In some embodiments, when the noise reduction circuit 105 actively reduces noise, the filtering parameters of the feedforward filter h51 may be adjusted based on the weight of the sound sensor 1031, and the individual environmental noise signal S11 collected by the sound sensor 1031 may be filtered by the adjusted feedforward filter h51 to generate an individual noise cancellation signal. The noise reduction circuit 105 may adjust the filtering parameter of the feedforward filter h52 based on the weight of the sound sensor 1032, and filter the individual environmental noise signal S12 acquired by the sound sensor 1032 through the adjusted feedforward filter h52 to generate an individual noise cancellation signal. Further, the noise reduction circuit 105 synthesizes the two individual noise cancellation signals generated by the two feedforward filters to obtain a first noise cancellation signal.

In some embodiments, the foregoing adjustment of the filtering parameters of the feedforward filter h51 or the feedforward filter h52 may include: the filter gain of the feedforward filter h51 or the feedforward filter h52 is adjusted. For example, the current filter gain of the feedforward filter h51 may be multiplied by the weight of the sound sensor 1031 to obtain the filter gain adjusted by the feedforward filter h 51. The weights of the sound sensor 1032 may be multiplied by the current filter gain of the feedforward filter h52 to obtain an adjusted filter gain of the feedforward filter h 52.

It should be appreciated that the noise reduction circuit 105 adjusts the filtering parameters of the N feedforward filters based on the N weights, so that in the active noise reduction process, the sound sensor with higher weight (the sound sensor with higher phase lead) and the feedforward filter corresponding thereto have higher contribution to the overall noise reduction, and the sound sensor with lower weight (the sound sensor with lower phase lead) and the feedforward filter corresponding thereto have lower contribution to the overall noise reduction, so that the active noise reduction effect can be improved.

In some embodiments, the N sound sensors may be N directional microphones having different directivities. With continued reference to fig. 13, the directivity of the sound sensor 1031 is assumed to be in front of the user, and the directivity of the sound sensor 1032 is assumed to be in rear of the user. When the ambient noise comes from the front of the user, the directionality of the two sound sensors makes h11 much greater than h12 (i.e., h11 > h 12), and according to the above formula (11), it can be seen that the sound sensor 1031 mainly acts during the active noise reduction process, so that the first sound sensor module 103 has phase lead, and thus the active noise reduction effect can be improved. When the ambient noise comes from the rear of the user, the directionality of the two sound sensors makes h11 much smaller than h12 (i.e., h11< < h 12), and according to the above formula (11), it is seen that the sound sensor 1032 mainly acts during the active noise reduction process, and therefore, the first sound sensor module 103 has phase lead, so that the active noise reduction effect can be improved.

Therefore, under the condition that the N sound sensors have different directivities, so that the optimal sound sensor is automatically selected in the active noise reduction process, and the phase lead of the first sound sensor module in all directions can be realized without adjusting the filtering parameters of the feedforward filter.

S34: the first noise cancellation signal is sent to a speaker to cause the speaker to convert the first noise cancellation signal to first noise cancellation audio to reduce the volume of the ambient noise at the eardrum.

It should be understood that S31 to S34 described above describe that the incoming wave direction estimation is performed on the environmental noise of the full frequency band, and the active noise reduction of the full frequency band is performed based on the estimated target direction. In some embodiments, the noise reduction circuit 105 may also estimate the molecular frequency band when estimating the target direction. For example, the full frequency band is divided into M sub-bands, and the environmental noise includes M sub-band noise corresponding to the M sub-bands. The noise reduction circuit 105 may estimate the directions of the incoming waves of the M subband noises for each subband. In this case, the target directions obtained in S31 include M incoming directions corresponding to M subbands. Note that the division method of M subbands is not limited in the present application. In some embodiments, the M subbands may include: low frequency band (e.g., 0-150 Hz), medium frequency band (e.g., 150-500 Hz), and high frequency band (e.g., 500-2000 Hz).

In some embodiments, the noise reduction circuit 105 may obtain N individual environmental noise signals collected by N sound sensors, and further estimate the incoming wave direction of the jth sub-band by: and respectively extracting the sub-band noise signals corresponding to the jth sub-band from the N individual environmental noise signals to obtain N sub-band noise signals corresponding to the jth sub-band, and performing DOA analysis on the N sub-band noise signals to obtain the incoming wave direction corresponding to the jth sub-band. Wherein j is any positive integer less than or equal to M.

