CN117528377A - Method for calibrating a removable audio device, and associated system and computer program product for calibrating a removable audio device - Google Patents
Method for calibrating a removable audio device, and associated system and computer program product for calibrating a removable audio device Download PDFInfo
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- CN117528377A CN117528377A CN202310936874.7A CN202310936874A CN117528377A CN 117528377 A CN117528377 A CN 117528377A CN 202310936874 A CN202310936874 A CN 202310936874A CN 117528377 A CN117528377 A CN 117528377A
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- 238000004590 computer program Methods 0.000 title claims description 10
- 230000005236 sound signal Effects 0.000 claims abstract description 43
- 238000004364 calculation method Methods 0.000 claims description 4
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- 238000004422 calculation algorithm Methods 0.000 description 4
- 230000006399 behavior Effects 0.000 description 3
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- 238000005457 optimization Methods 0.000 description 3
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Classifications
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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
- H04R29/00—Monitoring arrangements; Testing arrangements
- H04R29/001—Monitoring arrangements; Testing arrangements for loudspeakers
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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
- H04R29/00—Monitoring arrangements; Testing arrangements
- H04R29/004—Monitoring arrangements; Testing arrangements for microphones
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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
- H04R2460/00—Details of hearing devices, i.e. of ear- or headphones covered by H04R1/10 or H04R5/033 but not provided for in any of their subgroups, or of hearing aids covered by H04R25/00 but not provided for in any of its subgroups
- H04R2460/01—Hearing devices using active noise cancellation
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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
- H04R5/00—Stereophonic arrangements
- H04R5/033—Headphones for stereophonic communication
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- General Health & Medical Sciences (AREA)
- Otolaryngology (AREA)
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Circuit For Audible Band Transducer (AREA)
- Soundproofing, Sound Blocking, And Sound Damping (AREA)
Abstract
The present invention relates to a method of calibrating a removable audio device 10, the removable audio device 10 comprising at least one removable microphone 20, 25 and a removable speaker 15, the removable audio device 10 being arranged in a box 95 comprising a calibration system 75. The calibration system comprises a calibration microphone 80, a calibration speaker 85 and an electronic calibration device 90. The method comprises the following steps: -an emission phase emitting an audio signal to a movable speaker or a calibration speaker to emit said audio signal, -the calibration phase comprising: -receiving a signal obtained by capturing an audio signal emitted by the movable microphone or the calibration microphone, -determining a calibration filter h_calib_spk based on the received signal; h_calilb_fb; h_calib_ff, -an implementation stage, implementing the determined calibration filter in the removable audio device.
Description
[ field of technology ]
The invention relates to a calibration method of a mobile audio device.
The invention further relates to a calibration system and a computer program product for calibrating a removable audio system.
The present invention relates to the field of the manufacture of removable audio devices.
The term "removable audio device (dispositif audio nomade)" is understood to mean a device configured to deliver audio content from an audio source to a device user, which device is transportable with the audio source. The audio source is for example an MP3 walkman or a smart phone. The removable audio device is an in-ear device, also known as a headset. As a variant, the removable audio device is for example an out-of-the-ear device, also called a headset.
[ background Art ]
In a manner known per se, the movable audio means comprise at least one movable speaker, and preferably one inner movable microphone and at least one outer movable microphone for each movable speaker.
The movable speaker is configured to emit sound content from the source.
In a manner known per se, the internal movable microphone is directed towards the movable speaker and is intended to be located between said movable speaker and the user's ear. The movable microphone is configured to collect audio signals broadcast by the movable speaker.
An external movable microphone is disposed at the periphery of the movable audio device and faces the outside of the device. The external movable microphone is configured to collect an audio stream surrounding the movable audio device, such as a user's utterance.
In a manner known per se, the movable speaker, the external movable microphone and the movable speaker together enable a telephone function to be achieved by the mobile telephone headset. In such a function, the user's utterance is picked up by an external movable microphone and the utterance of a third party in communication with the user is played by a movable speaker.
Furthermore, in a manner known per se, the movable speaker, the internal movable microphone and the external movable microphone enable an active noise reduction function to be implemented for noise around the movable audio device.
According to this function, ambient noise is collected by the external movable microphone. The noise is processed by a filter and signals a movable speaker to cancel ambient noise that passed through the audio device. Furthermore, the internal movable microphone enables to minimize noise remaining in the vicinity of the user's eardrum by corresponding filter control. Feedback is performed on the movable speaker based on signals acquired by the internal movable microphone.
It is thus apparent that the inner and outer microphones and the speaker are connected to each other. The transfer function between these elements can thus be calculated.
In a manner known per se, each of the movable speaker and the movable microphone has its own frequency response.
Speakers and microphones are typically mass-produced components. Thus, it is known to determine for each model its respective nominal frequency response and the maximum dispersion between the frequency response of a particular component and the nominal response associated with that component's model.
