WO2022000326A1 - 一种主动降噪耳机的滤波器设计方法、装置及测试设备 - Google Patents

一种主动降噪耳机的滤波器设计方法、装置及测试设备 Download PDF

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Publication number
WO2022000326A1
WO2022000326A1 PCT/CN2020/099506 CN2020099506W WO2022000326A1 WO 2022000326 A1 WO2022000326 A1 WO 2022000326A1 CN 2020099506 W CN2020099506 W CN 2020099506W WO 2022000326 A1 WO2022000326 A1 WO 2022000326A1
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Prior art keywords
microphone
transfer function
filter
feedback
frequency response
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PCT/CN2020/099506
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English (en)
French (fr)
Inventor
刘涛
朱彪
王丽
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深圳市豪恩声学股份有限公司
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Priority to PCT/CN2020/099506 priority Critical patent/WO2022000326A1/zh
Publication of WO2022000326A1 publication Critical patent/WO2022000326A1/zh

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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

Definitions

  • This application belongs to Noise-Cancellation Headphones (Noise-Cancellation Headphone) technical field, especially relates to a filter design method, device and test equipment for active noise reduction headphones.
  • Noise-cancelling headphones refer to headphones that reduce noise in the external environment.
  • Noise-cancelling headphones include active noise-cancelling headphones and passive noise-cancelling headphones.
  • Active noise reduction is to cancel the noise in the external environment by generating sound waves with the same amplitude and opposite phase as the noise in the external environment, and reduce the noise in the middle and low frequency bands, which has a significant effect.
  • Passive noise reduction is to block the noise in the external environment through sound insulation components such as earmuffs and earplugs, and generally only works on high-frequency noise above 1kHz.
  • active noise canceling headphones usually use both a feedforward filter and a feedback filter to achieve hybrid noise elimination (hybrid noise elimination).
  • hybrid noise elimination hybrid noise elimination
  • the effect of hybrid noise reduction will not be the linear superposition of the noise reduction effect of the feedforward filter and the noise reduction effect of the feedback filter, and the reduction in certain frequency bands will occur.
  • the noise effect is quite different from the expected problem.
  • the embodiments of the present application provide a filter design method, device, and testing equipment for active noise reduction headphones, so as to solve the problem of the mixed noise reduction effect in the process of designing a feedforward filter and a feedback filter in the prior art It is not the linear superposition of the noise reduction effect of the feedforward filter and the noise reduction effect of the feedback filter, and the problem that the noise reduction effect in some frequency bands is quite different from the expected.
  • a first aspect of the embodiments of the present application provides a filter design method for active noise reduction headphones, including:
  • the transfer function of the external noise to the standard microphone in the ear canal the transfer function of the speaker to the standard microphone in the ear canal, the transfer function of the external noise to the feedforward microphone, the transfer function of the external noise to the feedback microphone And the transfer function from the speaker to the feedback microphone, to correct the ideal frequency response curve of the feedforward filter;
  • the feedforward filter is designed according to the modified ideal frequency response curve of the feedforward filter.
  • a second aspect of the embodiments of the present application provides a filter design device for active noise reduction headphones, including:
  • Modification module for frequency response curve of feedback filter, transfer function of external noise to standard microphone in ear canal, transfer function of speaker to standard microphone in ear canal, transfer function of external noise to feedback microphone and speaker to feedback microphone to modify the ideal frequency response curve of the feedforward filter;
  • Design module for designing a feedforward filter based on the modified ideal frequency response curve of the feedforward filter.
  • a third aspect of the embodiments of the present application provides a testing device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, when the processor executes the computer program.
  • a fourth aspect of the embodiments of the present application provides a computer-readable storage medium, where the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the first aspect of the embodiments of the present application is implemented The steps of the filter design method for the active noise cancelling headphones described above.
  • the embodiments of the present application are based on the frequency response curve of the feedback filter, the transfer function from the external noise to the standard microphone in the ear canal, the transfer function from the speaker to the standard microphone in the ear canal, the transfer function from the external noise to the feedforward microphone, and the transfer function from the external noise to the standard microphone in the ear canal.
  • the transfer function of the feedback microphone and the transfer function from the speaker to the feedback microphone modify the ideal frequency response curve of the feedforward filter, and design the feedforward filter according to the corrected ideal frequency response curve of the feedforward filter, which can be designed separately first Feedback filter, then according to the frequency response curve of the feedback filter and the noise transfer function related to the earphone, analyze the influence on the ideal frequency response curve of the feedforward filter when the feedback filter is turned on for noise reduction, and obtain the corrected feedforward
  • the ideal frequency response curve of the filter can be designed according to the ideal frequency response curve of the modified feedforward filter, so that the hybrid noise reduction effect can meet the expected feedforward filter.
  • FIG. 1 is a schematic structural diagram of an active noise-cancelling earphone provided by an embodiment of the present application
  • FIG. 2 is a schematic structural diagram of an earphone testing system provided by an embodiment of the present application.
  • FIG. 3 is a first schematic flow chart of a filter design method for an active noise-cancelling earphone provided by an embodiment of the present application;
  • FIG. 4 is a second schematic flowchart of a filter design method for an active noise reduction earphone provided by an embodiment of the present application
  • FIG. 5 is a schematic diagram of an ideal amplitude-frequency characteristic curve of a feedforward filter provided by an embodiment of the present application and an ideal amplitude-frequency characteristic curve of the corrected feedforward filter;
  • FIG. 6 is a schematic diagram of an ideal phase-frequency characteristic curve of a feedforward filter provided by an embodiment of the present application and an ideal phase-frequency characteristic curve of the corrected feedforward filter;
  • FIG. 7 is a third schematic flowchart of a filter design method for an active noise-cancelling headset provided by an embodiment of the present application.
  • FIG. 8 is a fourth schematic flowchart of a filter design method for an active noise-cancelling headset provided by an embodiment of the present application.
  • FIG. 9 is a schematic diagram of a linear superposition curve of the noise reduction effect of the feedforward filter and the noise reduction effect of the feedback filter and a modified mixed noise reduction effect curve provided by an embodiment of the present application;
  • FIG. 10 is a schematic diagram of an ideal amplitude-frequency characteristic curve of the feedforward filter after adjusting the acoustic resistance material covering the leakage hole of the front acoustic cavity and an ideal amplitude-frequency characteristic curve of the corrected feedforward filter provided by an embodiment of the present application;
  • FIG. 11 is a schematic diagram of the ideal phase-frequency characteristic curve of the feedforward filter after adjusting the acoustic resistance material covering the leakage hole of the front acoustic cavity and the ideal phase-frequency characteristic curve of the corrected feedforward filter provided by an embodiment of the present application;
  • FIG. 12 is a schematic structural diagram of a filter design apparatus provided by an embodiment of the present application.
  • FIG. 13 is a schematic structural diagram of a testing device provided by an embodiment of the present application.
  • references in this specification to "one embodiment” or “some embodiments” and the like mean that a particular feature, structure or characteristic described in connection with the embodiment is included in one or more embodiments of the present application.
  • appearances of the phrases “in one embodiment,” “in some embodiments,” “in other embodiments,” “in other embodiments,” etc. in various places in this specification are not necessarily All refer to the same embodiment, but mean “one or more but not all embodiments” unless specifically emphasized otherwise.
  • the terms “including”, “including”, “having” and their variants mean “including but not limited to” unless specifically emphasized otherwise.
  • An embodiment of the present application provides a filter design method for an active noise reduction earphone, which is used to design a feedback filter and a feedforward filter that make the hybrid noise reduction effect of the active noise reduction earphone meet expectations.
  • the filter design method can be applied to a test device that designs and calculates performance parameters of each component in an active noise reduction earphone, and can be executed by a processor of the test device when running a computer program.
  • the test equipment may be a tablet computer, a notebook computer, a desktop computer, a personal computer (personal computer, PC) and other computing equipment with data processing and computing functions.
  • the embodiment of the present application does not limit the specific type of the test equipment.
  • active noise cancelling headphones generally include components such as a feedforward microphone, a feedforward filter, one or two speakers, a feedback microphone, and a feedback filter.
  • the ANC headset is a Bluetooth headset, it may further include a rechargeable battery and a wireless communication module; when the ANC headset is a wired headset, it may also include a headphone wire and a headphone interface. There is no restriction on the specific type of earphones.
