CN113727234B - Wireless earphone with active noise reduction function and noise reduction method thereof - Google Patents
Wireless earphone with active noise reduction function and noise reduction method thereof Download PDFInfo
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- 210000000883 ear external Anatomy 0.000 claims description 10
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/10—Earpieces; Attachments therefor ; Earphones; Monophonic headphones
- H04R1/1083—Reduction of ambient noise
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1785—Methods, e.g. algorithms; Devices
- G10K11/17853—Methods, e.g. algorithms; Devices of the filter
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
- G10K2210/10—Applications
- G10K2210/108—Communication systems, e.g. where useful sound is kept and noise is cancelled
- G10K2210/1081—Earphones, e.g. for telephones, ear protectors or headsets
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Abstract
The disclosure relates to a wireless earphone with an active noise reduction function and a noise reduction method thereof, and belongs to the technical field of earphones. The earphone comprises an in-ear microphone, a loudspeaker, a feedforward filter and a controller, wherein the controller is configured to determine relevant parameters of a played prompt tone and a collected prompt tone and/or determine energy parameters of the collected prompt tone as current first parameters under the condition that the earphone is in the ear or active noise reduction is to be opened; the current filter parameters of the feedforward filter are determined based on the current first parameter and a predetermined correspondence between the first parameter and the filter parameters of the feedforward filter. Therefore, the current filter parameters of the feedforward filter can be rapidly determined through the prompt tone, so that a user can feel stable noise reduction effect in a short time, and the use experience of the user is improved.
Description
Technical Field
The present disclosure relates to the field of earphone technologies, and in particular, to a wireless earphone with an active noise reduction function and a noise reduction method thereof.
Background
With the improvement of social progress and the improvement of living standard of people, the earphone becomes an indispensable living article for people. The traditional wired earphone is connected with intelligent equipment (such as a smart phone, a notebook computer, a tablet computer and the like) through a wire, but the action of a wearer is limited, and particularly, the wired earphone is very inconvenient in sports occasions. Meanwhile, the winding, pulling and stethoscope effects of the earphone line all affect the user experience. The common Bluetooth headset cancels the connection between the headset and the wireless host, but the connection still exists between the left ear and the right ear. The active noise reduction earphone gradually goes into the life of people, so that people can obtain a relatively quiet environment in a noisy environment, and the principle is that the earphone actively emits sound waves with opposite phases to counteract the sound waves (feedforward) or an acoustic path (feedback) with feedback is added on a sound path to reduce the noise heard by the ears of the people.
At present, most active noise reduction methods of headphones are used for selecting filter coefficients according to noise scenes, wherein the noise scenes can comprise airplanes, restaurants, subways, streets and the like. The user sets a set of fixed noise reduction coefficients, such as feedforward and feedback filter coefficients, for the headphones by selecting different noise scenarios. When a user switches between multiple scenes, multiple selections of scenes are required to adjust the noise reduction coefficients, which greatly affects the user's use experience. Even in the same scene, noise conditions are not consistent, for example, subways in rush hour and midnight have completely different noise intensities, and it is obviously inappropriate to use the same noise reduction coefficient for the subways in different periods.
Secondly, the noise reduction effect of the earphone is greatly influenced by different wearing modes and auditory canal structures. Different users have different ear canal structures, and different wearing modes can enable different relative positions to be formed between the earphone and the human ear, and the influence of the generated gap on noise and the influence on in-ear echo are different. Even if the same user uses the same earphone, the positions of the earphone in the human ear are not completely consistent each time the user wears the earphone, and at this time, the current filter coefficient of the feedforward filter needs to be quickly determined. Obviously, the existing earphone cannot solve the above problems.
Disclosure of Invention
The present disclosure is provided to solve the above-mentioned problems occurring in the prior art. The wireless earphone with the active noise reduction function is needed, and the current filter parameters of the feedforward filter can be rapidly determined through the prompt tone, so that a user can feel a stable noise reduction effect in a short time, and the use experience of the user is improved.
According to a first aspect of the present disclosure, there is provided a wireless earphone having an active noise reduction function, the wireless earphone including an in-ear microphone, a speaker configured to play a cue sound in a case where the earphone is in the ear or active noise reduction is to be turned on, a feedforward filter, and a controller; the in-ear microphone is configured to collect a prompt tone in the case that an earphone is in the ear or active noise reduction is to be turned on; the controller is configured to determine relevant parameters of the played cue sound and the collected cue sound and/or determine energy parameters of the collected cue sound as current first parameters under the condition that the earphone is in the ear or active noise reduction is to be opened; the current filter parameters of the feedforward filter are determined based on the current first parameters and a predetermined correspondence between the first parameters and the filter parameters of the feedforward filter.