Traditionally, the maximum dispersion is equal to, for example, ±3dB.
In an industrial context, it is often desirable to design each filter of a removable audio device according to the nominal frequency response of each component without taking into account the dispersion between the behavior of the component in the headset and its nominal behavior in practice. Furthermore, the design of each filter typically does not account for imperfections during assembly of the components to form the removable audio device.
However, when the frequency response of components in an audio device differs significantly from the nominal frequency response or when the device has assembly defects, the filter is not necessarily still suitable for the obtained device.
The user experience is then at least degraded. In the worst case, these defects may cause the closed loop transfer function to be unstable, resulting in a howling phenomenon, which is particularly uncomfortable for the user.
The present invention proposes a calibration method, a computer program product and a related calibration system of a removable audio device enabling such problems to be avoided.
[ invention ]
To this end, the subject of the invention is a method of calibrating a removable audio device, such as a headset or a pair of headphones, comprising at least one removable microphone and a removable loudspeaker, the removable audio device being arranged in a box (caisson) comprising a calibration system,
the calibration system comprises a calibration microphone, a calibration speaker and an electronic calibration device connectable to the calibration microphone and the calibration speaker, the method being implemented by the electronic calibration device and comprising:
at least one emission phase during which an audio signal is sent to one of the movable speaker and the calibration speaker, the audio signal being emitted by said speaker,
-a calibration phase during which at least one of the at least one movable microphone and the movable speaker is calibrated, the calibration phase comprising:
receiving a signal resulting from the acquisition of the emitted audio signal by the microphone from one of at least one movable microphone and a calibration microphone,
determining a calibration filter based on the signal received during reception, the calibration filter being a digital filter having a gain, the value of the gain varying with frequency,
calibrating the filter:
or is specific to the at least one movable microphone and is configured to filter any signals acquired by said movable microphone,
or is specific to a movable speaker and is configured to filter any signal intended to be emitted by said movable speaker,
-an implementation phase of implementing the calibration filter determined during the calibration phase in the removable audio device.
By determining the calibration filter and its implementation in the removable audio device, the performance of the device is improved according to the performance of the removable speaker and the removable microphone actually present in the removable audio device, rather than merely based on the nominal performance of the model of these components.
According to a particular embodiment of the invention, the calibration method according to the invention further comprises one or more of the following features considered alone or following any technically possible combination:
the emission phase comprises a step of emission by a movable speaker, during which an audio signal is sent to the movable speaker to be emitted by said movable speaker,
the calibration phase comprises the step of calibrating the movable speaker,
during the receiving of the calibration step, an audio signal is received from a calibration microphone,
during the determination of the calibration step, the determined calibration filter is specific to the movable speaker, and is referred to as a speaker calibration filter,
the movable audio device comprises two movable microphones comprising an inner movable microphone towards the movable speaker and an outer movable microphone towards the outside of the movable audio device,
the calibration phase further comprises the step of calibrating the internal movable microphone,
during the receiving of the step of calibrating the internal movable microphone, an audio signal is received from the internal movable microphone,
during the determination of the step of calibrating the internal movable microphone, the determined calibration filter is specific to the internal movable microphone, and is referred to as an internal microphone calibration filter,
the step of calibrating the internal movable microphone further comprises:
applying a speaker calibration filter to signals received during reception of the step of calibrating the internal movable microphone to form filtered signals,
during the step of determining the stage of calibrating the internal movable microphone, an internal microphone calibration filter is determined from the filtered signal,
the emission phase comprises the step of emitting by a calibration loudspeaker, during which an audio signal is sent to the calibration loudspeaker to be emitted by said calibration loudspeaker,
the calibration phase comprises the step of calibrating the external movable microphone,
during the receiving of the step of calibrating the external movable microphone, an audio signal is received from the external movable microphone,
during the determination of the step of calibrating the external movable microphone, the determined calibration filter is specific to the external movable microphone, and is referred to as an external microphone calibration filter,
the removable audio device further comprises a control unit comprising an adder, a first connection connecting the adder to the removable speaker, a second connection connecting the internal removable microphone to the adder, and a third connection connecting the external removable microphone to the adder,
the removable audio device further comprises a first predetermined filter on the second connection and a second predetermined filter on the third connection,
during the implementation phase, at least one of the calibration filter or the calibration filter is implemented on one of the first connection, the second connection and the third connection,
the or each determining sub-step comprises:
calculating a frequency error between the respective received signal and a predetermined reference signal,
detecting the extreme value(s) of the frequency error,
-for at least one detected extremum:
-calculating the frequency band around the extremum,
-determining a parametrizable element filter (filtre unitaire param) based on the frequency error in the frequency band,
generating a calibration filter based on the or each parametrizable unit filter,
each parametrizable element filter preferably comprises the following adjustable parameters: center frequency, maximum gain and quality factor,
preferably, each parametrizable unit filter further comprises a filter type selected from the group consisting of: a peak or valley filter, a graded low-pass filter and a graded high-pass filter,
for each detected extremum, during the calculation of the frequency bands, each frequency band is delimited by a lower limit and an upper limit,
the lower limit of the frequency band is the upper limit of the previous frequency band,
the upper limit of the band is calculated according to the following equation:
wherein the method comprises the steps of
-Is in the frequency band B i Is a frequency of the detected extremum in (c),
-is the frequency of the detected extremum in the next frequency band,
-
-is the norm of the error estimated at the frequency of the detected extremum in the frequency band, and
-is the norm of the error estimated at the frequency of the detected extremum in the next frequency band; and is also provided with
The movable audio means comprises at least two audio channels, each audio channel comprising at least one respective movable microphone and a respective movable speaker,
the steps of the calibration method are iterated for each audio channel.