After obtaining the M incoming wave directions corresponding to the M subbands, the noise reduction circuit 105 may perform active noise reduction on a per-subband basis, respectively. Specifically, the noise reduction circuit 105 determines N subband weights corresponding to the N sound sensors for the j-th subband based on the incoming direction corresponding to the j-th subband, so that the first sound sensor module 103 advances the phase of the synthesized subband noise signal measured based on the N subband weights and the phase of the environmental noise of the j-th subband reaching the sound output end of the speaker 102. The synthesized subband noise signals are signals obtained by carrying out weighted summation on subband noise signals corresponding to the jth subband, which are acquired by the N sound sensors, based on the N subband weights. Further, the noise reduction circuit 105 generates N individual subband noise canceling signals corresponding to the jth subband based on the subband noise signals corresponding to the jth subband acquired by the N sound sensors and the N subband weights. And the noise reduction circuit superimposes the N individual sub-band noise elimination signals to obtain a sub-band noise elimination signal corresponding to the j sub-band. Wherein j is any positive integer less than or equal to M. The reduction circuit 105 performs the above-described processes for the M subbands, respectively, resulting in M subband noise canceling signals corresponding to the M subbands. Further, the noise reduction circuit 105 sends the M subband noise cancellation signals to the speaker 102 to cause the speaker 102 to convert the M subband noise cancellation signals to noise cancellation audio to reduce the volume of ambient noise at the eardrum 202.

It should be appreciated that the active noise reduction process for each sub-band is similar to the active noise reduction process for the full band described above, and will not be repeated here. It should be noted that each feedforward filter may include M filter units corresponding to M subbands, and when active noise reduction is performed on the jth subband, a filter parameter corresponding to the jth filter unit in the feedforward filter may be adjusted based on the weight, for example, a filter gain corresponding to the jth filter unit may be adjusted.

Fig. 14 shows a schematic diagram of a set of frequency response curves provided in accordance with an embodiment of the present description. As shown in fig. 14, a curve 141 illustrates the frequency response of the acoustic device 100 using a single sound sensor FF1 and matching the feedforward filter, a curve 142 illustrates the frequency response of the acoustic device 100 using a single sound sensor FF2 and matching the feedforward filter, and a curve 143 illustrates the frequency response of the acoustic device 100 using both the sound sensor FF1 and the sound sensor FF2 and matching the two parallel feedforward filters. As can be seen from the curves 141 and 142, the individual sound sensor FF1 and the individual sound sensor FF2 each have a noise reduction effect in different frequency bands. As can be seen from the curve 143, the combination of the sound sensor FF1 and the sound sensor FF2 can provide a noise reduction effect in a wider frequency band and a deeper noise reduction depth.

As previously described, in an open acoustic device, there may be a leakage signal (i.e., a leakage signal from the speaker 102) in the ambient noise signal collected by the acoustic sensor. The acoustic device 100 can reduce the above-described leakage to some extent by providing a plurality of sound sensors in the first sound sensor 103. Fig. 15 shows a schematic diagram of yet another set of frequency response curves provided in accordance with an embodiment of the present description. As shown in fig. 15, a curve 153 illustrates the frequency response in the case where the acoustic device 100 employs both the acoustic sensor FF1 and the acoustic sensor FF2 in combination with two parallel feedforward filters for noise reduction. Here, curve 151 illustrates the frequency response of FF1 and its corresponding feedforward filter, and curve 152 illustrates the frequency response of FF2 and its corresponding feedforward filter. As can be seen from fig. 15, in the case of using two sound sensors, the feedforward filter gain required for each sound sensor is significantly smaller than that required when using a single sound sensor to achieve the same filtering effect. The reduction of the feedforward filter gain can reduce leakage, so that the problems of system divergence caused by leakage, noise increase caused by wearing acoustic equipment by partial users and the like are avoided.