According to a second aspect of the present disclosure, there is provided a noise reduction method of a wireless earphone having an active noise reduction function, the wireless earphone including an in-ear microphone, a speaker, a feedforward filter, and a controller, the noise reduction method including playing a cue by the speaker and collecting the cue by the in-ear microphone in a case that the earphone is in the ear or active noise reduction is to be turned on; the controller determines the relevant parameters of the played prompt tone and the collected prompt tone and/or determines the energy parameter of the collected prompt tone as the current first parameter; determining, by a controller, a current filter parameter of the feedforward filter based on the current first parameter and a predetermined correspondence between the first parameter and a filter parameter of the feedforward filter; and the feedforward filter operates according to the determined current filter parameters.
According to the wireless earphone with the active noise reduction function, the current filter parameters of the feedforward filter can be rapidly determined through the prompt tone, so that a user can feel stable noise reduction effect in a short time, and the use experience of the user is improved. Meanwhile, the environmental sound is removed from the prompt sound collected by the in-ear microphone, so that the interference of the environmental sound to the prompt sound is reduced, the influence of the environmental sound on the processing of the prompt sound in the later stage can be reduced, and the noise reduction performance of the earphone is further improved.
Drawings
In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. The accompanying drawings illustrate various embodiments by way of example in general and not by way of limitation, and together with the description and claims serve to explain the disclosed embodiments. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Such embodiments are illustrative and not intended to be exhaustive or exclusive of the present apparatus or method.
Fig. 1 illustrates an embodiment according to the present disclosure.
Fig. 2 illustrates a schematic structure of a wireless headset with active noise reduction according to an embodiment of the present disclosure.
Fig. 3 is a flow chart illustrating a method of noise reduction for a wireless headset with active noise reduction according to an embodiment of the present disclosure.
Detailed Description
In order to better understand the technical solutions of the present disclosure, the following detailed description of the present disclosure is provided with reference to the accompanying drawings and the specific embodiments. Embodiments of the present disclosure will be described in further detail below with reference to the drawings and specific embodiments, but not by way of limitation of the present disclosure. The order in which the steps are described herein by way of example should not be construed as limiting if there is no necessity for a relationship between each other, and it should be understood by those skilled in the art that the steps may be sequentially modified without disrupting the logic of each other so that the overall process is not realized.
Fig. 1 shows a schematic diagram of an active noise reduction process of an earphone 100 according to an embodiment of the present disclosure, as shown in fig. 1, in general, the earphone 100 implements the active noise reduction process through a feed-forward path and a feedback path. To more fully describe the active noise reduction process, the following description is made in connection with the feedforward filter 111, the echo filter 112, and the feedback filter 113; it should be appreciated that the individual filters may be selectively enabled as appropriate (e.g., trade-off between power consumption, time required for noise reduction, and noise reduction effects). Typically the feedforward filter 111 is enabled and the echo filter 112 and the feedback filter 113 may be selectively enabled.
In some embodiments, in the feed-forward path, the external ear microphone 101a collects ambient noise, and the ambient noise collected by the external ear microphone 101a may include an audio component that leaks into the surrounding environment when the speaker 107 of the earphone 100 plays an audio signal, in addition to the noise generated by the surrounding environment, and the portion of the audio component becomes part of the ambient noise. The collected environmental noise is transmitted to the first low-pass and downsampling filter 104a after being subjected to gain processing of the analog gain 102a and analog-to-digital conversion processing of the first analog-to-digital converter 103 a. The first low-pass and downsampling filter 104a can reduce the filter sampling rate, thereby reducing power consumption and filter order, and further reducing the area of the noise reduction chip and reducing cost. Subsequently, the environmental noise signal passing through the first low-pass and down-sampling filter 104a is filtered by the feedforward filter to perform noise reduction processing on the environmental noise collected by the out-of-ear microphone 101 a. The environment signal after the noise reduction processing is transmitted to the adder 109, and then is played by the speaker 107 after the digital-to-analog conversion processing by the digital-to-analog converter 106. The feedforward filtered ambient noise emitted by the speaker 107 and the ambient noise arriving in the ear create an air cancellation to achieve noise reduction.