The subject matter of the present invention is also a computer program product comprising software instructions which, when executed by a computer, implement the calibration method as described above.
The subject of the invention is also a calibration system for a removable audio device, such as a headset or a pair of headphones, comprising at least one removable microphone, a removable speaker, the removable audio device being placeable in the calibration system,
the calibration system comprises a calibration microphone, a calibration speaker and electronic calibration means executable software instructions of the computer program product.
[ description of the drawings ]
The invention will be better understood and its advantages will emerge from reading the following description, which is given purely by way of non-limiting example and with reference to the accompanying drawings, in which:
fig. 1 is a schematic diagram of a removable audio device before applying the calibration method according to the invention;
fig. 2 is a schematic diagram of the removable audio device of fig. 1 during implementation of the calibration method according to the invention; and is also provided with
Fig. 3 is a flow chart of a calibration method according to the invention.
[ detailed description ] of the invention
A removable audio device 10 is shown in fig. 1.
In the example of fig. 1, the removable audio device 10 is a pair of headphones. In a variant not shown, the removable audio device is a headset.
The removable audio device 10 optionally includes a first audio channel CH1 and a second channel CH2.
For example, the first audio channel CH1 is the left-hand channel, i.e. intended to broadcast content to the user's left ear. In this example, the second channel CH2 is a right side channel, i.e., intended to broadcast content to the user's right ear.
Obviously, the opposite configuration is also possible.
The movable audio set 10 comprises one movable speaker 15 and at least one movable microphone 20, 25 for each audio channel CH1, CH2.
In addition, the removable audio device 10 preferably comprises for each audio channel CH1, CH2 a connection point 30 with an audio source (not shown) and a control unit 33.
The removable speaker 15 is configured to broadcast content from an audio source. Optionally, the movable speaker 15 is configured to broadcast content determined by the control unit 33, for example, in order to implement an active noise reduction function.
The movable microphones 20, 25 are configured to collect audio signals. Preferably, the removable audio device 10 advantageously comprises an inner removable microphone 20 and at least one outer removable microphone 25 for each channel CH1, CH2.
The internal movable microphone 20, also referred to as internal microphone 20, is configured to collect audio signals between the movable speaker 15 and the user's ear, in particular audio signals broadcast by the movable speaker 15. It will then be appreciated that the internal movable microphone 20 is disposed between the movable speaker 15 and the eardrum of the user when the audio device is worn by the user. The internal movable microphone 20 is then configured to pick up the audio signal heard by the user.
The external movable microphone 25, also referred to as external microphone 25, is configured to collect audio streams surrounding the movable audio device 10. To this end, an external microphone 25 is provided at the periphery of the movable audio device 10 and directed towards the outside of said device 10.
The connection point 30 is configured to receive content from an audio source to be broadcast by the removable speaker 15. The connection point 30 is for example configured to communicate with the audio source via a wired connection or, as shown in fig. 1, via a wireless connection according to a predefined protocol, such as the bluetooth or WIFI protocol.
The control unit 33 is configured to control the signal sent to the movable speaker 15 in dependence of the signal received from the connection point 30, the signal picked up by the internal microphone 20 and the signal picked up by the external microphone 25.
The control unit 33 is connected to the movable speaker 15, the inner microphone 20, the outer microphone 25 and the connection point 30. The control unit 33 is, for example, an electronic circuit board including a plurality of software modules.
The control unit 33 comprises an adder 35, a first connection 50 connecting the adder 35 and the movable speaker 15, a second connection 55 connecting the inner microphone 20 and the adder 35, a third connection 60 connecting the outer microphone 25 and the adder 35, and a fourth connection 65 preferably connecting the connection point 30 to the adder 35.
The control unit 33 comprises for example a conversion and amplification block 70 on the first connection 50. Block 70 is formed, for example, by a DAC converter (digital-to-analog converter) which converts the digital signal from adder 35 into an analog signal for exciting movable speaker 15, and an analog signal amplifier.
The control unit 33 preferably further comprises a first predetermined filter HFB on the second connection 55. The first predetermined filter HFB is configured to filter the signal acquired from the internal movable microphone 20 and then send it to the adder 35.