In summary, in the active noise reduction method P300 provided in the present disclosure, when the first sound sensor module 103 includes N sound sensors, the noise reduction circuit 105 may determine N weights corresponding to the N sound sensors based on the target direction from which the environmental noise comes when performing active noise reduction, so that the phase of the integrated environmental noise signal measured by the first sound sensor module 103 based on the N weights leads to the phase of the environmental noise reaching the sound output end of the speaker. Then, the noise reduction circuit 105 generates a first noise cancellation signal based on the N individual environmental noise signals acquired by the N sound sensors and the N weights, and transmits the first noise cancellation signal to the speaker 102. Therefore, according to the scheme, the N sound sensors are introduced and weight is distributed to the N sound sensors, so that no matter which direction ambient noise comes from, the first sound sensor module 103 can be guaranteed to have phase leading performance relative to the sound outlet end of the loudspeaker 102, the causality of feedforward noise reduction is improved, the active noise reduction effect is improved, and the high-frequency noise reduction performance is improved. In addition, the use of multiple sound sensors can reduce gain compared to a single sound sensor, thereby reducing leakage in certain frequency bands (e.g., high frequencies) in an open scene, and avoiding system divergence problems due to leakage in the frequency bands, noise enhancement problems caused by wearing acoustic equipment by some users, and the like. Furthermore, the incoming wave direction is estimated by taking the sub-frequency bands as granularity, and active noise reduction is carried out on each sub-frequency band, so that the noise reduction depth of each sub-frequency band is improved, and the active noise reduction effect is further improved.

Generally, the acoustic device 100 performs active noise reduction in a full frequency band range based on a pre-designed noise reduction parameter after turning on an active noise reduction function. In practical applications, the above-mentioned pre-designed noise reduction parameters are generally not suitable for actively reducing noise in various external environments due to various external environments in which the acoustic device 100 is located. For example, the noise reduction effect of an acoustic device may be poor in some special external environments, or there may be a case where the speaker 102 breaks down.

To this end, the noise reduction circuit 105 may provide a plurality of noise reduction modes. In this way, in the active noise reduction process, the noise reduction circuit 105 can adaptively select a target noise reduction mode among a plurality of noise reduction modes based on the noise condition of the external environment, and execute the target noise reduction mode. Wherein adaptively selecting the target noise reduction mode means that the noise reduction mode can be autonomously, flexibly, intelligently, and/or adaptively switched according to the noise condition of the external environment. It should be appreciated that the above-described process of switching the noise reduction mode is performed automatically by the noise reduction circuit 105 without manual intervention by the user.

In some embodiments, the plurality of noise reduction modes may include: at least one of a passive noise reduction mode, a tamper noise reduction mode, a narrowband noise reduction mode, or a normal noise reduction mode.

Wherein in the passive noise reduction mode, the active noise reduction function of the acoustic device 100 is turned off.

In the normal noise reduction mode, the active noise reduction function of the acoustic device 100 is turned on, and the noise reduction circuit 105 performs active noise reduction in a full frequency band range based on at least one of the first sound signal or the second sound signal using a noise reduction parameter designed in advance.

In the narrowband noise reduction mode, the active noise reduction function of the acoustic device 100 is turned on. The active noise reduction process comprises the following steps: the noise reduction circuit 105 determines a target frequency band, within which the energy concentration exceeds a preset threshold, based on the first sound signal. The energy concentration in the target frequency band refers to the concentration of noise signal energy in the target frequency band. In some embodiments, the bandwidth corresponding to the target frequency band is less than a preset bandwidth, and thus the target frequency band may be referred to as a narrowband. Further, the noise reduction circuit 105 may actively reduce noise in a target frequency band (narrow band) based on at least one of the first sound signal or the second sound signal.

In some embodiments, after determining the target frequency band, the noise reduction circuit 105 may adjust the noise reduction parameters of the noise reduction circuit 105 based on the target frequency band, the adjusted noise reduction parameters may specify that the target frequency band is actively noise reduced (e.g., the noise reduction depth of the target frequency band is greater than the noise reduction depths of other frequency bands), or the adjusted noise reduction parameters may specify that only the target frequency band is actively noise reduced and not the other frequency bands. In some embodiments, the above-described "adjusting the noise reduction parameters of the noise reduction circuit 105" may include: the full band filter in the noise reduction circuit 105 is converted into a narrow band filter. According to the embodiment, the noise reduction depth in the target frequency band can be increased by adjusting the noise reduction parameters based on the target frequency band, and the noise reduction effect in the target frequency band is improved.