  • the active noise reduction headset 10 includes a feedforward microphone 1 , a feedforward filter 2 , a speaker 3 , a feedback microphone 4 and a feedback filter 5, the solid arrows between the feedforward microphone 1, the feedforward filter 2, the speaker 3, the feedback microphone 4 and the feedback filter 5 indicate the transmission direction of the analog or digital signal, the external noise 6 and the feedforward microphone 1, the feedback
  • the dashed arrows between the microphone 4 and the standard microphone 7 represent the transmission direction of noise
  • the dashed arrows between the speaker 3 and the feedback microphone 4 and the standard microphone 7 represent the transmission direction of the sound signal.
  • the headphone test system generally includes speakers, artificial head (the artificial head includes one or two artificial ears), audio analyzer and test equipment. Speakers are used to emit noise to simulate the noise in the external environment.
  • the earplugs of the active noise cancelling headphones are inserted into the ear canal of the artificial ear to simulate a scenario in which the headphones of the active noise cancelling headphones are inserted into the ear canal of the human ear.
  • the audio analyzer is used to analyze the noise output by the speaker and the sound signal output by the active noise reduction headset and artificial ear respectively to obtain the frequency, amplitude, phase, signal-to-noise ratio and other parameters of the noise and sound signal.
  • the test equipment is used to analyze and calculate these parameters, and obtain the transfer function of external noise (that is, the noise output by the speaker) to the standard microphone in the ear canal, the transfer function of the speaker to the standard microphone in the ear canal, and the transfer function of the external noise to the feedforward microphone. Transfer function, transfer function of external noise to feedback microphone, transfer function of loudspeaker to feedback microphone, etc. noise transfer function related to earphones to realize the filter design method.
  • the ear canal may be the ear canal of the artificial ear or the ear canal of the human ear.
  • the artificial ear can be replaced by the human ear to obtain the transfer function of external noise to the standard microphone in the ear canal, the transfer function of the speaker to the standard microphone in the ear canal, and the transfer of external noise to the feedforward microphone when the human ear wears active noise canceling headphones function, transfer function of external noise to feedback microphone, transfer function of speaker to feedback microphone, etc.
  • Noise transfer functions related to headphones By replacing the artificial ear with the human ear, the design of the personalized active noise reduction earphone matching the human ear can be realized, and the personalized customization needs of the user can be met.
  • FIG. 2 a schematic structural diagram of a headphone test system is exemplarily shown; wherein, the headphone test system includes a speaker 20 , a simulated human head 30 , an audio analyzer and testing equipment (not shown in the figure), and the simulated human head 30 includes artificial ears 31 .
  • the filter design method for the active noise reduction headphones includes:
  • Step S301 according to the frequency response curve of the feedback filter, the transfer function of the external noise to the standard microphone in the ear canal, the transfer function of the speaker to the standard microphone in the ear canal, the transfer function of the external noise to the feedforward microphone, and the external noise to the feedback microphone and the transfer function from the speaker to the feedback microphone to correct the ideal frequency response curve of the feedforward filter.
  • the feedback filter is pre-designed before step S301 is executed, and the frequency response curve of the feedback filter, the transfer function of the external noise to the standard microphone in the ear canal, the transfer function of the speaker to the standard microphone in the ear canal, the external noise to the standard microphone
  • the transfer function of the feedback microphone and the transfer function from the speaker to the feedback microphone are known parameters measured in advance by the earphone test system.
  • the feedback filter and the feedforward filter are turned on at the same time, the feedback filter will have a certain influence on the ideal frequency response curve of the feedforward filter. Therefore, when designing the feedforward filter, it is necessary to adjust the feedback filter to the feedforward filter.
  • the ideal frequency response curve of the feedforward filter is modified taking into account the effect of the ideal frequency response curve of the filter.
  • the expression of the ideal frequency response curve of the modified feedforward filter is:
  • Hf _target _new (Tae/Tde – Hb*Nb*Tab)/(Taf*(1-Hb*Nb*Tdb));
  • Nb 1/(1+Tdb*Hb);
  • Hf_target _new represents the ideal frequency response curve of the modified feedforward filter
  • Hb represents the frequency response curve of the feedback filter
  • Tae represents the transfer function of the external noise to the standard microphone in the ear canal
  • Tde represents the transfer function from the speaker to the standard microphone in the ear canal function
  • Taf represents the transfer function from external noise to feedforward microphone
  • Tab represents the transfer function from external noise to feedback microphone
  • Tdb represents the transfer function from speaker to feedback microphone
  • Nb represents the noise at the feedback microphone when the feedback filter is used for separate noise reduction. Noise reduction rate.
  • eb1 (Tab–Tdb* Hf _target_new *Taf) * Nb; (expression two)
  • eb1 represents the ideal noise at the feedback microphone when the mixed noise reduction is performed by the feedback filter and the feedforward filter.
  • Step S302 Design a feedforward filter according to the corrected ideal frequency response curve of the feedforward filter.
  • the type, order and specific filter coefficients of the feedforward filter can be determined according to the ideal frequency response curve of the modified feedforward filter.
  • the filter type can be a Finite Impulse Response (FIR) filter or an Infinite Impulse Response (Infinite Impulse Response) filter.
  • Impulse Response, IIR) filter The filter coefficients that are closest to the ideal frequency response curve of the corrected feedforward filter in the target noise reduction frequency band are obtained through various common filter design methods.
  • step S301 includes:
  • Step S401 respectively according to the frequency response curves of several different feedback filters and the transfer function of the external noise to the standard microphone in the ear canal, the transfer function of the speaker to the standard microphone in the ear canal, the transfer function of the external noise to the feedforward microphone, the external noise
  • the transfer function of the noise to the feedback microphone and the transfer function of the speaker to the feedback microphone modify the ideal frequency response curve of the feedforward filter, and obtain a number of modified feedforward filter corresponding to the frequency response curve of several different feedback filters.
  • the ideal frequency response curve of the device
  • Step S402 selecting an ideal frequency response curve of the corrected feedforward filter whose flatness meets the preset requirement from the ideal frequency response curves of several corrected feedforward filters;
  • Step S302 includes:
  • Step S403 designing a feedforward filter according to an ideal frequency response curve of the corrected feedforward filter whose flatness meets a preset requirement.
  • the number of feedback filters that meet the design requirements may be more than one.
  • the ideal frequency response curve of the feedforward filter can be modified according to the frequency response curve of each feedback filter and the known parameters, and each feedback filter can be obtained by modifying the ideal frequency response curve.
  • the ideal frequency response curve of the modified feedforward filter corresponding to the filter is selected as the finally determined ideal frequency response curve of the modified feedforward filter.
  • the frequency response curve usually includes an amplitude-frequency characteristic curve and a phase-frequency characteristic curve.
  • the ideal frequency response curve of the corrected feedforward filter includes the ideal amplitude-frequency characteristic curve and the ideal frequency response curve of the corrected feedforward filter. Phase-frequency characteristic curve.
  • the ideal frequency response curve of the modified feedforward filter whose flatness meets a preset requirement includes:
  • the ideal amplitude-frequency characteristic curve of the modified feedforward filter whose amplitude variation in the preset frequency band is greater than the first amplitude threshold and less than the second amplitude threshold;
  • the ideal phase-frequency characteristic curve of the feedforward filter after the correction where the phase change in the preset frequency band is greater than the first phase threshold and less than the second phase threshold.
  • the ideal frequency response curve of the modified feedforward filter whose flatness meets a preset requirement includes:
  • the volume values of the preset frequency band, the first amplitude threshold, the second amplitude threshold, the first phase threshold, the second phase threshold, the preset octave, the amplitude change rate threshold and the phase change rate threshold can all be determined according to actually needs to be set up.
  • the preset frequency band can be set to 100Hz (Hertz) ⁇ 300Hz
  • the preset octave can be set to 1/3 octave
  • the amplitude change rate threshold can be set to 4dBper 1/3 octave (that is, 4dB per 1/3 octave octave)
  • the phase change rate threshold can be set to 15° per 1/3 octave (i.e. 15 degrees per 1/3 octave).
  • the first amplitude threshold is the difference between the average amplitude value in the preset frequency band and the lower limit amplitude threshold value
  • the second amplitude threshold value is the sum of the average amplitude value in the preset frequency band and the upper limit amplitude threshold value
  • the first phase threshold is the difference between the average phase value in the preset frequency band and the lower limit phase threshold value
  • the second phase threshold value is the sum of the average phase value in the preset frequency band and the upper limit phase threshold value.
  • the first amplitude threshold is equal to the difference between the average amplitude value in the preset frequency band in the curve and the preset lower limit amplitude threshold, and the second amplitude threshold
  • the amplitude threshold value is equal to the sum of the average amplitude value in the preset frequency band in the curve and the preset upper limit amplitude threshold value.
  • the first phase threshold is equal to the difference between the average phase value in the preset frequency band in the curve and the preset lower phase threshold
  • the second phase threshold It is equal to the sum of the average phase value in the preset frequency band in this curve and the preset upper phase threshold.