In some embodiments, in-ear microphone 101b collects in-ear noise on the inside of the earpiece near the ear canal, including audio echo signals generated when the audio signal is played and in-ear residual signals after the air cancellation, in the feedback path. The acquired in-ear noise is transmitted to the second low-pass and down-sampling filter 104b after the gain processing of the analog gain 102b and the analog-to-digital conversion processing of the second analog-to-digital converter 103 b. The second low pass and downsampling filter 104b can reduce the filter sampling rate, thereby reducing power consumption and filter order, and further reducing the area of the noise reduction chip and reducing cost. The in-ear noise signal that has passed through the second low-pass and downsampling filter 104b is then transmitted to the adder 110. The audio signal 105 to be broadcast is an audio signal to be transmitted to the speaker 107 for broadcasting, and on the one hand, it is transmitted to the adder 109, and after digital-to-analog conversion processing by the digital-to-analog converter 106, it is broadcasted by the speaker 107; on the other hand, it is transmitted to an echo filter 112, the echo filter 112 is used to cancel an audio echo signal generated after the audio signal 105 to be broadcast is played through the speaker 107, and then the audio signal 105 to be broadcast filtered by the echo filter 112 is sent to an adder 110. Adder 110 integrates the in-ear noise processed by second low pass and down-sampling filter 104b and the audio signal processed by echo filter 112 such that the noise signal on the feedback path is no longer affected by the audio echo signal. Adder 110 then transmits the integrated noise signal to feedback filter 113 for filtering to achieve feedback noise reduction. The noise signal after feedback filtering is transmitted to the adder 109 after passing through the limiter 108, and is played by the speaker 107 after being subjected to digital-to-analog conversion processing by the digital-to-analog converter 106.
Fig. 2 illustrates a schematic structure of a wireless earphone with active noise reduction function according to an embodiment of the present disclosure, and as shown in fig. 2, the earphone 100 further includes a controller 114 in addition to an in-ear microphone 101b, a speaker 107, and a feedforward filter 111. The speaker 107 is configured to play a cue sound in case the earphone is in the ear or active noise reduction is to be turned on; the in-ear microphone 101b is configured to collect a cue sound in the case where the earphone is in the ear or active noise reduction is to be turned on; the controller 114 is configured to determine relevant parameters of the played alert sound and the collected alert sound and/or to determine an energy parameter of the collected alert sound as a current first parameter in case the earphone is in the ear or an active noise reduction is to be turned on. For example, the energy parameters of the acquired alert tones include the amplitude or power parameters of the acquired alert tones and/or the amplitude or power parameters normalized with respect to the amplitude or power parameters of the played alert tones. The controller 114 is further configured to determine a current filter parameter of the feedforward filter based on the current first parameter and a predetermined correspondence between the first parameter and the filter parameter of the feedforward filter, such that the feedforward filter 111 operates according to the current filter parameter determined by the controller 114. According to the active noise reduction earphone, the current filter parameters of the feedforward filter can be determined rapidly through the prompt tone, so that a user can feel stable noise reduction effect in a short time, and the use experience of the user is improved.
The controller 114 in the present disclosure may be implemented with one or more processors, one or more programmable circuits, one or more dedicated circuits, or a combination thereof. For example, when the controller 114 is implemented as a processor, the processor may be any one or combination of a Micro Processing Unit (MPU), an SOC (system on a chip), and a DSP (digital processing). The programmable circuit is, for example, a Field Programmable Gate Array (FPGA), but is not limited thereto. The dedicated circuit is, for example, an Application Specific Integrated Circuit (ASIC), but is not limited thereto.
The "alert tone" described above in the present disclosure may be "ding", "stings", "ANC ON", "noise reduction open", "in ear", or the like. Meanwhile, the prompt tone often has a richer frequency spectrum, such as 300Hz, 500Hz, 1KHz, 2KHz and the like, and the degree of interference by the outside is light relative to the low-frequency audio signal below 20 Hz. Therefore, the present filter coefficient of the feedforward filter of the earphone is rapidly determined by using the audio signal of the prompt tone in the present disclosure, so that the user can obtain better noise reduction experience in a shorter time, and the satisfaction degree of the user is improved.
In some embodiments, the alert sound may be played by speaker 107 in the event that the headset is in the ear or active noise reduction is to be turned on. In some embodiments, when the active noise reduction function is to be turned on, an alert tone may be played by the speaker 107 before the active noise reduction is turned on. In other embodiments, active noise reduction may be turned on first, where the feedforward filter 111 uses a predetermined or default set of filter coefficients, and then the alert sound is played by the speaker.
In addition, the relevant parameters of the played cue sound and the collected cue sound can be the relevant results of the played cue sound and the collected cue sound. The correlation result may be a cross-correlation processing result of the played alert tone and the collected alert tone, which may be obtained in both the time domain and the frequency domain. The related result may be the result obtained by deconvolution of the played alert sound and the collected alert sound, or by the division or conjugate division of the alert sound played and the collected alert sound in the frequency domain. The correlation result of the played alert tone and the collected alert tone is a representation of the similarity between the played alert tone and the collected alert tone. Specifically, when the correlation results of the played alert sound and the collected alert sound are determined through the cross-correlation process in the time domain, the cross-correlation operation can be performed based on the played alert sound and the collected alert sound, and the result of the cross-correlation operation is a correlation vector. In some embodiments, a partial correlation value may be selected from the correlation vector as a correlation result of the played alert sound and the collected alert sound. In other embodiments, the above-mentioned correlation results may also be normalized by the amplitude or power of the played alert tone and/or the collected alert tone. In the time domain, the present disclosure can obtain the correlation result corr1 (n) by any one of the following formulas (1) - (3).