In the anti-rattle noise reduction mode, the active noise reduction function of the acoustic device 100 is turned on. The active noise reduction process comprises the following steps: the noise reduction circuit 105 generates a noise cancellation signal based on at least one of the first sound signal or the second sound signal, and causes the amplitude of the noise cancellation signal to lie within the amplitude range supported by the speaker 102. Further, the noise reduction circuit 105 transmits a noise cancellation signal to the speaker 102 to cause the speaker 102 to convert the noise cancellation signal into noise cancellation audio to reduce the volume of ambient noise at the eardrum 202. The amplitude range refers to a signal amplitude range supported by the speaker 102 to play normally without breaking sound (brookfen sound). The broken sound means that the vibration of the loudspeaker diaphragm exceeds the linear range, so that the phenomenon of serious sound aliasing is caused. When the amplitude of the signal input to the speaker 102 exceeds the above amplitude range, the speaker 102 may be caused to break down. When the amplitude of the signal input to the speaker 102 is within the amplitude range, the speaker 102 is not caused to break. It should be appreciated that since the noise reduction circuit 105 ensures that the amplitude of the noise cancellation signal is within the range of the amplitude supported by the speaker 102 when generating the noise cancellation signal, the speaker 102 can be prevented from breaking.

In some embodiments, the noise reduction circuit 105 may generate the noise cancellation signal such that the amplitude of the noise cancellation signal is within the range of amplitudes supported by the speaker 102 in the following manner: the noise reduction circuit 105 filters at least one of the first sound signal or the second sound signal to obtain a candidate noise cancellation signal. The filtering process is described in the relevant section above, and will not be described here. Further, the noise reduction circuit 105 corrects the amplitude of the candidate noise cancellation signal based on the amplitude range so that the corrected amplitude is within the amplitude range, and takes the corrected signal as the noise cancellation signal. In some embodiments, the output of the noise reduction circuit 105 (i.e., at the interface of the noise reduction circuit 105 and the speaker 102) may be provided with a Dynamic Range Controller (DRC) engine. The dynamic range controller is configured to adjust the amplitude of the input signal such that the amplitude of the output signal is within the amplitude range. In this case, after the noise reduction circuit 105 obtains the candidate noise cancellation signal, the candidate noise cancellation signal is input to the dynamic range controller, and the amplitude of the candidate noise cancellation signal is corrected by the dynamic range controller, so that noise cancellation noise is obtained.

In this manner, the noise reduction circuit 105 does not need to adjust the original noise reduction parameters, but only needs to add a post amplitude correction link (for example, adding a dynamic range controller), so as to avoid the speaker 102 from breaking.

In some embodiments, the noise reduction circuit 105 may generate the noise cancellation signal such that the amplitude of the noise cancellation signal is within the range of amplitudes supported by the speaker 102 in the following manner: the noise reduction circuit 105 adjusts a filtering gain corresponding to the noise reduction circuit 105 based on the first sound signal, so that the amplitude of the output signal obtained after filtering is within the amplitude range. Further, the noise reduction circuit 105 filters at least one of the first sound signal or the second sound signal based on the adjusted noise reduction parameter to obtain the noise cancellation signal.

In this manner, the noise reduction circuit 105 can make the amplitude of the noise cancellation signal within the amplitude range by only adjusting the filter gain, without changing the circuit structure of the noise reduction circuit 105.

In some embodiments, in the adjusted filter gains, a first filter gain corresponding to a first preset frequency band is smaller than a second filter gain corresponding to a second preset frequency band. In some embodiments, the frequencies in the first preset frequency band are lower than the frequencies in the second preset frequency band. In some embodiments, the frequency in the first preset frequency band is lower than a preset frequency, where the preset frequency may be 500Hz, 200Hz, 150Hz, or other frequency values. In some embodiments, the first preset frequency band may be a low frequency band (for example, a frequency band with a frequency less than 150 Hz). Because the first preset frequency band corresponds to a smaller filtering gain, the amplitude of the noise-canceling signal after filtering corresponding to the first preset frequency band can be smaller, so that the loudspeaker 102 is prevented from breaking in the first preset frequency band.

In some embodiments, the noise reduction circuit 105 may reduce the first filter gain corresponding to the first preset frequency band based on the default filter gain while maintaining the second filter gain corresponding to the second preset frequency band unchanged when adjusting the filter gain. In this way, the speaker 102 can be prevented from breaking sound without reducing the noise reduction effect corresponding to the second preset frequency band.