  • the lower amplitude threshold, the upper amplitude threshold, the lower phase threshold and the upper phase threshold can all be set in advance according to actual needs. Can be set to 30° (degrees).
  • the ideal amplitude-frequency characteristic curve of the feedforward filter (that is, the ideal amplitude-frequency characteristic curve of the feedforward filter before correction) 51 and The corrected ideal amplitude-frequency characteristic curve 52 of the feedforward filter; wherein, the ideal amplitude-frequency characteristic curve 52 of the corrected feedforward filter has a large amplitude fluctuation around 80 Hz.
  • the ideal phase-frequency characteristic curve of the feedforward filter (that is, the ideal phase-frequency characteristic curve of the feedforward filter before correction) 61 and The corrected ideal phase-frequency characteristic curve 62 of the feedforward filter; wherein, the ideal phase-frequency characteristic curve 62 of the corrected feedforward filter has a relatively large phase fluctuation around 100 Hz.
  • step S301 includes:
  • Step S701 according to the transfer function of several groups of different external noises to the standard microphone in the ear canal, the transfer function of the speaker to the standard microphone in the ear canal, the transfer function of the external noise to the feedback microphone, the transfer function of the speaker to the feedback microphone, and the feedback
  • the frequency response curve of the filter and the transfer function of the external noise to the feed-forward microphone, the ideal frequency response curve of the feed-forward filter is corrected, and the transfer function of the standard microphone from the external noise to the ear canal and the speaker to the ear canal are obtained.
  • the ideal frequency response curves of several modified feedforward filters corresponding to the transfer function of the standard microphone in the ear canal, the transfer function of external noise to the feedback microphone, and the transfer function of the speaker to the feedback microphone;
  • Step S702 selecting an ideal frequency response curve of the corrected feedforward filter whose flatness meets the preset requirement from the ideal frequency response curves of several corrected feedforward filters;
  • Step S302 including:
  • Step S703 designing a feedforward filter according to an ideal frequency response curve of the corrected feedforward filter whose flatness meets a preset requirement.
  • the transfer function of a set of external noise to the standard microphone in the ear canal corresponding to each hardware structure design scheme, and the standard microphone from the speaker to the ear canal can be obtained according to the measurement.
  • the transfer function of the external noise to the feedback microphone, the transfer function of the speaker to the feedback microphone, the frequency response curve of the feedback filter and the transfer function of the external noise to the feedforward microphone, and the ideal frequency response curve of the feedforward filter can be changed according to the measurement.
  • step S701 before step S701, it includes:
  • adjust the setting position, size, shape of the leak hole of the front acoustic cavity or the acoustic resistance material covering the leak hole of the front acoustic cavity to obtain several groups of different external noises to the standard microphone transfer function in the ear canal, speaker to the ear canal Transfer functions of standard microphones, transfer functions of external noise to feedback microphones, and transfer functions of speakers to feedback microphones.
  • the acoustic resistance material of the hole will directly affect the transfer function of the external noise to the standard microphone in the ear canal, the transfer function of the speaker to the standard microphone in the ear canal, the transfer function of the external noise to the feedback microphone and the relative transfer function of the speaker to the feedback microphone. magnitude and phase relationship, which in turn affects the shape of the ideal frequency response curve of the modified feedforward filter.
  • step S402 and step S702 include:
  • the modified forward filter From the ideal frequency response curves of several modified feed-forward filters, select the modified forward filter whose absolute value of the amplitude variation in the preset frequency band is less than or equal to the amplitude threshold and the absolute value of the phase variation is less than or equal to the phase threshold.
  • the ideal frequency response curve of the feedforward filter wherein, the modified ideal frequency response curve of the feedforward filter includes an ideal amplitude-frequency characteristic curve and an ideal phase-frequency characteristic curve of the corrected feedforward filter.
  • step S402 and step S702 are the same, the difference is only in that the execution timing of the two is different, step S402 is performed after step S401, and step S702 is performed after step S701;
  • step S403 is performed after step S402, and step S703 is performed after step S702.
  • step S302 it further includes:
  • Step S801 according to the frequency response curve of the feedback filter, the transfer function from the external noise to the standard microphone in the ear canal, the transfer function from the speaker to the standard microphone in the ear canal, the transfer function from the external noise to the feedforward microphone, and the external noise to the feedback microphone
  • the transfer function from the speaker to the feedback microphone and the actual frequency response curve of the feedforward filter are obtained, and the modified hybrid noise reduction effect curve is obtained.
  • the actual frequency response curve of the feedforward filter is based on the modified ideal frequency response curve of the feedforward filter.
  • the modified hybrid noise reduction effect curve is designed according to the ideal frequency response curve of the modified feedforward filter.
  • the frequency response curve of the external noise to the standard microphone in the ear canal, the transfer function of the speaker to the standard microphone in the ear canal, the transfer function of the external noise to the feed-forward microphone, the transfer function of the external noise to the feedback microphone, the transfer function of the speaker to the feedback is the modified mixed noise reduction effect curve.
  • the modified hybrid noise reduction effect curve may include an amplitude-frequency characteristic curve and a phase-frequency characteristic curve.
  • the expression of the modified hybrid noise reduction effect curve is:
  • ANC_hybrid 1-(eb*Hb+ Taf*Hf)*Tde/Tae;
  • eb (Tab–Tdb*Hf*Taf)*Nb;
  • ANC_hybrid represents the modified hybrid noise reduction effect curve
  • Hb represents the frequency response curve of the feedback filter
  • Hf represents the actual frequency response curve of the feedforward filter
  • Tae represents the transfer function of the external noise to the standard microphone in the ear canal
  • Tde Represents the transfer function from the speaker to the standard microphone in the ear canal
  • Taf represents the transfer function from external noise to the feedforward microphone
  • Tab represents the transfer function from external noise to the feedback microphone
  • Tdb represents the transfer function from the speaker to the feedback microphone
  • Nb represents the transfer function through feedback filtering is the noise reduction rate at the feedback microphone when the filter performs noise reduction alone
  • eb represents the noise at the feedback microphone when the feedback filter and the feedforward filter are used for mixed noise reduction.
  • the actual frequency response curve of the feedforward filter may include the actual amplitude-frequency characteristic curve and the actual phase-frequency characteristic curve of the feedforward filter.
  • a linear superposition curve 91 and a modified mixed noise reduction effect curve 92 of the noise reduction effect of the feedforward filter and the noise reduction effect of the feedback filter are exemplarily shown.
  • FIG. 10 it exemplarily shows the ideal amplitude-frequency characteristic curve 101 of the feedforward filter after adjusting the acoustic resistance material covering the leakage hole of the front acoustic cavity, and the ideal amplitude-frequency characteristic of the feedforward filter after correction Curve 102; wherein, the amplitude fluctuation of the ideal amplitude-frequency characteristic curve 102 of the corrected feedforward filter is small.
  • the ideal phase-frequency characteristic curve 111 of the feedforward filter after adjusting the acoustic resistance material covering the leakage hole of the front acoustic cavity, and the ideal phase-frequency characteristic of the feedforward filter after correction are exemplarily shown Curve 112; wherein, the ideal phase-frequency characteristic curve 112 of the corrected feedforward filter has less phase fluctuation.
  • the embodiments of the present application are based on the frequency response curve of the feedback filter, the transfer function from the external noise to the standard microphone in the ear canal, the transfer function from the speaker to the standard microphone in the ear canal, the transfer function from the external noise to the feedforward microphone, and the transfer function from the external noise to the standard microphone in the ear canal.
  • the transfer function of the feedback microphone and the transfer function from the speaker to the feedback microphone modify the ideal frequency response curve of the feedforward filter, and design the feedforward filter according to the corrected ideal frequency response curve of the feedforward filter, which can be designed separately first Feedback filter, then according to the frequency response curve of the feedback filter and the noise transfer function related to the earphone, analyze the influence on the ideal frequency response curve of the feedforward filter when the feedback filter is turned on for noise reduction, and obtain the corrected feedforward
  • the ideal frequency response curve of the filter can be designed according to the ideal frequency response curve of the modified feedforward filter, so that the hybrid noise reduction effect can meet the expected feedforward filter.
  • Embodiments of the present application further provide an apparatus for designing a filter for an active noise-cancelling earphone, which is configured to perform the steps in the above-mentioned embodiments of the method for designing a filter for an active noise-cancelling earphone.
  • the filter design device for the active noise cancelling headset can be a virtual appliance in the test equipment, run by the processor of the test equipment, or the test equipment itself.