In the above formula, mic_data is the alert tone collected by the microphone, ref_data is the alert tone played by the speaker, n=0, 1,2, …, N-1, wherein n+1 is the frame length of the audio signal. In other embodiments, n=n0 in the formulas above, where n0 is greater than or equal to 0 and n0< n.
When the correlation result of the played cue tone and the collected cue tone is determined by the cross-correlation processing on the frequency domain, the frequency domain coherence coefficient C of the played cue tone and the collected cue tone signal is calculated first y1y2 (w) taking the frequency domain coherence coefficient as a correlation result of the played cue tone and the collected cue tone, or taking the amplitude or the phase of the frequency domain coherence coefficient as a correlation result of the played cue tone and the collected cue tone. Wherein, the frequency domain coherence coefficient C of the played cue sound and the collected cue sound signals y1y2 (w) can be obtained based on any one of the following formulas (4) to (7):
C y1y2 (ω)＝Φ y1y2 (ω) (5)
wherein C is y1y2 (w) is the frequency domain coherence coefficient, Φ y1y2 (w) is the cross-power spectral density of the played alert tone and the collected alert tone, Φ y1y1 (w) is the power spectral density of the played alert tone, Φ y2y2 (w) is the power spectral density of the collected alert tones, w is the digital angular frequency.
In some embodiments, the first parameter is a corresponding parameter at a plurality of selected frequency points. Specifically, the amplitude or power parameter of the alert tone signal collected by the in-ear microphone may be obtained in either the time domain or the frequency domain. Because the frequency spectrum components of the cue sounds are concentrated near a few frequency points or on a few frequency bands, in order to improve the signal to noise ratio and reduce the influence of external noise, the amplitude or power parameters of the cue sounds collected by the in-ear microphone can be calculated on a few X (X > 1) frequency bands. In some cases, signals of the prompting tones collected by the in-ear microphone on the X frequency bands can be obtained through the X groups of band-pass filters, and then the amplitude or power parameters of the signals on the various frequency bands can be obtained. In other cases, in the frequency domain, signals in X frequency bands are selected, and then the amplitude or power parameters of the signals in each frequency band are obtained. In addition, the amplitude or power parameter of the collected alert sound may also be a vector composed of X amplitude or power parameters. In some embodiments, the amplitude or power parameter of the alert tone signal collected by the in-ear microphone is normalized by the amplitude or power of the alert tone being played, resulting in a normalized amplitude or power parameter. In some embodiments, the amplitude or power parameter of the acquired alert tone may also be a mean or weighted mean of the amplitude or power parameters over multiple frequency bands.
The above-mentioned normalized amplitude or power parameter with respect to the amplitude or power parameter of the played alert tone can be obtained based on the following steps: firstly, acquiring the average value or weighted average value of amplitude or power parameters of the prompt tone acquired by the in-ear microphone on X frequency bands, and then acquiring the average value or weighted average value of the amplitude or power of the played prompt tone on X frequency bands, wherein the normalized result of the former is the amplitude or power parameter normalized relative to the amplitude or power parameter of the played prompt tone. In another case, acquiring first vectors of amplitudes or powers of the alert tones acquired by the in-ear microphone over X frequency bands, the first vectors having X values; obtaining a second vector of the amplitude or the power of the played prompt tone on X frequency bands, wherein the second vector also has X values; the X values of the first vector on the X frequency bands are normalized by the X corresponding values of the second vector, or the first vector is divided by the second vector point, so as to obtain the amplitude or power parameter normalized relative to the amplitude or power parameter of the played alert sound.
In some embodiments, the out-of-ear microphone 101a is configured to collect out-of-ear ambient sounds before the earpiece is in the ear, but before the alert sound is played; and under the condition that the earphone is in the ear or active noise reduction is required to be opened, collecting the external environment sound. The in-ear microphone 101b is further configured to collect in-ear ambient sound before the earphone is in the ear, but before the alert sound is played. The controller 114 is further configured to determine relevant parameters of the in-ear environmental sound and the out-ear environmental sound before the earphone is in the ear, but before playing the alert sound, and to determine the current in-ear environmental sound based on the collected out-ear environmental sound and the relevant parameters of the out-ear environmental sound and the in-ear environmental sound in case the earphone is in the ear or active noise reduction is to be turned on; and finally, removing the current in-ear environment sound from the prompt sound collected by the in-ear microphone for determining the current first parameter.