In the case that the acoustic device 100 provides multiple noise reduction modes, the active noise reduction method P400 is provided, and the noise reduction modes suitable for the current environment can be adaptively switched based on the noise condition of the current environment, so that the acoustic device 100 can have better noise reduction effects in different environments. The active noise reduction method P400 may be independently applied to the acoustic device 100 provided in the present application, or may be combined with other active noise reduction methods described in other parts herein.

Fig. 16 shows a flowchart of yet another active noise reduction method P400 provided in accordance with an embodiment of the present description. The active noise reduction method P400 may be performed by the noise reduction circuit 105 in the acoustic device 100. For example, the processor 107 in the noise reduction circuit 105 may read the instruction set stored in its local storage medium and then execute the active noise reduction method P400 described in this specification according to the instruction of the instruction set. As shown in fig. 16, the active noise reduction method P400 may include:

s41: a first sound signal is obtained from a first sound sensor module.

S42: a target noise reduction mode is adaptively selected among a plurality of noise reduction modes of an acoustic device based on the first sound signal.

In some embodiments, the noise reduction circuit 105 may adaptively select the target noise reduction mode among the plurality of noise reduction modes based on at least one of the intensity or bandwidth type of the first sound signal. The bandwidth types of the first sound signal may be classified into two types as follows: narrowband types and non-narrowband types. The narrowband type indicates that the bandwidth occupied by the first sound signal is smaller than a preset bandwidth. The narrowband type of signal energy is concentrated in a narrower frequency band than the non-narrowband type.

In some embodiments, the process of adaptively selecting the target noise reduction mode by the noise reduction circuit 105 may include at least one of S42-1, S42-2, S42-3 described below.

S42-1: determining that the intensity of the first sound signal is less than or equal to a second intensity threshold, and selecting a negative noise reduction mode from the plurality of noise reduction modes.

Wherein the second intensity threshold may correspond to an upper limit of noise intensity in a quieter environment. For example, the second intensity threshold may be 40dB. That is, when the noise intensity of the external environment is small (e.g., less than 40 dB), the noise reduction circuit 105 selects the passive noise reduction mode, turning off the active noise reduction function. This may reduce the power consumption of the acoustic device 100.

S42-2: and determining that the intensity of the first sound signal is greater than or equal to a first intensity threshold, and selecting a sound breaking prevention noise reduction mode from the plurality of noise reduction modes.

Wherein the first intensity threshold is greater than the second intensity threshold. For example, the first intensity threshold may be 90dB. The noise reduction circuit 105 may select the anti-aliasing noise reduction mode when the noise of the external environment is high (e.g., greater than or equal to 90 dB). This can avoid the speaker 102 from breaking sound.

S42-3: determining that the intensity of the first sound signal is greater than a second intensity threshold, and the bandwidth type of the first sound signal is a narrowband type, and selecting a narrowband noise reduction mode from the plurality of noise reduction modes.

Wherein, the "the intensity of the first sound signal is greater than the second intensity threshold" is a condition for turning on the active noise reduction function, and on the basis of this, if the bandwidth type of the first sound signal is a narrowband type, the noise reduction circuit 105 selects a narrowband noise reduction mode. Therefore, the active noise reduction can be performed only for the target frequency band in which the energy of the first sound signal is concentrated, and the active noise reduction is not needed in the whole frequency band range, so that the noise reduction depth in the target frequency band can be increased, and the active noise reduction effect is improved.

In some embodiments, the decision logic of the noise reduction circuit 105 to adaptively select the target noise reduction mode may be as follows: the noise reduction circuit 105 first determines whether the intensity of the first sound signal is less than a second intensity threshold, and if so, selects a passive noise reduction mode. If not, the active noise reduction function is started. After that, the noise reduction circuit 105 determines whether or not the following two conditions are satisfied, condition 1: the intensity of the first sound signal is greater than or equal to the first intensity threshold, condition 2: the bandwidth type of the first sound signal is a narrowband type. The judgment result at this time includes the following four cases: if only the condition 1 is met, selecting a sound breaking prevention and noise reduction mode; if only condition 2 is met, selecting a narrow-band noise reduction mode; if both the condition 1 and the condition 2 are satisfied, the anti-noise reduction mode and the narrow-band noise reduction mode can be selected at the same time, and if both the condition 1 and the condition 2 are not satisfied, the common noise reduction mode is selected.