  • the filter design device 12 for the active noise reduction headphones includes:
  • the correction module 121 is used for the frequency response curve of the feedback filter, the transfer function of the external noise to the standard microphone in the ear canal, the transfer function of the speaker to the standard microphone in the ear canal, the transfer function of the external noise to the feedback microphone, and the transfer function of the speaker to the feedback
  • the transfer function of the microphone which corrects the ideal frequency response curve of the feedforward filter
  • the design module 122 is configured to design the feedforward filter according to the modified ideal frequency response curve of the feedforward filter.
  • the filter design device for active noise cancelling headphones further includes an adjustment module for:
  • adjust the setting position, size, shape of the leak hole of the front acoustic cavity or the acoustic resistance material covering the leak hole of the front acoustic cavity to obtain several groups of different external noises to the standard microphone transfer function in the ear canal, speaker to the ear canal Transfer functions of standard microphones, transfer functions of external noise to feedback microphones, and transfer functions of speakers to feedback microphones.
  • the adjustment module is specifically used to adjust the design parameters such as the position, size, shape, material and other design parameters of each hardware structure of the active noise reduction headset when receiving the adjustment instruction input by the user through any human-computer interaction mode supported by the terminal device. .
  • each module in the filter design device can be a software program module, can also be implemented by different logic circuits integrated in the processor, and can also be implemented by multiple distributed processors.
  • an embodiment of the present application further provides a test device 13 , including: at least one processor 131 (only one processor is shown in FIG. 13 ), a memory 132 , and a test device 132 stored in the memory 132 and available in at least one
  • the computer program 133 running on the processor 131 when the processor 131 executes the computer program 133, implements the steps in any of the foregoing filter design method embodiments.
  • the test equipment may include, but is not limited to, a processor and a memory.
  • FIG. 13 is only an example of the test equipment, and does not constitute a limitation to the test equipment. It may include more or less components than the one shown in the figure, or combine some components, or different components, such as It can also include input and output devices, network access devices, and the like.
  • the processor may be a central processing unit (Central Processing Unit, CPU), and the processor may also be other general-purpose processors, digital signal processors (Digital Signal Processors, DSP), application-specific integrated circuits (Application Specific Integrated Circuit, ASIC), off-the-shelf Programmable Gate Array (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.
  • a general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
  • the memory may in some embodiments be an internal storage unit of the test device, such as a hard disk or memory of the test device.
  • the memory may also be an external storage device of the test equipment, such as a plug-in hard disk equipped on the test equipment, a Smart Media Card (SMC), a Secure Digital (SD) card, a flash memory Card (Flash Card), etc.
  • the memory may also include both an internal storage unit of the test equipment and an external storage device.
  • the memory is used to store operating systems, application programs, bootloaders (BootLoaders), data, and other programs, such as program codes of computer programs, and the like.
  • the memory may also be used to temporarily store data that has been or will be output.
  • Embodiments of the present application further provide a test device, the test device includes: at least one processor, a memory, and a computer program stored in the memory and executable on the at least one processor, the processor executing The computer program implements the steps in each of the above-mentioned embodiments of the filter design method for active noise reduction headphones.
  • Embodiments of the present application further provide a computer-readable storage medium, where a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, a filter design method capable of implementing each of the above-mentioned active noise reduction headphones is implemented steps in the examples.
  • Embodiments of the present application provide a computer program product, which, when the computer program product runs on a test device, enables the test device to implement the steps in each of the above filter design method embodiments for active noise reduction headphones.
  • the integrated modules are implemented in the form of software functional modules and sold or used as independent products, they may be stored in a computer-readable storage medium.