The control unit 33 preferably further comprises a second predetermined filter HFF on the third connection 60. The second predetermined filter HFF is configured to filter the signal acquired from the external movable microphone 25 and then transmit it to the adder 35.
The first predetermined filter HFB and the second predetermined filter HFF are for example designed according to the nominal frequency response of the inner microphone 20 and the outer microphone 25, as provided by the manufacturer of said microphones and measured on a reference prototype.
The control unit 33 further comprises an equalizer HEQ on a fourth connection 65. The equalizer HEQ is configured to perform equalization on the signal from the connection point 30 and then transmit it to the adder 35.
In fig. 2, the removable audio device 10 is coupled with a calibration system 75 to calibrate the audio device 10. In fig. 2, only one channel CH1, CH2 of the removable audio device 10 is shown.
Calibration system 75 includes a calibration microphone 80, a calibration speaker 85, and an electronic calibration device 90 connectable to calibration microphone 80 and calibration speaker 85.
To calibrate the mobile audio device 10, the device 10, calibration microphone 80 and calibration speaker 85 are placed in an acoustically sealed box 95. The calibration microphone 85 is located adjacent to the inner movable microphone 20, for example within an artificial ear (not shown). And the calibration speaker 85 is located outside the mobile audio device 10.
The calibration microphone 80 and the calibration speaker 85 are connected to an electronic calibration device 90, as shown in solid lines in fig. 2.
The movable speaker 15, the internal microphone 20 and the external microphone 25 are connected to an electronic calibration device 90, as indicated by the dashed lines in fig. 2.
The electronic calibration device 90 is located outside the box 95. The electronic calibration device 90 is, for example, a computer including a memory 96 and a processor 97 that can execute software instructions stored in the memory 96.
The memory 96 stores a computer program comprising software instructions that when executed by the processor 97 implement a calibration method of calibrating the removable audio device 10 as described below.
Referring to fig. 3, the calibration method of the mobile audio device 10 includes an emission phase during which an audio signal is sent to one of the mobile speaker 15 and the calibration speaker 85.
The emission phase preferably first comprises a first emission step pe_nomide during which the calibration means 90 send an audio signal, called first audio signal, to the movable speaker 15. After this first emitting step PE, the movable speaker 15 emits a first audio signal to the internal movable microphone 20 and the calibration microphone 80. The first audio signal is for example a continuous sinusoidal sweep. During the emission of the first audio signal by the movable speaker 15, the calibration microphone 80 and the internal movable microphone 20 collect the emitted signals.
The calibration method then comprises a calibration phase of calibrating at least one of the movable speaker 15, the inner movable microphone 20 and the outer movable microphone 25.
The calibration phase preferably comprises a step pc_spk of calibrating the movable speaker 15.
The calibration step pc_spk comprises a first receiving sub-step 112 during which the electronic calibration device 90 receives from the calibration microphone 80 a signal resulting from said microphone picking up a first audio signal emitted by the movable speaker 15.
The calibration step pc_spk further comprises a first determination sub-step 114 during which the calibration means 90 determine a first calibration filter h_calib_spk based on the signal received from the calibration microphone 80. The first calibration filter h_calib_spk is a digital filter with a gain whose value varies with frequency. By "the value of the gain varies with frequency (un gain dont une valeur e volume fr volume)" it is meant that the gain assumes different values depending on the frequency of the signal supplied to the correlation filter. The first calibration filter h_calib_spk is specific to the movable speaker 15.
To this end, the first determination sub-step 114 advantageously comprises calculating a frequency error Err (f) between the signal received during the first reception sub-step 112 and the first predetermined reference signal.
If the frequency response of the movable speaker 15 happens to be the nominal frequency response of the reference product, the first reference signal corresponds to the signal that the calibration microphone 80 would have acquired.
To calculate this error Err (f), in the following example, the calibration device 90 calculates the fourier transform of the signal received from the calibration microphone 80. In a manner known per se, the signal resulting from the fourier transformation comprises an amplitude and a phase which vary with frequency, respectively.
Still during the calculation of the frequency error Err (f), the calibration means 90 subtract, for example, the fourier transformed amplitude from the amplitude of the first predetermined reference signal, for example, according to the following equation:
[ math 1 ]
Err(f)＝dB(Target(f))-dB(Init(f))
Where Target (f) is a first predetermined reference signal,
init (f) is the fourier transform of the received signal, and
dB (deg.) is the operation that converts amplitude into decibels.