In some embodiments, when the first sound signal includes both the ambient noise signal and the leakage signal, the noise reduction circuit 105 may first attenuate a component of the leakage signal in the first sound signal to generate the quasi-ambient noise signal, and further adaptively select the target noise reduction mode among the plurality of noise reduction modes based on the quasi-ambient noise signal. The above manner of reducing the component of the leakage signal in the first audio signal is described in the foregoing, and will not be described herein.

The noise reduction circuit 105 reduces the component of the leakage signal in the first sound signal, so that the obtained quasi-ambient noise signal is closer to the actual ambient noise, and therefore, the target noise reduction mode is adaptively selected based on the quasi-ambient noise signal, so that the selected target noise reduction mode is more consistent with the current environment, and the noise reduction effect is improved.

S43: and executing the target noise reduction mode.

In some embodiments, the acoustic device 100 operates in a feed-forward noise reduction mode, and the noise reduction circuit 105 performs a target noise reduction mode based on the first sound signal. In some embodiments, the acoustic device 100 operates in a feedback noise reduction mode, and the noise reduction circuit 105 performs a target noise reduction mode based on the second sound signal. In some embodiments, the acoustic device 100 operates in a hybrid noise reduction mode, and the noise reduction circuit 105 performs a target noise reduction mode based on the first sound signal and the second sound signal.

In summary, the active noise reduction method P400 provided in the present disclosure may adaptively adjust the noise reduction mode based on the noise condition of the external environment where the acoustic device 100 is located, so that the active noise reduction process of the acoustic device 100 better conforms to the noise condition of the current environment, and is helpful for improving the overall performance of the acoustic device 100. For example, when the noise of the current environment is low, the acoustic device 100 may turn off the active noise reduction function to reduce power consumption; when the noise of the current environment is high, the acoustic device 100 can select the anti-sound breaking and noise reduction mode to avoid sound breaking of the loudspeaker 102; when the noise of the current environment is of a narrowband type, the acoustic device 100 may select a narrowband noise reduction mode to increase the noise reduction depth and enhance the noise reduction effect.

In the case where the acoustic device 100 provides multiple noise reduction modes, the present application also provides another active noise reduction method that may be performed by the noise reduction circuit 105. In the active noise reduction method, the noise reduction circuit 105 may acquire a user instruction, and select a target noise reduction mode from a plurality of noise reduction modes according to the user instruction, so as to execute the target noise reduction mode. For example, an interactive control may be provided on the acoustic device 100 through which a user may switch different noise reduction modes. For another example, the acoustic device 100 may provide an interactive interface that may be presented on a screen of the acoustic device 100 or on a target device communicatively coupled to the acoustic device 100, through which a user may select different noise reduction modes. In some embodiments, the user's instructions may indicate a particular noise reduction mode, such that the noise reduction circuit 105 may determine the noise reduction mode indicated by the instructions as the target noise reduction mode. In some embodiments, the user's instruction may specifically indicate an environmental noise condition in which the user is located, and the noise reduction circuit 105 may select the target noise reduction mode from the plurality of noise reduction modes based on the environmental noise condition indicated by the instruction. Therefore, the user can autonomously select a proper active noise reduction mode according to own preference and/or the current environment noise condition, so that the personalized requirements of different users are met.

In another aspect, the present disclosure provides a non-transitory storage medium storing at least one set of executable instructions for active noise reduction. When executed by a processor, the executable instructions direct the processor to perform the steps of the active noise reduction method described herein. In some possible implementations, aspects of the specification can also be implemented in the form of a program product including program code. The program code is for causing the acoustic device 100 to perform the steps of the active noise reduction method described in the present specification when the program product is run on the acoustic device 100. The program product for implementing the above method may employ a portable compact disc read only memory (CD-ROM) comprising program code and may run on the acoustic device 100. However, the program product of the present specification is not limited thereto, and in the present specification, the readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system. The program product may employ any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. The readable storage medium can be, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples of the readable storage medium include: an electrical connection having one or more wires, a portable disk, a hard disk, random Access Memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. The computer readable storage medium may include a data signal propagated in baseband or as part of a carrier wave, with readable program code embodied therein. Such a propagated data signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination of the foregoing. A readable storage medium may also be any readable medium that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a readable storage medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing. Program code for carrying out operations of the present specification may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the acoustic device 100, partly on the acoustic device 100, as a stand-alone software package, partly on the acoustic device 100, partly on a remote computing device, or entirely on the remote computing device.