When the environmental sound of the user is larger, the prompt sound collected by the in-ear microphone is interfered by the environmental sound, and at the moment, the played prompt sound has larger error with the correlation result of the collected prompt sound, so that the proper filter coefficient of the feedforward filter cannot be obtained by utilizing the correlation result. Therefore, the environmental sound is removed from the prompt sound collected by the in-ear microphone in the present disclosure, so that the interference of the environmental sound to the prompt sound is reduced, the influence of the environmental sound on the processing of the prompt sound in the later stage can be reduced, and the noise reduction performance of the earphone is improved. In some embodiments, the parameter associated with the in-ear ambient sound is a transfer function of the acoustic path of the in-ear ambient sound to the in-ear ambient sound, or a ratio or difference in amplitude and/or phase of the in-ear ambient sound to the in-ear ambient sound at a plurality of frequency points. By selecting the ratio or difference of the amplitude and/or the phase of the in-ear environment sound and the in-ear environment sound at a plurality of frequency points, the calculated amount is greatly reduced, and the power consumption of the system is reduced. In some embodiments, the external ear environment sound is obtained by the inverse of the transfer function, and then the current internal ear environment sound is removed from the prompt sound collected by the in-ear microphone to determine the current first parameter. In another embodiment, the current in-ear environment sound may be obtained by calibrating the ratio or the difference between the amplitude and/or the phase of the in-ear environment sound and the in-ear environment sound at a plurality of frequency points, and then the current in-ear environment sound is removed from the alert sound collected by the in-ear microphone to determine the current first parameter.
Further, in some embodiments, the earphone may be first determined to be in an in-ear state, and before the alert sound is played, the external ear microphone 101a is used to collect external ear environmental sound, and determine the magnitude of the environmental sound according to the magnitude, the power parameter, or the magnitude or the power parameter of the external ear environmental sound at a plurality of frequency points in the power set, if the magnitude, the power parameter, or the magnitude or the power parameter of the external ear environmental sound at a plurality of frequency points in the power set is smaller than a predetermined value, it is determined that the environmental sound is smaller, and at this time, the interference of the environmental sound on the alert sound is smaller, and the environmental sound may not be eliminated. In this way, the operation amount of the system is reduced, and in addition, when the environmental sound is smaller, new noise is prevented from being introduced in the process of eliminating the environmental sound, so that the subsequent processing of the prompt sound is influenced. By way of example, the new noise may be circuit noise of an external microphone and a subsequent processing circuit (e.g., ADC, filter circuit) introduced when the environmental sound is eliminated, noise of the elimination process, and the like.
In some embodiments, ambient sounds may also be eliminated using only the in-ear microphone 101 b. Specifically, the earphone is firstly judged to be in an in-ear state, and before the prompt sound is played, the in-ear microphone 101b is used for collecting the environmental sound and detecting whether the prompt sound has stable noise on a plurality of frequency points in the power concentration. If stationary noise exists at certain frequency points, stationary noise can be subtracted from the alert sound collected by the in-ear microphone, so that interference of the ambient sound to the alert sound is reduced, and subsequent processing of the alert sound is less affected by the ambient sound. The detection of whether the stationary noise exists in a certain frequency point can be obtained by judging whether the amplitude or the phase of the environmental sound in the frequency point changes within a preset threshold value in a preset time period before the prompt sound is played.
The correspondence between the predetermined first parameter and the filter parameter of the feedforward filter in the foregoing embodiment includes N sets of preset first parameters and corresponding preset filter parameters of the feedforward filter. Specifically, the correspondence between the predetermined first parameter and the filter parameter of the feedforward filter may be measured in advance in N usage scenarios of the earphone. The usage scenario is defined by any one of or a combination of the ear canal structure, wearing condition and properties of the device on the transmission path of the user or artificial ear. Different ear canal structures, different wearing modes of the earphone and properties (functions, parameters, aging degree and the like) of devices on different transmission paths of the earphone can have certain influence on the noise reduction effect of the earphone, so that different use scenes can be defined by the factors. For example, N groups of different wearing degrees can be selected to obtain N use scenes, and artificial ears or human ears with different sizes can also be selected to obtain N use scenes.
Determining the current filter parameter of the feedforward filter based on the current first parameter and a corresponding relation between the predetermined first parameter and the filter parameter of the feedforward filter specifically comprises selecting a nearest array of preset first parameters from N groups of preset first parameters based on the current first parameter; based on the selected nearest preset first parameters of each group and the respective errors of the current first parameters, the preset filter parameters of the feedforward filter corresponding to the preset first parameters with the minimum errors or errors smaller than the error threshold value can be used as the current filter parameters, and N is a positive integer.
The current filter parameters of the feedforward filter can be rapidly determined through the current first parameters and the corresponding relation between the predetermined first parameters and the filter parameters of the feedforward filter, so that a user can feel stable noise reduction effect in a short time, and the use experience of the user is improved.