Then, still during the determination sub-step 114, the calibration means 90 advantageously detect the extremum(s) in the frequency error Err (f)
For this purpose, the calibration device 90 calculates the frequency derivative of the frequency error Err (f), for example, and determines each frequency of the derivative bits zero
Still during the determining substep 114, the calibration means 90 preferably for each determined extremumTo calculate the extremum->The surrounding frequency band Bi. Two consecutive bands B i-1 、B i Are connected to each other. In other words, each frequency band B i Including a lower limit f 1 i And an upper limit f 2 i . And, band B i Lower limit f of (2) 1 i Is the previous frequency band B i-1 Upper limit f of (2) 2 i 。
First frequency band B 1 Lower limit f of (2) 1 1 Is the minimum frequency defining the frequency error Err (f). Then, band B is calculated according to the following equation i Upper limit f of (2) 2 i ：
[ formula 2 ]
Wherein the method comprises the steps of
In band B i At the end of the calculation of (a), the entire frequency domain defining the frequency error Err (f) is divided into a plurality of frequency bands B i . Each frequency band B i An extremum comprising the frequency error Err (f)
Still during the determination substep 114, the calibration means 90, for example for each extremumDetermining a parametrizable element filter H i Which is +.>Associated band B i Is a function of the frequency error Err (f).
Each parametrizable unit filter H i For example a peak or Gu Lvbo device known per se (english "peak-notch", peak notch). The filter H i Characterized by three parameters: center frequency f c i Gain A i And quality factor Q i . In a manner known per se, the center frequency f c i Corresponding to parametrizable unit filter H i The frequency with the highest gain. Gain A i Corresponding to the maximum gain of the parametrizable element filter, e.g. gain f at the center frequency for a peak notch filter c i . Quality factor Q i The passband size of the parametrizable element filter is quantized.
The calibration means 90 then advantageously initialize the parametrizable unit filter H i And calculates, for example, band B according to the following equation i Is a modified frequency error of (a):
[ formula 3 ]
Err(f)＝dB(Target(f))-dB(H i (f)*Init(f))
Wherein f is f 1 i And (3) withBetween them.
If the received signal is obtained by a parametrizable unit filter H i Filtered, the previous equation corresponds to the frequency error.
The calibration means 90 then optionally apply an optimization algorithm to the parameters of the parametrizable unit filter in order to minimize the error defined based on the corrected error from a least squares point of view, and it is written, for example, as follows:
[ math figure 4 ]
Where N is at frequency f 1 i And f 2 i The number of samples of the signal received therebetween.
The optimization algorithm is, for example, a gradient descent algorithm.
After application of the optimization algorithm, the calibration means 90 obtain a parametrizable unit filter H i Optimized parameters of (a)And->
Advantageously, the calibration means 90 are such that for each extremumThus, for each relevant frequency band Bi, a corresponding parametrizable element filter H is determined i 。
Next, the calibration means 90 are based on, for example, each parametrizable unit filter H determined previously i Generating a first calibration filter H_calib_SPK, for example, by combining each parametrizable element filter H i Arranged in series.
The calibration phase optionally further comprises a step pc_fb of calibrating the internal movable microphone 20.
As previously described, after the movable speaker 15 emits the first audio signal, the internal movable microphone 20 collects the emitted first audio signal.
The step pc_fb of calibrating the internal movable microphone 20 comprises a second receiving sub-step 122 during which the calibration means 90 receives the first audio signal acquired by the internal microphone 20.
Preferably, the step pc_fb of calibrating the internal microphone 20 comprises an application sub-step 123 of applying a first calibration filter h_calib_spk to the signal received from the internal microphone 20 to form a filtered signal.
Step pc_calib_fb comprises a second determination substep 124 during which the calibration means 90 determine a second calibration filter h_calib_fb based on the filtered signal. The second calibration filter h_calib_fb is also a digital filter having a gain whose value varies with frequency. The second calibration filter h_calib_fb is specific to the internal movable microphone 20.
The second determination sub-step 124 is similar to the first determination sub-step 114, except that the determination is made based on the signal received by the internal movable microphone 20 filtered by the function h_calib_spk, rather than based on the signal received from the calibration microphone 80.
At the end of the second determination substep 124, a second calibration filter h_calib_fb is determined.
The send-out phase then comprises a send step pe_calib, sending the second audio stream to be broadcast by the calibration speaker 85. After this transmitting step pe_calib, the calibration speaker 85 emits a second audio signal. During this emission, the emitted second audio signal is picked up by the external movable microphone 25.
Similar to the first audio signal, the second audio signal is, for example, a continuous sinusoidal sweep.
The calibration phase then comprises, for example, a step pc_ff of calibrating the external movable microphone 25.
The step pc_ff of calibrating the external movable microphone 25 comprises a third receiving sub-step 132 during which the calibration means 90 receives the signal picked up by the external movable microphone 25 after the calibration speaker 85 emits the second audio signal.
The step pc_ff of calibrating the external movable microphone 25 further comprises a third determination sub-step 134 during which a third calibration filter h_calib_ff is determined based on the signal received from the external movable microphone 25. The third calibration filter h_calib_ff is also a digital filter with a gain whose value varies with frequency. The third calibration filter h_calib_ff is specific to the external movable microphone 25.