  • the present application realizes all or part of the processes in the methods of the above embodiments, which can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium.
  • the computer program includes computer program code
  • the computer program code may be in the form of source code, object code, executable file or some intermediate form, and the like.
  • the computer-readable medium may include at least: any entity or device capable of carrying the computer program code to the test equipment, recording medium, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electrical carrier signals, telecommunication signals, and software distribution media.
  • ROM read-only memory
  • RAM random access memory
  • electrical carrier signals telecommunication signals
  • software distribution media For example, U disk, mobile hard disk, disk or CD, etc.
  • testing apparatus and method may be implemented in other manners.
  • the test equipment embodiments described above are only illustrative.
  • the division of the modules is only a logical function division. In actual implementation, there may be other division methods.
  • multiple modules or components may be combined. Either it can be integrated into another system, or some features can be omitted, or not implemented.
  • the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or modules, and may be in electrical, mechanical or other forms.
  • modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, that is, may be located in one place, or may be distributed to multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution in this embodiment.

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Abstract

本申请提供一种主动降噪耳机的滤波器设计方法、装置及测试设备。本申请通过预先设计反馈滤波器，再根据反馈滤波器的频率响应曲线、外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到前馈麦克风的传递函数、外部噪声到反馈麦克风的传递函数及扬声器到反馈麦克风的传递函数，分析打开反馈滤波器进行降噪时对前馈滤波器的理想频率响应曲线的影响，对前馈滤波器的理想频率响应曲线进行修正，从而可以根据修正后的前馈滤波器的理想频率响应曲线设计混合降噪效果符合预期的前馈滤波器。

Description

一种主动降噪耳机的滤波器设计方法、装置及测试设备 技术领域
本申请属于降噪耳机（Noise-Cancellation Headphone）技术领域，尤其涉及一种主动降噪耳机的滤波器设计方法、装置及测试设备。
 背景技术
降噪耳机是指能够降低外部环境中的噪声的耳机。降噪耳机包括主动降噪耳机和被动降噪耳机两种。主动降噪是通过扬声器产生与外部环境中的噪声幅度相同且相位反向的声波，来抵消外部环境中的噪声，降低对中低频段的噪声有明显的效果。被动降噪是通过耳套、耳塞等隔音部件来阻挡外部环境中的噪声，一般只对1kHz以上的高频噪声起作用。
目前，为了实现良好的降噪效果，主动降噪耳机通常会同时使用前馈滤波器和反馈滤波器来实现混合降噪（hybrid noise eliminating）。然而，在设计前馈滤波器和反馈滤波器的过程中，会出现混合降噪的效果不是前馈滤波器的降噪效果和反馈滤波器的降噪效果的线性叠加、在某些频段的降噪效果与预期差异较大的问题。
 技术问题
本申请实施例提供了一种主动降噪耳机的滤波器设计方法、装置及测试设备，以解决现有技术中在设计前馈滤波器和反馈滤波器的过程中，会出现混合降噪的效果不是前馈滤波器的降噪效果和反馈滤波器的降噪效果的线性叠加、在某些频段的降噪效果与预期差异较大的问题。
 技术解决方案
本申请实施例的第一方面提供了一种主动降噪耳机的滤波器设计方法，包括：
根据反馈滤波器的频率响应曲线、外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到前馈麦克风的传递函数、外部噪声到反馈麦克风的传递函数及扬声器到反馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正；
根据修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器。
本申请实施例的第二方面提供了一种主动降噪耳机的滤波器设计装置，包括：
修正模块，用于根据反馈滤波器的频率响应曲线、外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数及扬声器到反馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正；
设计模块，用于根据修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器。
本申请实施例的第三方面提供了一种测试设备，包括存储器、处理器以及存储在所述存储器中并可在所述处理器上运行的计算机程序，所述处理器执行所述计算机程序时实现如本申请实施例的第一方面所述的主动降噪耳机的滤波器设计方法的步骤。
本申请实施例的第四方面提供了一种计算机可读存储介质，所述计算机可读存储介质存储有计算机程序，所述计算机程序被处理器执行时实现如本申请实施例的第一方面所述的主动降噪耳机的滤波器设计方法的步骤。
 有益效果
本申请实施例通过根据反馈滤波器的频率响应曲线、外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到前馈麦克风的传递函数、外部噪声到反馈麦克风的传递函数及扬声器到反馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正，根据修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器，可以先单独设计反馈滤波器，然后根据反馈滤波器的频率响应曲线及与耳机相关的噪声传递函数，分析打开反馈滤波器进行降噪时对前馈滤波器的理想频率响应曲线的影响，获得修正后的前馈滤波器的理想频率响应曲线，从而可以根据修正后的前馈滤波器的理想频率响应曲线设计使得混合降噪效果符合预期的前馈滤波器。
可以理解的是，上述第二方面至第四方面的有益效果可以参见上述第一方面中的相关描述，在此不再赘述。
 附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本申请实施例提供的主动降噪耳机的结构示意图；
图2是本申请实施例提供的耳机测试系统的结构示意图；
图3是本申请实施例提供的主动降噪耳机的滤波器设计方法的第一种流程示意图；
图4是本申请实施例提供的主动降噪耳机的滤波器设计方法的第二种流程示意图；
图5是本申请实施例提供的前馈滤波器的理想幅频特性曲线和修正后的前馈滤波器的理想幅频特性曲线的示意图；
图6是本申请实施例提供的前馈滤波器的理想相频特性曲线和修正后的前馈滤波器的理想相频特性曲线的示意图；
图7是本申请实施例提供的主动降噪耳机的滤波器设计方法的第三种流程示意图；
图8是本申请实施例提供的主动降噪耳机的滤波器设计方法的第四种流程示意图；
图9是本申请实施例提供的前馈滤波器的降噪效果和反馈滤波器的降噪效果的线性叠加曲线以及修正后的混合降噪效果曲线的示意图；
图10是本申请实施例提供的调节覆盖于前声腔的泄露孔的声阻材料后的前馈滤波器的理想幅频特性曲线和修正后的前馈滤波器的理想幅频特性曲线的示意图；
图11是本申请实施例提供的调节覆盖于前声腔的泄露孔的声阻材料后的前馈滤波器的理想相频特性曲线和修正后的前馈滤波器的理想相频特性曲线的示意图；
图12是本申请实施例提供的滤波器设计装置的结构示意图；
图13是本申请实施例提供的测试设备的结构示意图。
 本发明的实施方式
以下描述中，为了说明而不是为了限定，提出了诸如特定系统结构、技术之类的具体细节，以便透彻理解本申请实施例。然而，本领域的技术人员应当清楚，在没有这些具体细节的其它实施例中也可以实现本申请。在其它情况中，省略对众所周知的系统、装置、电路以及方法的详细说明，以免不必要的细节妨碍本申请的描述。
应当理解，当在本申请说明书和所附权利要求书中使用时，术语“包括”指示所描述特征、整体、步骤、操作、元素和/或组件的存在，但并不排除一个或多个其它特征、整体、步骤、操作、元素、组件和/或其集合的存在或添加。
另外，在本申请说明书和所附权利要求书的描述中，术语“第一”、“第二”、“第三”等仅用于区分描述，而不能理解为指示或暗示相对重要性。
在本申请说明书中描述的参考“一个实施例”或“一些实施例”等意味着在本申请的一个或多个实施例中包括结合该实施例描述的特定特征、结构或特点。由此，在本说明书中的不同之处出现的语句“在一个实施例中”、“在一些实施例中”、“在其他一些实施例中”、“在另外一些实施例中”等不是必然都参考相同的实施例，而是意味着“一个或多个但不是所有的实施例”，除非是以其他方式另外特别强调。术语“包括”、“包含”、“具有”及它们的变形都意味着“包括但不限于”，除非是以其他方式另外特别强调。
本申请实施例一种主动降噪耳机的滤波器设计方法，用于设计使得主动降噪耳机的混合降噪效果符合预期的反馈滤波器和前馈滤波器。滤波器设计方法可以应用于对主动降噪耳机中各部件的性能参数进行设计和计算的测试设备，可以由测试设备的处理器在运行计算机程序时执行。测试设备可以是平板电脑、笔记本电脑、桌上型计算机、个人计算机（personal computer，PC）等具有数据处理和计算功能的计算设备，本申请实施例对测试设备的具体类型不作任何限制。
在应用中，主动降噪耳机一般包括前馈麦克风、前馈滤波器、一或两个扬声器、反馈麦克风和反馈滤波器等部件。当主动降噪耳机为蓝牙耳机时，其还可以包括可充电电池和无线通信模块；当主动降噪耳机为有线耳机时，其还可以包括耳机导线和耳机接口，本申请实施例对主动降噪耳机的具体类型不作任何限制。