In some embodiments, the current first parameter may be a vector, and the corresponding predetermined first parameter may also be a vector. In one case, the sum of absolute values of the results obtained by subtracting the two vectors is used as an error, and the coefficient of the preset feedforward filter corresponding to the set of predetermined first parameters with the smallest error is used as the coefficient of the current feedforward filter. In other cases, the sum of squares of the results obtained by subtracting the two vectors may be used as an error, and the coefficient of the preset feedforward filter corresponding to the set of predetermined first parameters with the smallest error may be used as the coefficient of the current feedforward filter. In other cases, the absolute value of the result obtained by subtracting the two vectors may be weighted and averaged, and then the coefficient of the preset feedforward filter corresponding to the set of predetermined first parameters with the smallest error is used as the coefficient of the current feedforward filter. The sensitivity of the human ear to different frequency points is different, the noise reduction experience and the requirements on the different frequency points are different, the weights of different frequency bands are different, for example, the frequency band has larger noise between the intermediate frequency bands (200 hz-800 hz), the human ear is sensitive to the frequency band, and the human ear is also a larger frequency band for feedforward active noise reduction, so the weight of the frequency band can be increased. The method and the device acquire the coefficients of the current feedforward filter based on the vector of the amplitude or the power parameter formed by a plurality of frequency bands, so that the weight of the sensitive frequency band of the user is improved, and better noise reduction experience can be brought to the user finally.
In some embodiments, if the current first parameter is less than the selected nearest preset first parameter Mdb, the preset filter parameter of the feedforward filter corresponding to the selected nearest preset first parameter is increased by Mdb, where M is a positive number; in the event that the current first parameter is greater than the selected nearest set of preset first parameters Mdb, the preset filter parameters of the feedforward filter corresponding to the selected nearest set of preset first parameters are reduced Mdb by the gain. Illustratively, if the current amplitude or power parameter is 1db less than the selected closest set of preset amplitude or power parameters, the coefficients of the selected feedforward filter are increased by a gain of 1 db. Otherwise, if the current amplitude or power parameter is 2db greater than the selected closest set of preset amplitude or power parameters, the coefficient of the selected feedforward filter is increased by a gain of 2 db. Thus, the noise reduction performance of the earphone is improved.
For feedforward noise reduction, if the gain of the feedforward filter is too large, the noise of the external environment introduced by the feedforward filter is too large, and thus the phenomena such as anti-sound and the like are easy to generate, namely, noise reduction is reduced at certain frequency points (mainly at higher frequency points, such as 1KHz to 3 KHz), even noise can be amplified when serious, and noise reduction experience of a user is affected. Therefore, the present disclosure may further select a preset first parameter closest to the current first parameter from the preset first parameters of each group smaller than the current first parameter; in the case where the current first parameter is greater than the selected preset first parameter Mdb that is closest to the current first parameter, the preset filter parameters of the feedforward filters corresponding to the selected closest preset first parameters of the respective groups are reduced by Mdb by a gain, M being a positive number. For example, if the current amplitude or power parameter or the normalized amplitude or power parameter is between the preset N sets of amplitude or power parameters or the I, J th two sets of normalized amplitude or power parameters, the coefficient of the feedforward filter corresponding to the set with the smaller amplitude or power parameter is selected as the coefficient of the current feedforward filter in the two sets I and J, and the current amplitude or power parameter is 1db larger than the selected set of amplitude or power parameter, the coefficient of the selected feedforward filter is reduced by 1 db. Therefore, the gain is always reduced by adjusting the coefficient gain of the feedforward filter, so that the environmental noise passing through the feedforward filter is not excessive, the possibility of amplifying the noise at a higher frequency point is prevented, and the noise reduction experience of a user is improved.
In some embodiments, the disclosure further provides a noise reduction method of a wireless earphone with an active noise reduction function, as shown in fig. 3, the noise reduction method starts in step S201, where in the case that the earphone is in the ear or active noise reduction is to be turned on, a prompt tone is played by the speaker 107, and the prompt tone is collected by the in-ear microphone 101 b.
In step S202, the controller 114 determines the parameters related to the played alert sound and the collected alert sound, and/or determines the energy parameters of the collected alert sound as the current first parameters; the current filter parameters of the feedforward filter are determined by the controller 114 based on the current first parameter and a predetermined correspondence between the first parameter and the filter parameters of the feedforward filter.
In step S203, the feedforward filter 111 operates according to the determined current filter parameters.
According to the noise reduction method, the current filter parameters of the feedforward filter can be determined rapidly through the prompt tone, so that a user can feel stable noise reduction effect in a short time, and the use experience of the user is improved.
Since the working principle of the noise reduction method of the wireless earphone with the active noise reduction function in the present disclosure is similar to that of the wireless earphone with the active noise reduction function in the foregoing embodiment, the detailed working principle of the noise reduction method of the wireless earphone with the active noise reduction function can be referred to the foregoing embodiment of the wireless earphone with the active noise reduction function, which is not repeated herein.