The third determination sub-step 134 is for example similar to the first determination sub-step 114 and the second determination sub-step 124, except that the third calibration filter h_calib_ff is determined based on the signal received from the external movable microphone 25 and not based on the signal received from the calibration microphone 80 or from the internal movable microphone 20.
At the end of the determination sub-step 134, a third calibration filter H_calib_FF is determined.
The calibration method further comprises an implementation phase PI, which preferably comprises a first implementation step 142 during which a first calibration filter h_calib_spk is implemented in the removable audio device 10, more precisely on the first connection 50 of the control unit 33. For example, a first calibration filter h_calib_spk is implemented between adder 35 and block 70.
The implementation phase PI also preferably comprises a second implementation step 144 during which a second calibration filter h_calib_fb is implemented in the removable audio device 10 and more specifically on the second connection 55 of the control unit 33. For example, the second calibration filter h_calib_fb is implemented between the internal movable microphone 20 and the first predetermined filter HFB.
The implementation phase PI also preferably comprises a third implementation step during which a third calibration filter h_calib_ff is implemented in the removable audio device 10 and preferably on the third connection 60 of the control unit 33. For example, a third calibration filter h_calib_ff is implemented between the external movable microphone 25 and the second predetermined filter HFF.
At the end of the calibration method according to the invention, the movable speaker 15, the inner movable microphone 20 and the outer movable microphone 25 are calibrated.
At the end of the implementation phase PI, the value of the or each calibration filter h_calib_spk, h_calib_fb, h_calib_ff is stored in the control unit 33 and preferably in the memory 96 of the control unit.
When the removable audio device 10 includes a plurality of audio channels CH1, CH2, the above calibration method is repeated for each audio channel CH1, CH2.
According to a first variant, the step pe_calib of transmitting the second audio signal and the step pc_ff of calibrating the external movable microphone 25 are performed before the step pe_nomide of transmitting the first audio signal.
According to a second variant, not shown, the audio device 10, preferably each audio channel CH1, CH2, comprises a plurality of externally movable microphones 25 i . According to this second variant, the control unit 33 comprises a connection to the external movable microphones 25, respectively i And a plurality of third connections 60 to adder 35 i . The control unit 33 is connected to these connections 60 i Including a respective second predetermined filter HFF thereon i 。
According to this second variant, after the step pe_calib of transmitting the second audio signal to the calibrated speaker 85, each external movable microphone 25 i A second audio signal from the emission is collected. Then, for each external movable microphone 25, the calibration phase comprises a step pc_ff of calibrating said external movable microphone 25 i During this time, the external movable microphone 25 is determined i Is defined by the respective third filter H_calib_FF i 。
According to the second modification, for each external movable microphone 25 i The implementation phase includes a corresponding third implementation step 146 i During this time, in communication with the external movable microphone 25 i Associated connection 60 i On which a corresponding third calibration filter H_calibr_FF is implemented i 。
According to a third variant, which can be combined with one of the other variants, for example, each parametrizable unit filter H i Is a graded low pass filter (lowshell, low filter in english) or a graded high pass filter (highshell, high filter in english). Parametrizable element filter H i The parameters of (2) are the same as in the case of the peak notch filter.
In a manner known per se, the low-pass filter or the high-pass filter defines a slope that decreases or increases, respectively. Each parametrizable unit filter H in the form of a low-pass filter or a high-pass filter i From the central frequency f c i Gain A i And quality factor Q i To parameterize. In a manner known per seMode, center frequency f c i Corresponding to a frequency intermediate the slopes of the low-pass filter or the high-pass filter. Gain A i Corresponding to the maximum gain of the parametrizable element filter. Quality factor Q i The slope overstable (raieur) of the low-pass filter or the high-pass filter type filter is quantized.
According to a fourth variant, during each determination sub-step 114, 124, 134, frequency pre-partitioning is performed in a predefined manner forming a plurality of frequency parts. A frequency portion having a width greater than a frequency band B i Is a width of (c). Parametrizable element filter H for each frequency portion i Is predefined. In determining frequency band B i During which the frequency band B is determined i Up to band B in a frequency part i Up to the number of parametrizable unit filters H of the section i Maximum number of (a).
According to a fifth variant, only one of the movable speaker 15, the internal microphone 20 and the external microphone 25 is calibrated. In this case, the issue phase includes only one issue step pe_node, pe_calib. In this case, the calibration phase comprises only one calibration step pc_spk, pc_fb, pc_ff. In this way, the individual calibration filters h_calib_spk, h_calib_fb, h_calib_ff are determined and implemented in the removable audio device 10.
Obviously, the method may also include one or two of the three calibrations described above.
The method according to the invention thus makes it possible to avoid problems associated with variations in the frequency response of the components of the audio device relative to the nominal frequency response. In fact, after applying the method, the behaviour of each calibrated component is close to the nominal frequency response provided by the manufacturer for the model of the component.