如图1所示，示例性的示出了一种主动降噪耳机的结构示意图；其中，主动降噪耳机10包括前馈麦克风1、前馈滤波器2、扬声器3、反馈麦克风4及反馈滤波器5，前馈麦克风1、前馈滤波器2、扬声器3、反馈麦克风4及反馈滤波器5之间的实线箭头表示模拟或数字信号的传输方向，外部噪声6与前馈麦克风1、反馈麦克风4及标准麦克风7之间的虚线箭头表示噪声的传输方向，扬声器3与反馈麦克风4和标准麦克风7之间的虚线箭头表示声音信号的传输方向。
在应用中，在对主动降噪耳机的滤波器进行设计的过程中，需要使用耳机测试系统对主动降噪耳机的性能进行测试。耳机测试系统一般包括用于音箱、仿真人头（仿真人头包括一或两个仿真耳）、音频分析仪及测试设备等。音箱用于发出噪声，以模拟外部环境中的噪声。主动降噪耳机的耳塞插入仿真耳的耳道，以模拟主动降噪耳机的耳机插入人耳的耳道的场景。音频分析仪用于分别对音箱输出的噪声以及主动降噪耳机和仿真耳输出的声音信号进行分析，以获得噪声和声音信号的频率、幅度、相位、信噪比等参数。测试设备用于对这些参数进行分析和计算，获得外部噪声（即音箱输出的噪声）到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到前馈麦克风的传递函数、外部噪声到反馈麦克风的传递函数、扬声器到反馈麦克风的传递函数等与耳机相关的噪声传递函数，以实现滤波器设计方法。
在应用中，耳道可以是仿真耳的耳道，也可以是人耳的耳道。可以将仿真耳替换为人耳，以获得人耳佩戴主动降噪耳机时，外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到前馈麦克风的传递函数、外部噪声到反馈麦克风的传递函数、扬声器到反馈麦克风的传递函数等与耳机相关的噪声传递函数。通过将仿真耳替换为人耳，可以实现与人耳匹配的个性化的主动降噪耳机的设计，可以满足用户的个性化定制需求。
如图2所示，示例性的示出了一种耳机测试系统的结构示意图；其中，耳机测试系统包括音箱20、仿真人头30、音频分析仪及测试设备（图中未示出），仿真人头30包括仿真耳31。
如图3所示，本申请实施例提供的主动降噪耳机的滤波器设计方法，包括：
步骤S301、根据反馈滤波器的频率响应曲线、外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到前馈麦克风的传递函数、外部噪声到反馈麦克风的传递函数及扬声器到反馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正。
在应用中，反馈滤波器在执行步骤S301之前预先设计完成，反馈滤波器的频率响应曲线、外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数及扬声器到反馈麦克风的传递函数均为通过耳机测试系统预先测量得到的已知参数。由于同时打开反馈滤波器和前馈滤波器时，反馈滤波器会对前馈滤波器的理想频率响应曲线产生一定的影响，因此，在设计前馈滤波器时，需要将反馈滤波器对前馈滤波器的理想频率响应曲线的产生的影响考虑在内，对前馈滤波器的理想频率响应曲线进行修正。
在一个实施例中，所述修正后的前馈滤波器的理想频率响应曲线的表达式为：
Hf _target _new=（Tae/Tde–Hb*Nb*Tab）/（Taf*（1 -Hb*Nb*Tdb））；
Nb=1/（1+Tdb*Hb）；
其中，Hf_target _new表示修正后的前馈滤波器的理想频率响应曲线，Hb表示反馈滤波器的频率响应曲线，Tae表示外部噪声到耳道中的标准麦克风的传递函数，Tde表示扬声器到耳道中的标准麦克风的传递函数，Taf 表示外部噪声到前馈麦克风的传递函数，Tab表示外部噪声到反馈麦克风的传递函数，Tdb表示扬声器到反馈麦克风的传递函数，Nb表示通过反馈滤波器进行单独降噪时反馈麦克风处的降噪率。
在应用中，修正后的前馈滤波器的理想频率响应曲线的表达式的推导过程如下：
1）设耳道中的标准麦克风处的总残余噪声为0，其表达式为：
Tae-eb1*Hb*Tde-Taf* Hf _target _new* Tde=0；（表达式一）
2）通过反馈滤波器和前馈滤波器进行混合降噪时反馈麦克风处的理想噪声的表达式为：
eb1=（Tab–Tdb* Hf _target_new *Taf）* Nb；（表达式二）
3）将表达式二代入表达式一得到修正后的前馈滤波器的理想频率响应曲线的表达式；
其中，eb1表示通过反馈滤波器和前馈滤波器进行混合降噪时反馈麦克风处的理想噪声。
步骤S302、根据修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器。
在应用中，在获得修正后的前馈滤波器的理想频率响应曲线之后，即可根据修正后的前馈滤波器的理想频率响应曲线确定前馈滤波器的类型、阶数和具体滤波器系数。滤波器类型可以是有限脉冲响应（Finite Impulse Response，FIR）滤波器，也可以是无线冲击响应（Infinite Impulse Response，IIR）滤波器。通过通用的各类滤波器设计手段，取得在目标降噪频带与修正后的前馈滤波器的理想频率响应曲线最接近的滤波器系数。
如图4所示，在一个实施例中，步骤S301包括：
步骤S401、分别根据若干不同的反馈滤波器的频率响应曲线以及外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到前馈麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正，获得与若干不同的反馈滤波器的频率响应曲线对应的若干修正后的前馈滤波器的理想频率响应曲线；
步骤S402、从若干修正后的前馈滤波器的理想频率响应曲线中选择平坦度符合预设要求的修正后的前馈滤波器的理想频率响应曲线；
步骤S302包括：
步骤S403、根据平坦度符合预设要求的修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器。
在应用中，在预先设计反馈滤波器时，符合设计要求的反馈滤波器的数量可能不止一个。当存在两个及以上符合设计要求的反馈滤波器时，可以分别根据每个反馈滤波器的频率响应曲线以及已知参数，对前馈滤波器的理想频率响应曲线进行修正，获得与每个反馈滤波器对应的修正后的前馈滤波器的理想频率响应曲线。然后从中选择一个平坦度符合预设要求的修正后的前馈滤波器的理想频率响应曲线，作为最终确定的修正后的前馈滤波器的理想频率响应曲线。
在应用中，频率响应曲线通常包括幅频特性曲线和相频特性曲线，对应的，修正后的前馈滤波器的理想频率响应曲线包括修正后的前馈滤波器的理想幅频特性曲线和理想相频特性曲线。
在一个实施例中，平坦度符合预设要求的修正后的前馈滤波器的理想频率响应曲线包括：
在预设频段内的幅度变化量大于第一幅度阈值且小于第二幅度阈值的修正后的前馈滤波器的理想幅频特性曲线；以及
在预设频段内的相位变化量大于第一相位阈值且小于第二相位阈值的修正后的前馈滤波器的理想相频特性曲线。
在另一个实施例中，平坦度符合预设要求的修正后的前馈滤波器的理想频率响应曲线包括：
在预设频段内的每个预设倍频程的斜率的绝对值小于幅度变化率阈值的修正后的前馈滤波器的理想幅频特性曲线；以及
在预设频段内的每个预设倍频程的斜率的绝对值小于相位变化率阈值的修正后的前馈滤波器的理想相频特性曲线。
在应用中，预设频段、第一幅度阈值、第二幅度阈值、第一相位阈值、第二相位阈值、预设倍频程、幅度变化率阈值以及相位变化率阈值的体数值都可以预先根据实际需要进行设置。例如，预设频段可以设置为100Hz（赫兹）~300Hz，预设倍频程可以设置为1/3倍频程，幅度变化率阈值可以设置为4dBper 1/3 octave（即4分贝每1/3倍频程），相位变化率阈值可以设置为15°per 1/3 octave（即15度每1/3倍频程）。
在一个实施例中，所述第一幅度阈值为在预设频段内的平均幅度值与下限幅度阈值之差，所述第二幅度阈值为预设频段内的平均幅度值与上限幅度阈值之和；
所述第一相位阈值为在预设频段内的平均相位值与下限相位阈值之差，所述第二相位阈值为预设频段内的平均相位值与上限相位阈值之和。
在应用中，对于每条修正后的前馈滤波器的理想幅频特性曲线，第一幅度阈值等于该条曲线中预设频段内的平均幅度值与预先设置的下限幅度阈值之差，第二幅度阈值等于该条曲线中预设频段内的平均幅度值与预先设置的上限幅度阈值之和。同理，对于每条修正后的前馈滤波器的理想相位特性曲线，第一相位阈值等于该条曲线中预设频段内的平均相位值与预先设置的下限相位阈值之差，第二相位阈值等于该条曲线中预设频段内的平均相位值与预先设置的上限相位阈值之和。下限幅度阈值、上限幅度阈值、下限相位阈值和上限相位阈值都可以预先根据实际需要进行设置，例如，下限幅度阈值和上限幅度阈值都可以设置为8dB（分贝）、下限相位阈值和上限相位阈值都可以设置为30°（度）。
如图5所示，示例性的示出了通过前馈滤波器进行单独降噪时前馈滤波器的理想幅频特性曲线（即修正前的前馈滤波器的理想幅频特性曲线）51和修正后的前馈滤波器的理想幅频特性曲线52；其中，修正后的前馈滤波器的理想幅频特性曲线52在80Hz左右幅度波动较大。
如图6所示，示例性的示出了通过前馈滤波器进行单独降噪时前馈滤波器的理想相频特性曲线（即修正前的前馈滤波器的理想相频特性曲线）61和修正后的前馈滤波器的理想相频特性曲线62；其中，修正后的前馈滤波器的理想相频特性曲线62在100Hz左右相位波动较大。
如图7所示，在一个实施例中，步骤S301包括：
步骤S701、分别根据若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数以及反馈滤波器的频率响应曲线和外部噪声到前馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正，获得与若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数对应的若干修正后的前馈滤波器的理想频率响应曲线；
步骤S702、从若干修正后的前馈滤波器的理想频率响应曲线中选择平坦度符合预设要求的修正后的前馈滤波器的理想频率响应曲线；
步骤S302，包括：
步骤S703、根据平坦度符合预设要求的修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器。
在应用中，在预先测量得到的已知参数之前，需要预先对主动降噪耳机的反馈麦克风的设置位置、反馈麦克风的声孔方向、耳塞的出声嘴形状、前声腔的泄露孔的设置位置、大小、形状以及覆盖于前声腔的泄露孔的声阻材料进行设计。这些硬件结构设计直接影响外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数的相对大小和相位关系。因此，可以通过改变主动降噪耳机的硬件结构设计，来改变这些已知参数。当存在两种及以上不同的硬件结构设计方案时，从而可以分别根据测量得到与每种硬件结构设计方案对应的一组外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数以及反馈滤波器的频率响应曲线和外部噪声到前馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正，获得每组外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数对应的修正后的前馈滤波器的理想频率响应曲线。然后从中选择一个平坦度符合预设要求的修正后的前馈滤波器的理想频率响应曲线，作为最终确定的修正后的前馈滤波器的理想频率响应曲线。
在一个实施例中，步骤S701之前包括：
调节反馈麦克风的设置位置和反馈麦克风的声孔方向，获得若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数；
或者，调节耳塞的出声嘴形状，获得若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数；