Furthermore, although illustrative embodiments are described herein, the scope includes any and all embodiments having equivalent elements, modifications, omissions, combinations (e.g., of schemes across various embodiments), adaptations or alterations based on the present disclosure. Elements in the claims will be construed broadly based on the language used in the claims and not limited to examples described in the specification or during the lifetime of the application, which examples are to be construed as non-exclusive. It is intended, therefore, that the description be regarded as examples only, with a true scope being indicated by the following claims and their full range of equivalents.
The above description is intended to be illustrative and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments may be used by those of ordinary skill in the art in view of the above description. Moreover, in the foregoing detailed description, various features may be grouped together to simplify the present disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, the inventive subject matter may lie in less than all features of a single disclosed embodiment. Thus, the claims are hereby incorporated into the detailed description as examples or embodiments, with each claim standing on its own as a separate embodiment, and it is contemplated that these embodiments may be combined with each other in various combinations or permutations. The scope of the application should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.
Claims (15)
1. A wireless earphone with active noise reduction function, which comprises an in-ear microphone, an out-ear microphone, a loudspeaker, a feedforward filter and a controller, and is characterized in that,
the speaker is configured to: playing a prompt tone under the condition that the earphone is in the ear or active noise reduction is required to be opened;
the in-ear microphone is configured to: collecting in-ear environmental sound before the earphone enters the ear but plays the prompt sound; collecting prompt tones under the condition that the earphone is in the ear or active noise reduction is required to be opened;
the extra-aural microphone is configured to: collecting the environmental sound outside the ear before the earphone is in the ear but the prompt sound is played; collecting the external environment sound of the earphone under the condition that the earphone is in the ear or active noise reduction is required to be opened;
the controller is configured to:
before the earphone enters the ear but plays the cue sound, determining relevant parameters of the external environment sound and the internal environment sound, wherein the relevant parameters of the external environment sound and the internal environment sound are transfer functions of acoustic paths from the external environment sound to the internal environment sound or ratios or differences of amplitudes and/or phases of the external environment sound and the internal environment sound at a plurality of frequency points;
in case the earphone is in the ear or active noise reduction is to be turned on,
determining relevant parameters of a played cue sound and a collected cue sound, and/or determining an energy parameter of the collected cue sound as a current first parameter, wherein the collected cue sound is obtained by removing a current in-ear environmental sound from the cue sound collected by the in-ear microphone, and the in-ear environmental sound is determined based on the collected out-ear environmental sound and the relevant parameters of the out-ear environmental sound and the in-ear environmental sound;
the current filter parameters of the feedforward filter are determined based on the current first parameters and a predetermined correspondence between the first parameters and the filter parameters of the feedforward filter.
2. The wireless headset of claim 1, wherein the first parameter is a correlation parameter at a plurality of selected frequency points.
3. The wireless headset of claim 1, wherein the energy parameter of the acquired alert tone comprises an amplitude or power parameter of the acquired alert tone and/or an amplitude or power parameter normalized with respect to an amplitude or power parameter of the played alert tone.
4. The wireless headset of claim 3, wherein the amplitude of the alert tone is a mean or weighted mean of the amplitudes of the alert tones over a plurality of frequency bands, and the power parameter is a mean or weighted mean of the power parameters of the alert tones over a plurality of frequency bands; or alternatively
The amplitude of the prompting sound is a vector formed by the amplitudes of a plurality of prompting sounds, and the power parameter is a vector formed by a plurality of power parameters of the prompting sound.
5. The wireless headset of claim 1, wherein the parameter related to the external and internal ear environment sounds is a transfer function of an acoustic path of the external and internal ear environment sounds, or a ratio or difference in amplitude and/or phase of the external and internal ear environment sounds at a plurality of frequency points.
6. The wireless headset of claim 1, wherein the wireless headset comprises a wireless communication device,
the corresponding relation between the predetermined first parameters and the filter parameters of the feedforward filter comprises N groups of preset first parameters and corresponding preset filter parameters of the feedforward filter;
determining the current filter parameter of the feedforward filter based on the current first parameter and a predetermined correspondence between the first parameter and the filter parameter of the feedforward filter specifically includes: selecting a preset first parameter of the closest array from preset first parameters of N groups based on the current first parameter; the current filter parameters of the feedforward filter are determined based on the respective errors of the selected nearest preset first parameters and the current first parameters, N being a positive integer.
7. The wireless headset of claim 6, wherein the determining the current filter parameters of the feedforward filter based on respective errors of the selected closest sets of preset first parameters and the current first parameters further comprises:
increasing Mdb the preset filter parameters of the feedforward filter corresponding to the preset first parameters of the selected closest groups by a gain of Mdb, M being a positive number, if the current first parameter is smaller than the preset first parameters Mdb of the selected closest groups;
in the event that the current first parameter is greater than the selected nearest set of preset first parameters Mdb, the preset filter parameters of the feedforward filter corresponding to the selected nearest set of preset first parameters are reduced Mdb by the gain.