In addition, determining the calibration filter(s) specific to each of the movable speaker 15, the internal movable microphone 20, and the external movable microphone 25 in the movable audio apparatus 10 enables customizing the corrections made and thus further improves the user experience.
In addition, the method according to the invention can be implemented by a computer program product without any human intervention. Thus, the method is fast and efficient.
In the preferred mode, the step pc_fb of calibrating the internal microphone 20 is free from errors exhibited by the movable speaker 15 before its calibration, due to the application of the substep 123. In practice, the application step 123 has the effect that the signal acquired by the internal microphone 20 is emitted by the calibrated movable speaker 15. This step speeds up the calibration method, as it enables calibration of both the movable speaker 15 and the internal microphone 20, with only one emission performed by the movable speaker 15.
Claims (14)
1. A method of calibrating a removable audio device (10), such as a headset or a pair of headphones, the removable audio device (10) comprising at least one removable microphone (20, 25) and a removable speaker (15), the removable audio device (10) being arranged in a box (95) comprising a calibration system (75), the calibration system (75) comprising a calibration microphone (80), a calibration speaker (85) and an electronic calibration device (90) connectable to the calibration microphone (80) and the calibration speaker (85), the method being implemented by the electronic calibration device (90) and comprising:
at least one emission phase during which an audio signal is sent to one of the movable speaker (15) and the calibration speaker (85), the audio signal being emitted by said speaker (15; 85),
-a calibration phase during which at least one of the at least one movable microphone (20, 25) and the movable speaker (15) is calibrated, the calibration phase comprising:
receiving (112; 122; 132) from one of at least one movable microphone (20, 25) and a calibration microphone (80) a signal resulting from the acquisition of the emitted audio signal by said microphone (20, 25; 80),
-determining (114; 124) based on signals received during reception (112; 122; 132);
134 -calibrating the filter (h_calib_spk; h_calilb_fb; h_calib_ff), a calibration filter (h_calib_spk; h_calilb_fb; h _ calib _ FF) is a digital filter with gain,
the value of the gain varies with frequency,
calibration filter (h_calib_spk; h_calib_fb; h_calib_ff):
either specific to the at least one movable microphone (20, 25) and configured to filter any signals acquired by said movable microphone (20, 25),
either specific to the movable speaker (15) and configured to filter any signals intended to be emitted by said movable speaker (15),
-an implementation Phase (PI) of implementing in the removable audio device (10) the calibration filter (h_calib_spk; h_calilb_fb; h_calib_ff) determined during the calibration phase.
2. The method according to claim 1, wherein the emission phase comprises a step (pe_node) of emission by a movable speaker (15), during which an audio signal is sent to the movable speaker (15) to be emitted by said movable speaker (15),
the calibration phase comprises a step (pc_spk) of calibrating the movable speaker (15),
during the receiving (112) of the calibration step (pc_spk), an audio signal is received from a calibration microphone (80),
during the determination (114) of the calibration step (pc_spk), the determined calibration filter (h_calib_spk) is specific to the movable speaker (15) and is referred to as speaker calibration filter (h_calib_spk).
3. The method of claim 1, wherein the movable audio device (10) comprises two movable microphones (20, 25), the two movable microphones (20, 25) comprising an inner movable microphone (20) facing the movable speaker (30) and an outer movable microphone (25) facing the outside of the movable audio device (10).
4. A method according to claim 2 and 3, wherein the calibration phase further comprises a step (pc_fb) of calibrating the internal movable microphone (20),
during the receiving (122) of the step (PC _ FB) of calibrating the internal movable microphone (20), receiving an audio signal from the internal movable microphone (20),
during the determination (124) of the step (pc_fb) of calibrating the internal movable microphone (20), the determined calibration filter (h_calib_fb) is specific to the internal movable microphone (20) and is referred to as an internal microphone calibration filter (h_calib_fb).
5. The method according to claim 4, wherein the step of calibrating the internal movable microphone (20) (pc_fb) further comprises:
-applying (123) a speaker calibration filter (h_calib_spk) to the signal received during the receiving (122) of the step (pc_fb) of calibrating the internal movable microphone (20) to form a filtered signal,
during the step of determining (124) the phase of calibrating the internal movable microphone (pc_fb), a calibration filter (h_calib_fb) of the internal microphone is determined from the filtered signal.
6. A method according to claim 3, wherein the emission phase comprises an emission phase (PE_calib) by the calibration loudspeaker (85) during which an audio signal is sent to the calibration loudspeaker (85) to be emitted by the calibration loudspeaker (85),
the calibration phase comprises a step (PC_FF) of calibrating the external movable microphone (25),
during the receiving (132) of the step (PC _ FF) of calibrating the external movable microphone (25), receiving an audio signal from the external movable microphone (25),
during the determination (134) of the step (pc_ff) of calibrating the external movable microphone (25), the determined calibration filter (h_calib_ff) is specific to the external movable microphone (25) and is referred to as external microphone calibration filter (h_calib_ff).