或者，调节前声腔的泄露孔的设置位置、大小、形状或覆盖于前声腔的泄露孔的声阻材料，获得若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数。
在应用中，调节反馈麦克风的设置位置和反馈麦克风的声孔方向，或者，调节耳塞的出声嘴形状，或者，调节前声腔的泄露孔的设置位置、大小、形状或覆盖于前声腔的泄露孔的声阻材料，都会直接影响外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数的相对大小和相位关系，进而影响修正后的前馈滤波器的理想频率响应曲线的形状。
在一个实施例中，步骤S402和步骤S702包括：
从若干修正后的前馈滤波器的理想频率响应曲线中选择在预设频段内的幅度变化量的绝对值小于或等于幅度阈值且相位变化量的绝对值小于或等于相位阈值的修正后的前馈滤波器的理想频率响应曲线；其中，所述修正后的前馈滤波器的理想频率响应曲线包括修正后的前馈滤波器的理想幅频特性曲线和理想相频特性曲线。
在应用中，步骤S402和步骤S702所执行的操作相同，区别仅在于二者的执行时机不同，步骤S402在步骤S401之后执行，步骤S702在步骤S701之后执行；同理，步骤S403和步骤S703所执行的操作相同，区别仅在于二者的执行时机不同，步骤S403在步骤S402之后执行，步骤S703在步骤S702之后执行。
如图8所示，在一个实施例中，步骤S302之后，还包括：
步骤S801、根据反馈滤波器的频率响应曲线、外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到前馈麦克风的传递函数、外部噪声到反馈麦克风的传递函数、扬声器到反馈麦克风的传递函数及前馈滤波器的实际频率响应曲线，获得修正后的混合降噪效果曲线。
在应用中，前馈滤波器的实际频率响应曲线是根据修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器之后，在同时通过反馈滤波器和前馈滤波器进行混合降噪时，根据耳机测试系统实际测量得到的前馈滤波器的频率响应绘制的频率响应曲线。修正后的混合降噪效果曲线是根据修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器之后，在同时通过反馈滤波器和前馈滤波器进行混合降噪时，根据反馈滤波器的频率响应曲线、外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到前馈麦克风的传递函数、外部噪声到反馈麦克风的传递函数、扬声器到反馈麦克风的传递函数及前馈滤波器的实际频率响应曲线计算得到的用于反应反馈滤波器和前馈滤波器的混合降噪效果的曲线，即得到修正后的混合降噪效果曲线。修正后的混合降噪效果曲线可以包括幅频特性曲线和相频特性曲线。
在一个实施例中，所述修正后的混合降噪效果曲线的表达式为：
ANC_hybrid =1-（eb* Hb + Taf*Hf）*Tde/Tae；
eb=（Tab–Tdb* Hf*Taf）* Nb；
其中，ANC_hybrid表示修正后的混合降噪效果曲线，Hb表示反馈滤波器的频率响应曲线，Hf表示前馈滤波器的实际频率响应曲线，Tae表示外部噪声到耳道中的标准麦克风的传递函数，Tde表示扬声器到耳道中的标准麦克风的传递函数，Taf 表示外部噪声到前馈麦克风的传递函数，Tab表示外部噪声到反馈麦克风的传递函数，Tdb表示扬声器到反馈麦克风的传递函数，Nb表示通过反馈滤波器进行单独降噪时反馈麦克风处的降噪率，eb表示通过反馈滤波器和前馈滤波器进行混合降噪时反馈麦克风处的噪声。
在应用中，前馈滤波器的实际频率响应曲线可以包括前馈滤波器的实际幅频特性曲线和实际相频特性曲线。
如图9所示，示例性的示出了前馈滤波器的降噪效果和反馈滤波器的降噪效果的线性叠加曲线91以及修正后的混合降噪效果曲线92。
如图10所示，示例性的示出了调节覆盖于前声腔的泄露孔的声阻材料后的前馈滤波器的理想幅频特性曲线101、修正后的前馈滤波器的理想幅频特性曲线102；其中，修正后的前馈滤波器的理想幅频特性曲线102幅度波动较小。
如图11所示，示例性的示出了调节覆盖于前声腔的泄露孔的声阻材料后的前馈滤波器的理想相频特性曲线111、修正后的前馈滤波器的理想相频特性曲线112；其中，修正后的前馈滤波器的理想相频特性曲线112相位波动较小。
本申请实施例通过根据反馈滤波器的频率响应曲线、外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到前馈麦克风的传递函数、外部噪声到反馈麦克风的传递函数及扬声器到反馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正，根据修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器，可以先单独设计反馈滤波器，然后根据反馈滤波器的频率响应曲线及与耳机相关的噪声传递函数，分析打开反馈滤波器进行降噪时对前馈滤波器的理想频率响应曲线的影响，获得修正后的前馈滤波器的理想频率响应曲线，从而可以根据修正后的前馈滤波器的理想频率响应曲线设计使得混合降噪效果符合预期的前馈滤波器。
应理解，上述实施例中各步骤的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定，而不应对本申请实施例的实施过程构成任何限定。
本申请实施例还提供一种主动降噪耳机的滤波器设计装置，用于执行上述主动降噪耳机的滤波器设计方法实施例中的步骤。主动降噪耳机的滤波器设计装置可以是测试设备中的虚拟装置（virtual appliance），由测试设备的处理器运行，也可以是测试设备本身。
如图12所示，本申请实施例提供的主动降噪耳机的滤波器设计装置12，包括：
修正模块121，用于根据反馈滤波器的频率响应曲线、外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数及扬声器到反馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正；
设计模块122，用于根据修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器。
在一个实施例中，所述主动降噪耳机的滤波器设计装置还包括调节模块，用于：
调节反馈麦克风的设置位置和反馈麦克风的声孔方向，获得若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数；
或者，调节耳塞的出声嘴形状，获得若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数；
或者，调节前声腔的泄露孔的设置位置、大小、形状或覆盖于前声腔的泄露孔的声阻材料，获得若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数。
在应用中，调节模块具体用于在接收到用户通过终端设备所支持的任意人机交互方式输入的调节指令时，调节主动降噪耳机的各硬件结构的位置、大小、形状、材料等设计参数。
在应用中，滤波器设计装置中的各模块可以为软件程序模块，也可以通过处理器中集成的不同逻辑电路实现，还可以通过多个分布式处理器实现。
如图13所示，本申请实施例还提供一种测试设备13，包括：至少一个处理器131（图13中仅示出一个处理器）、存储器132以及存储在存储器132中并可在至少一个处理器131上运行的计算机程序133，处理器131执行计算机程序133时实现上述任意各个滤波器设计方法实施例中的步骤。
在应用中，该测试设备可包括，但不仅限于，处理器、存储器。本领域技术人员可以理解，图13仅仅是测试设备的举例，并不构成对测试设备的限定，可以包括比图示更多或更少的部件，或者组合某些部件，或者不同的部件，例如还可以包括输入输出设备、网络接入设备等。
在应用中，处理器可以是中央处理单元（Central Processing Unit，CPU），该处理器还可以是其他通用处理器、数字信号处理器（Digital Signal Processor，DSP）、专用集成电路（Application Specific Integrated Circuit，ASIC）、现成可编程门阵列（Field-Programmable Gate Array，FPGA）或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件等。通用处理器可以是微处理器或者该处理器也可以是任何常规的处理器等。
在应用中，存储器在一些实施例中可以是测试设备的内部存储单元，例如测试设备的硬盘或内存。存储器在另一些实施例中也可以是测试设备的外部存储设备，例如测试设备上配备的插接式硬盘，智能存储卡（Smart Media Card，SMC），安全数字（Secure Digital，SD）卡，闪存卡（Flash Card）等。进一步地，存储器还可以既包括测试设备的内部存储单元也包括外部存储设备。存储器用于存储操作系统、应用程序、引导装载程序（BootLoader）、数据以及其他程序等，例如计算机程序的程序代码等。存储器还可以用于暂时地存储已经输出或者将要输出的数据。
需要说明的是，上述装置/模块之间的信息交互、执行过程等内容，由于与本申请方法实施例基于同一构思，其具体功能及带来的技术效果，具体可参见方法实施例部分，此处不再赘述。
所属领域的技术人员可以清楚地了解到，为了描述的方便和简洁，仅以上述各功能模块的划分进行举例说明，实际应用中，可以根据需要而将上述功能分配由不同的功能模块完成，即将装置的内部结构划分成不同的功能模块，以完成以上描述的全部或者部分功能。实施例中的各功能模块可以集成在一个处理模块中，也可以是各个模块单独物理存在，也可以两个或两个以上模块集成在一个模块中，上述集成的模块既可以采用硬件的形式实现，也可以采用软件功能模块的形式实现。另外，各功能模块的具体名称也只是为了便于相互区分，并不用于限制本申请的保护范围。上述系统中模块的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
本申请实施例还提供了一种测试设备，该测试设备包括：至少一个处理器、存储器以及存储在所述存储器中并可在所述至少一个处理器上运行的计算机程序，所述处理器执行所述计算机程序时实现上述各个主动降噪耳机的滤波器设计方法实施例中的步骤。
本申请实施例还提供了一种计算机可读存储介质，所述计算机可读存储介质存储有计算机程序，所述计算机程序被处理器执行时实现可实现上述各个主动降噪耳机的滤波器设计方法实施例中的步骤。
本申请实施例提供了一种计算机程序产品，当计算机程序产品在测试设备上运行时，使得测试设备执行时实现可实现上述各个主动降噪耳机的滤波器设计方法实施例中的步骤。
所述集成的模块如果以软件功能模块的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请实现上述实施例方法中的全部或部分流程，可以通过计算机程序来指令相关的硬件来完成，所述的计算机程序可存储于一计算机可读存储介质中，该计算机程序在被处理器执行时，可实现上述各个方法实施例的步骤。其中，所述计算机程序包括计算机程序代码，所述计算机程序代码可以为源代码形式、对象代码形式、可执行文件或某些中间形式等。所述计算机可读介质至少可以包括：能够将计算机程序代码携带到测试设备的任何实体或装置、记录介质、计算机存储器、只读存储器（ROM，Read-Only Memory）、随机存取存储器（RAM，Random Access Memory）、电载波信号、电信信号以及软件分发介质。例如U盘、移动硬盘、磁碟或者光盘等。
在上述实施例中，对各个实施例的描述都各有侧重，某个实施例中没有详述或记载的部分，可以参见其它实施例的相关描述。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的模块及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