The foregoing describes specific embodiments of the present disclosure. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims can be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

In view of the foregoing, it will be evident to a person skilled in the art that the foregoing detailed disclosure may be presented by way of example only and may not be limiting. Although not explicitly described herein, those skilled in the art will appreciate that the present description is intended to encompass various adaptations, improvements, and modifications of the embodiments. Such alterations, improvements, and modifications are intended to be proposed by this specification, and are intended to be within the spirit and scope of the exemplary embodiments of this specification.

Furthermore, certain terms in the present description have been used to describe embodiments of the present description. For example, "one embodiment," "an embodiment," and/or "some embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present description. Thus, it is emphasized and should be appreciated that two or more references to "an embodiment" or "one embodiment" or "an alternative embodiment" in various portions of this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined as suitable in one or more embodiments of the invention.

It should be appreciated that in the foregoing description of embodiments of the present specification, various features have been combined in a single embodiment, the accompanying drawings, or description thereof for the purpose of simplifying the specification in order to assist in understanding one feature. However, this is not to say that a combination of these features is necessary, and it is entirely possible for a person skilled in the art to label some of the devices as separate embodiments to understand them upon reading this description. That is, embodiments in this specification may also be understood as an integration of multiple secondary embodiments. While each secondary embodiment is satisfied by less than all of the features of a single foregoing disclosed embodiment.

Each patent, patent application, publication of patent application, and other materials, such as articles, books, specifications, publications, documents, articles, etc., cited herein are hereby incorporated by reference. All matters are to be interpreted in a generic and descriptive sense only and not for purposes of limitation, except for any prosecution file history associated therewith, any and all matters not inconsistent or conflicting with this document or any and all matters not complaint file histories which might have a limiting effect on the broadest scope of the claims. Now or later in association with this document. For example, if there is any inconsistency or conflict between the description, definition, and/or use of terms associated with any of the incorporated materials, the terms in the present document shall prevail.

Finally, it is to be understood that the embodiments of the application disclosed herein are illustrative of the principles of the embodiments of the present specification. Other modified embodiments are also within the scope of this specification. Accordingly, the embodiments disclosed herein are by way of example only and not limitation. Those skilled in the art can adopt alternative arrangements to implement the application in the specification based on the embodiments in the specification. Therefore, the embodiments of the present specification are not limited to the embodiments precisely described in the application.

Claims

1. An open wearable acoustic device, comprising:

A support;

a speaker physically connected to the support, the speaker forming an open space with an eardrum of a user when the acoustic device is worn on the user's head;

A first sound sensor module, in physical connection with the support, configured to collect a first sound and generate a first sound signal, the first sound signal comprising: an ambient noise signal from ambient noise and a leakage signal from the speaker; and

Noise reduction circuitry configured to:

the first acoustic signal is acquired from the first acoustic sensor module,

Generating a quasi-ambient noise signal by clipping a component of the leakage signal in the first sound signal,

Generating a first noise cancellation signal based on the quasi-ambient noise signal, and

The first noise cancellation signal is sent to the speaker to cause the speaker to convert the first noise cancellation signal to first noise cancellation audio to reduce the volume of ambient noise at the eardrum.

2. The acoustic device of claim 1 wherein the first acoustic sensor module is remote from the eardrum relative to the speaker.

3. The acoustic device of claim 1, wherein to generate the quasi-ambient noise signal, the noise reduction circuit is to:

acquiring an input signal corresponding to the loudspeaker;

Providing a first gain for the input signal to obtain a first gain signal, wherein the first gain is a transfer function between the loudspeaker and the first sound sensor module; and

And obtaining the first sound signal from the first sound sensor module, and subtracting the first gain signal from the first sound signal to obtain the quasi-environmental noise signal.