7. The method of claim 3, wherein the removable audio device (10) further comprises a control unit comprising an adder (35), a first connection (50) connecting the adder (35) to the removable speaker (15), a second connection (55) connecting the internal removable microphone (20) to the adder (35), and a third connection (60) connecting the external removable microphone (25) to the adder (35),
the removable audio device (10) further comprises a first predetermined filter (HFB) on the second connection (55), a second predetermined filter (HFF) on the third connection (60),
during the implementation Phase (PI), at least one of the calibration filter (H_calib_SPK; H_calib_FB; H_calib_FF) or the calibration filter (H_calib_SPK; H_calib_FB; H_calib_FF) is implemented on one of the first connection (50), the second connection (55) and the third connection (60).
8. A method according to claim 1, wherein the or each determining sub-step (114, 124, 134) comprises:
calculating a frequency error (Err (f)) between the respective received signal and a predetermined reference signal,
-detecting the extremum(s) of the frequency error (Err (f))
-for at least one detected extremum
-calculating the frequency band around the extremum (B i )，
-according to the frequency band (B i ) The frequency error (Err (f)) in the inner determines a parametrizable element filter (H) i )，
-generating a calibration filter (h_calib_spk; h_calib_fb; h_calib_ff) based on the or each parametrizable unit filter.
9. Method according to claim 8, wherein each parametrizable unit filter (H i ) The method comprises the following adjustable parameters: center frequency (f) c i ) Maximum gain (A) i ) And quality factor (Q) i )。
10. Method according to claim 8, wherein each parametrizable unit filter (H i ) Also included is a filter type selected from the group consisting of: a peak or valley filter, a graded low pass filter and a graded high pass filter.
11. The method of claim 8, wherein, for each detected extremumIn the calculation band (B) i ) During which each frequency band (B i ) From the lower limit (f 1 i ) And upper limit (f) 2 i ) It is defined that the first and second layers,
frequency band (B) i ) Lower limit (f) 1 i ) Is the previous frequency band (B i-1 ) Upper limit (f) 2 i-1 )，
The frequency band (B) is calculated according to i ) Upper limit (f) 2 i )：
Wherein the method comprises the steps of
-Is in the frequency band (B) i ) Is a frequency of the detected extremum in (c),
-is in the next frequency band (B i+1 ) Is a frequency of the detected extremum in (c),
-
-is in the frequency band (B) i ) A norm of an error estimated at a frequency of the detected extremum of (c), and
-is in the next frequency band (B i+1 ) A norm of an error estimated at a frequency of the detected extremum of (c).
12. The method according to claim 1, wherein the movable audio device (10) comprises at least two audio channels (CH 1, CH 2), each audio channel (CH 1, CH 2) comprising at least one respective movable microphone (20, 25) and a respective movable speaker (15),
the steps of the calibration method are iterated for each audio channel (CH 1, CH 2).
13. Computer program product comprising software instructions which, when executed by a computer, implement the calibration method according to any of the preceding claims.
14. A calibration system (75) for a removable audio device (10), such as a headset or a pair of headphones, the removable audio device (10) comprising at least one removable microphone (20, 25), a removable speaker (15), the removable audio device (10) being placeable in the calibration system (75),
calibration system (75) comprising a calibration microphone (80), a calibration speaker (85) and an electronic calibration device (95) executable software instructions of a computer program product according to claim 13.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR2208063A FR3138750A1 (en) | 2022-08-03 | 2022-08-03 | Method for calibrating a portable audio device, system for calibrating a portable audio device and associated computer program product |
| FR2208063 | 2022-08-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117528377A true CN117528377A (en) | 2024-02-06 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310936874.7A Pending CN117528377A (en) | 2022-08-03 | 2023-07-27 | Method for calibrating a removable audio device, and associated system and computer program product for calibrating a removable audio device |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP4319201A1 (en) |
| CN (1) | CN117528377A (en) |
| FR (1) | FR3138750A1 (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9728179B2 (en) * | 2015-10-16 | 2017-08-08 | Avnera Corporation | Calibration and stabilization of an active noise cancelation system |
| WO2019152729A1 (en) * | 2018-02-01 | 2019-08-08 | Cirrus Logic International Semiconductor Ltd. | System and method for calibrating and testing an active noise cancellation (anc) system |
| US11026034B2 (en) * | 2019-10-25 | 2021-06-01 | Google Llc | System and method for self-calibrating audio listening devices |
-
2022
- 2022-08-03 FR FR2208063A patent/FR3138750A1/en active Pending
-
2023
- 2023-07-27 CN CN202310936874.7A patent/CN117528377A/en active Pending
- 2023-08-02 EP EP23189296.9A patent/EP4319201A1/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP4319201A1 (en) | 2024-02-07 |
| FR3138750A1 (en) | 2024-02-09 |
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