在本申请所提供的实施例中，应该理解到，所揭露的测试设备和方法，可以通过其它的方式实现。例如，以上所描述的测试设备实施例仅仅是示意性的，例如，所述模块的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个模块或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通讯连接可以是通过一些接口，装置或模块的间接耦合或通讯连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的模块可以是或者也可以不是物理上分开的，作为模块显示的部件可以是或者也可以不是物理模块，即可以位于一个地方，或者也可以分布到多个网络模块上。可以根据实际的需要选择其中的部分或者全部模块来实现本实施例方案的目的。
以上所述实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的精神和范围，均应包含在本申请的保护范围之内。

Claims (20)

  1. 一种主动降噪耳机的滤波器设计方法，其特征在于，包括：
    根据反馈滤波器的频率响应曲线、外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到前馈麦克风的传递函数、外部噪声到反馈麦克风的传递函数及扬声器到反馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正；
    根据修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器。
  2. 如权利要求1所述的主动降噪耳机的滤波器设计方法，其特征在于，所述根据反馈滤波器的频率响应曲线、外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到前馈麦克风的传递函数、外部噪声到反馈麦克风的传递函数及扬声器到反馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正，包括：
    分别根据若干不同的反馈滤波器的频率响应曲线以及外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到前馈麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正，获得与若干不同的反馈滤波器的频率响应曲线对应的若干修正后的前馈滤波器的理想频率响应曲线；
    从若干修正后的前馈滤波器的理想频率响应曲线中选择平坦度符合预设要求的修正后的前馈滤波器的理想频率响应曲线；
    所述根据修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器，包括：
    根据平坦度符合预设要求的修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器。
  3. 如权利要求1所述的主动降噪耳机的滤波器设计方法，其特征在于，所述根据反馈滤波器的频率响应曲线、外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到前馈麦克风的传递函数、外部噪声到反馈麦克风的传递函数及扬声器到反馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正，包括：
    分别根据若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数以及反馈滤波器的频率响应曲线和外部噪声到前馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正，获得与若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数对应的若干修正后的前馈滤波器的理想频率响应曲线；
    从若干修正后的前馈滤波器的理想频率响应曲线中选择平坦度符合预设要求的修正后的前馈滤波器的理想频率响应曲线；
    所述根据修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器，包括：
    根据平坦度符合预设要求的修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器。
  4. 如权利要求3所述的主动降噪耳机的滤波器设计方法，其特征在于，所述分别根据若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数以及反馈滤波器的频率响应曲线和外部噪声到前馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正，获得与若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数对应的若干修正后的前馈滤波器的理想频率响应曲线之前，包括：
    调节反馈麦克风的设置位置和反馈麦克风的声孔方向，获得若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数。
  5. 如权利要求3所述的主动降噪耳机的滤波器设计方法，其特征在于，所述分别根据若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数以及反馈滤波器的频率响应曲线和外部噪声到前馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正，获得与若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数对应的若干修正后的前馈滤波器的理想频率响应曲线之前，包括：
    调节耳塞的出声嘴形状，获得若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数。
  6. 如权利要求3所述的主动降噪耳机的滤波器设计方法，其特征在于，所述分别根据若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数以及反馈滤波器的频率响应曲线和外部噪声到前馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正，获得与若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数对应的若干修正后的前馈滤波器的理想频率响应曲线之前，包括：
    调节前声腔的泄露孔的设置位置、大小、形状或覆盖于前声腔的泄露孔的声阻材料，获得若干组不同的外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数和扬声器到反馈麦克风的传递函数。
  7. 如权利要求2至6任一项所述的主动降噪耳机的滤波器设计方法，其特征在于，所述从若干修正后的前馈滤波器的理想频率响应曲线中选择平坦度符合预设要求的修正后的前馈滤波器的理想频率响应曲线，包括：
    从若干修正后的前馈滤波器的理想频率响应曲线中选择在预设频段内的幅度变化量大于第一幅度阈值且小于第二幅度阈值、相位变化量大于第一相位阈值且小于第二相位阈值的修正后的前馈滤波器的理想频率响应曲线；
    或者，从若干修正后的前馈滤波器的理想频率响应曲线中选择在预设频段内的每个预设倍频程理想幅频特性曲线的斜率的绝对值小于幅度变化率阈值、理想相频特性曲线的斜率的绝对值小于相位变化率阈值的修正后的前馈滤波器的理想频率响应曲线；
    其中，所述修正后的前馈滤波器的理想频率响应曲线包括修正后的前馈滤波器的理想幅频特性曲线和理想相频特性曲线。
  8. 如权利要求7所述的主动降噪耳机的滤波器设计方法，其特征在于，所述预设频段为100Hz~300Hz。
  9. 如权利要求7所述的主动降噪耳机的滤波器设计方法，其特征在于，所述第一幅度阈值为在预设频段内的平均幅度值与下限幅度阈值之差，所述第二幅度阈值为预设频段内的平均幅度值与上限幅度阈值之和；
    所述第一相位阈值为在预设频段内的平均相位值与下限相位阈值之差，所述第二相位阈值为预设频段内的平均相位值与上限相位阈值之和。
  10. 如权利要求9所述的主动降噪耳机的滤波器设计方法，其特征在于，所述下限幅度阈值和所述上限幅度阈值都为8分贝。
  11. 如权利要求9所述的主动降噪耳机的滤波器设计方法，其特征在于，所述下限相位阈值和所述上限相位阈值都为30度。
  12. 如权利要求7所述的主动降噪耳机的滤波器设计方法，其特征在于，所述预设倍频程为1/3倍频程。
  13. 如权利要求7所述的主动降噪耳机的滤波器设计方法，其特征在于，所述幅度变化率阈值为4分贝每1/3倍频程。
  14. 如权利要求7所述的主动降噪耳机的滤波器设计方法，其特征在于，所述相位变化率阈值为15度每1/3倍频程。
  15. 如权利要求1至6任一项所述的主动降噪耳机的滤波器设计方法，其特征在于，所述修正后的前馈滤波器的理想频率响应曲线的表达式为：
    Hf _target _new=（Tae/Tde–Hb*Nb*Tab）/（Taf*（1 -Hb*Nb*Tdb））；
    Nb=1/（1+Tdb*Hb）；
    其中，Hf_target _new表示修正后的前馈滤波器的理想频率响应曲线，Hb表示反馈滤波器的频率响应曲线，Tae表示外部噪声到耳道中的标准麦克风的传递函数，Tde表示扬声器到耳道中的标准麦克风的传递函数，Taf 表示外部噪声到前馈麦克风的传递函数，Tab表示外部噪声到反馈麦克风的传递函数，Tdb表示扬声器到反馈麦克风的传递函数，Nb表示通过反馈滤波器进行单独降噪时反馈麦克风处的降噪率。
  16. 如权利要求1至6任一项所述的主动降噪耳机的滤波器设计方法，其特征在于，还包括：
    根据反馈滤波器的频率响应曲线、外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到前馈麦克风的传递函数、外部噪声到反馈麦克风的传递函数、扬声器到反馈麦克风的传递函数及前馈滤波器的实际频率响应曲线，获得修正后的混合降噪效果曲线。
  17. 如权利要求16所述的主动降噪耳机的滤波器设计方法，其特征在于，所述修正后的混合降噪效果曲线的表达式为：
    ANC_hybrid =1-（eb* Hb + Taf*Hf）*Tde/Tae；
    eb=（Tab–Tdb* Hf*Taf）* Nb；
    其中，ANC_hybrid表示修正后的混合降噪效果曲线，Hb表示反馈滤波器的频率响应曲线，Hf表示前馈滤波器的实际频率响应曲线，Tae表示外部噪声到耳道中的标准麦克风的传递函数，Tde表示扬声器到耳道中的标准麦克风的传递函数，Taf 表示外部噪声到前馈麦克风的传递函数，Tab表示外部噪声到反馈麦克风的传递函数，Tdb表示扬声器到反馈麦克风的传递函数，Nb表示通过反馈滤波器进行单独降噪时反馈麦克风处的降噪率，eb表示通过反馈滤波器和前馈滤波器进行混合降噪时反馈麦克风处的噪声。
  18. 如权利要求1至6任一项所述的主动降噪耳机的滤波器设计方法，其特征在于，所述耳道为仿真耳的耳道或人耳的耳道。
  19. 一种主动降噪耳机的滤波器设计装置，其特征在于，包括：
    修正模块，用于根据反馈滤波器的频率响应曲线、外部噪声到耳道中的标准麦克风的传递函数、扬声器到耳道中的标准麦克风的传递函数、外部噪声到反馈麦克风的传递函数及扬声器到反馈麦克风的传递函数，对前馈滤波器的理想频率响应曲线进行修正；
    设计模块，用于根据修正后的前馈滤波器的理想频率响应曲线设计前馈滤波器。
  20. 一种测试设备，包括存储器、处理器以及存储在所述存储器中并可在所述处理器上运行的计算机程序，其特征在于，所述处理器执行所述计算机程序时实现如权利要求1至18任一项所述的主动降噪耳机的滤波器设计方法的步骤。
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