4. The acoustic device of claim 3, wherein the noise reduction circuit is further configured to:

transmitting a test audio signal to the loudspeaker so that the loudspeaker emits corresponding test audio, wherein the test audio is collected by the first sound sensor module;

Acquiring an acquired audio signal acquired by the first sound sensor module; and

And determining the transfer function according to the test audio signal and the collected audio signal.

5. The acoustic device of claim 1, wherein the noise reduction circuit includes a feedforward filter therein, wherein to generate the first noise cancellation signal, the noise reduction circuit:

inputting the quasi-ambient noise signal into the feedforward filter, and

Filtering the quasi-ambient noise signal by the feedforward filter to obtain the first noise cancellation signal,

Wherein the feedforward filter is configured to adjust at least one of a gain or a phase of the quasi-ambient noise signal such that the resulting first noise cancellation signal is capable of being offset with at least a portion of ambient noise at the eardrum.

6. The acoustic device of claim 1, wherein a distance between the first acoustic sensor module and an acoustic zero position of the speaker is within a non-zero preset range.

7. The acoustic device of claim 1, further comprising a second sound sensor module physically connected to the support and configured to collect a second sound and generate a second sound signal; and

The noise reduction circuit is further configured to:

the second sound signal is acquired from the second sound sensor module,

Generating a second noise cancellation signal based on the second sound signal, and

The second noise cancellation signal is sent to the speaker to cause the speaker to convert the second noise cancellation signal to second noise cancellation audio to further reduce the volume of ambient noise at the eardrum.

8. The acoustic device of claim 7 wherein the second sound sensor module is proximate the eardrum relative to the speaker.

9. The acoustic device of claim 7, wherein to send the first and second noise cancellation signals to the speaker, the noise reduction circuit is to:

Synthesizing the first noise elimination signal and the second noise elimination signal to obtain a synthesized noise elimination signal; and

And sending the synthesized noise elimination signal to the loudspeaker.

10. The acoustic device of claim 7, wherein the noise reduction circuit includes a feedback filter therein, wherein to generate the second noise cancellation signal, the noise reduction circuit:

Inputting the second sound signal into the feedback filter; and

Filtering the second sound signal through the feedback filter to obtain the second noise elimination signal,

Wherein the feedback filter is configured to adjust at least one of a gain or a phase of the second sound signal such that the resulting second noise cancellation signal is capable of being offset with at least part of the ambient noise at the eardrum.

11. The acoustic device of claim 1, wherein the noise reduction circuit comprises:

At least one storage medium storing at least one instruction set for performing noise reduction; and

At least one processor in communication with the speaker, the first acoustic sensor module, and the at least one storage medium,

Wherein the at least one processor reads the at least one instruction set when the acoustic device is operating and performs according to an indication of the at least one instruction set:

acquiring the first sound signal from the first sound sensor,

12. The acoustic device of claim 1, wherein the acoustic device is one of an earpiece, a muffler, a hearing aid, and an acoustic glasses.

13. An active noise reduction method applied to the open wearable acoustic device of claim 1, the method comprising, by the noise reduction circuit:

acquiring the first sound signal from the first sound sensor module;

generating a quasi-ambient noise signal by clipping a component of the leakage signal in the first sound signal;

generating a first noise cancellation signal based on the quasi-ambient noise signal; and

14. The method of claim 13, wherein the first acoustic sensor module is remote from the eardrum relative to the speaker.

15. The method of claim 13, wherein the generating a quasi-ambient noise signal by clipping components of the leakage signal in the first sound signal comprises:

acquiring an input signal corresponding to the loudspeaker;

16. The method of claim 15, further comprising, by the noise reduction circuit:

17. The method of claim 13, wherein the noise reduction circuit includes a feedforward filter therein; and

The generating a first noise cancellation signal based on the quasi-ambient noise signal includes:

inputting the quasi-ambient noise signal into the feedforward filter, and

18. The method of claim 13, wherein the acoustic device further comprises a second sound sensor module physically connected to the support and configured to collect a second sound and generate a second sound signal; and

The method further includes, by the noise reduction circuit:

the second sound signal is acquired from the second sound sensor module,

19. The method of claim 18, wherein the second sound sensor module is proximate the eardrum relative to the speaker.

20. The method of claim 18, wherein the noise reduction circuit includes a feedback filter therein; and

The generating a second noise cancellation signal based on the second sound signal includes:

inputting the second sound signal into the feedback filter, and