8. The wireless headset of claim 6, wherein the determining the current filter parameters of the feedforward filter based on respective errors of the selected closest sets of preset first parameters and the current first parameters further comprises:
further selecting a preset first parameter closest to the current first parameter from all preset first parameters smaller than the current first parameter;
in the case where the current first parameter is greater than the selected preset first parameter Mdb that is closest to the current first parameter, the preset filter parameters of the feedforward filters corresponding to the selected closest preset first parameters of the respective groups are reduced by Mdb by a gain, M being a positive number.
9. A noise reduction method of a wireless earphone with an active noise reduction function, the wireless earphone including an in-ear microphone, an out-of-ear microphone, a speaker, a feedforward filter, and a controller, the noise reduction method comprising:
before the earphone enters the ear, but before the prompt sound is played, the in-ear microphone collects in-ear environment sound, the out-of-ear microphone collects out-of-ear environment sound, and relevant parameters of the out-of-ear environment sound and the in-ear environment sound are determined, wherein the relevant parameters of the out-of-ear environment sound and the in-ear environment sound are transfer functions of acoustic paths from the out-of-ear environment sound to the in-ear environment sound, or the ratio or difference of the amplitude and/or the phase of the out-of-ear environment sound and the in-ear environment sound at a plurality of frequency points;
in case the earphone is in the ear or active noise reduction is to be turned on,
the method comprises the steps that a loudspeaker plays prompt tones, an in-ear microphone collects the prompt tones, and an out-ear microphone collects out-of-ear environmental tones;
determining, by a controller, relevant parameters of a played alert sound and an acquired alert sound, and/or determining an energy parameter of the acquired alert sound as a current first parameter, the acquired alert sound being obtained by removing a current in-ear environmental sound from the alert sound acquired by the in-ear microphone, wherein the in-ear environmental sound is determined based on the acquired out-ear environmental sound and the relevant parameters of the out-of-ear environmental sound and the in-ear environmental sound; determining, by a controller, a current filter parameter of the feedforward filter based on the current first parameter and a predetermined correspondence between the first parameter and a filter parameter of the feedforward filter; and
the feedforward filter operates according to the determined current filter parameters.
10. The noise reduction method of claim 9, wherein the first parameter is a correlation parameter at a plurality of selected frequency points.
11. The method of noise reduction according to claim 9, wherein the energy parameters of the acquired alert tones include the amplitude or power parameters of the acquired alert tones and/or the amplitude or power parameters normalized with respect to the amplitude or power parameters of the played alert tones.
12. The method of claim 11, wherein the amplitude of the alert tone is a mean or weighted mean of the amplitudes of the alert tones in a plurality of frequency bands, and the power parameter is a mean or weighted mean of the power parameters of the alert tones in a plurality of frequency bands; or alternatively
The amplitude of the prompting sound is a vector formed by the amplitudes of a plurality of prompting sounds, and the power parameter is a vector formed by a plurality of power parameters of the prompting sound.
13. The noise reduction method according to claim 9, wherein the correspondence between the predetermined first parameters and the filter parameters of the feedforward filter includes N sets of preset first parameters and corresponding preset filter parameters of the feedforward filter;
determining the current filter parameter of the feedforward filter based on the current first parameter and a predetermined correspondence between the first parameter and the filter parameter of the feedforward filter specifically includes: selecting a preset first parameter of the closest array from preset first parameters of N groups based on the current first parameter; the current filter parameters of the feedforward filter are determined based on the respective errors of the selected nearest preset first parameters and the current first parameters, N being a positive integer.
14. The noise reduction method of claim 13, wherein said determining current filter parameters of said feedforward filter based on respective errors of said selected closest respective sets of preset first parameters and said current first parameters further comprises:
increasing Mdb the preset filter parameters of the feedforward filter corresponding to the preset first parameters of the selected closest groups by a gain of Mdb, M being a positive number, if the current first parameter is smaller than the preset first parameters Mdb of the selected closest groups;
in the event that the current first parameter is greater than the selected nearest set of preset first parameters Mdb, the preset filter parameters of the feedforward filter corresponding to the selected nearest set of preset first parameters are reduced Mdb by the gain.
15. The noise reduction method of claim 13, wherein said determining current filter parameters of said feedforward filter based on respective errors of said selected closest respective sets of preset first parameters and said current first parameters further comprises:
further selecting a preset first parameter closest to the current first parameter from all preset first parameters smaller than the current first parameter;
in the case where the current first parameter is greater than the selected preset first parameter Mdb that is closest to the current first parameter, the preset filter parameters of the feedforward filters corresponding to the selected closest preset first parameters of the respective groups are reduced by Mdb by a gain, M being a positive number.
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