Active noise reduction method for headphones, active noise reduction system and noise reduction headphones

Abstract

The present disclosure relates to an active noise reduction method for headphones, an active noise reduction system and noise reduction headphones. The headphones include a speaker, a feedforward noise reduction path including a feedforward microphone and a feedforward IIR filter group in sequence, and an in-ear microphone. The active noise reduction method includes connecting a feedforward adaptive FIR filter downstream of the feedforward IIR filter group; turning on the feedforward adaptive FIR filter when the external environmental noise is large, calibrating the echo filter parameters downstream of the feedforward adaptive FIR filter, and determining the first filter coefficient for configuring the feedforward adaptive FIR filter based on the first noise signal obtained through the feedforward noise reduction path and the residual noise signal obtained by the in-ear microphone, thereby optimizing the active noise reduction effect. The active noise reduction method disclosed in the present disclosure can adapt to the ear canal shape of each wearer, provide personalized ANC parameters, improve the problem of poor consistency of ANC effect caused by differences in earphone cavities, and skip the production line calibration step to save earphone production costs.

Description

Technical Field

[0001] The present disclosure relates to active noise reduction technology for headphones, and more particularly, to an active noise reduction method for headphones, an active noise reduction system, and noise reduction headphones. Background Art

[0002] With the advancement of society and the improvement of people's living standards, headphones have become an indispensable daily necessity. They provide users with comfortable listening experience in noisy environments such as airports, subways, airplanes, and restaurants, and are therefore increasingly recognized by the market and customers. However, for in-ear and semi-in-ear headphones, different wearing styles (such as wearing tightness and wearing direction) and individual differences in ear canal structure (such as ear canal length, width, and reflection) can significantly affect the headphone's sound field.

[0003] Existing headphone products only have one Active Noise Cancellation (ANC) curve, tuned based on an artificial head, for each model. This curve is used to implement active noise cancellation. However, since each user's ear canal varies greatly, the artificial head's ear canal information cannot accurately reflect the individual's ear canal information. Therefore, the individual ANC experience will differ from that achieved with the artificial head. Furthermore, the calibration process on the production line relies on the accurate placement of the headphone head, and the calibration effect cannot be guaranteed. Consequently, the noise cancellation effect of the same ANC headphone often varies, and uniformly configured headphone parameters may not meet the needs of all individual users, resulting in some users experiencing subpar active noise cancellation. Summary of the Invention

[0004] The present disclosure is provided to solve the above-mentioned problems existing in the prior art.

[0005] What is needed is an active noise reduction method, active noise reduction system and headphones for headphones, which can perform personalized measurement and adaptive compensation of the filter parameters in the echo path and active noise reduction path of the headphones according to the differences in the cavities (microphones, speakers, etc.) of different headphones, differences in the external environment, and differences in wearing methods and ear canals of different users, so that when the external environment noise is large, the headphones can obtain better active noise reduction effects by turning on the personalized active noise reduction function, thereby improving the listening experience of the headphone users.

[0006] According to a first aspect of the present disclosure, a method for active noise reduction for headphones is provided. The headphones include a speaker, a feedforward noise reduction path sequentially including a feedforward microphone and a feedforward IIR filter group, and an in-ear microphone. The method includes connecting a feedforward adaptive FIR filter downstream of the feedforward IIR filter group in the feedforward noise reduction path. The method also includes, when external environmental noise is high, activating the feedforward adaptive FIR filter and adjusting a first filter coefficient of the feedforward adaptive FIR filter until a first noise suppression amount obtained when the feedforward adaptive FIR filter is configured with the adjusted first filter coefficient meets a predetermined condition: configuring an echo filter connected downstream of the feedforward adaptive FIR filter based on a second filter parameter; obtaining a first noise signal obtained by processing an external noise signal collected by the feedforward microphone through the feedforward IIR filter group, the feedforward adaptive FIR filter, and the echo filter, and a residual noise signal collected by the in-ear microphone, and determining the first filter coefficient based on the obtained first noise signal and the residual noise signal.

[0007] According to a second aspect of the present disclosure, an active noise reduction system is provided for use with headphones. The headphones include a speaker, a feedforward noise reduction path sequentially including a feedforward microphone and a feedforward IIR filter group, and an in-ear microphone. A feedforward adaptive FIR filter is connected downstream of the feedforward IIR filter group in the feedforward noise reduction path. The active noise reduction system also includes a processor configured to: when external environmental noise is large, enable the feedforward adaptive FIR filter and adjust a first filter coefficient of the feedforward adaptive FIR filter by performing the following steps until a first noise suppression amount obtained when the feedforward adaptive FIR filter is configured with the adjusted first filter coefficient meets a predetermined condition: configuring an echo filter connected downstream of the feedforward adaptive FIR filter based on a second filter parameter; obtaining a first noise signal obtained by processing an external noise signal collected by the feedforward microphone through the feedforward IIR filter group, the feedforward adaptive FIR filter, and the echo filter, and a residual noise signal collected by the in-ear microphone, and determining the first filter coefficient based on the obtained first noise signal and the residual noise signal.

[0008] According to a third aspect of the present disclosure, a noise-canceling headset is provided, comprising a speaker, a feedforward noise reduction path sequentially comprising a feedforward microphone and a feedforward IIR filter group, and an in-ear microphone, wherein a feedforward adaptive FIR filter is connected downstream of the feedforward IIR filter group in the feedforward noise reduction path. The noise-canceling headset also includes a memory and a processor, wherein the memory stores computer-executable instructions that, when executed by the processor, implement the various steps of the active noise reduction method according to various embodiments of the present disclosure.

[0009] By utilizing the various active noise reduction methods, active noise reduction systems and noise reduction headphones for headphones disclosed in the present invention, not only can the echo path be personalized measured and parameter configuration be performed when the user wears headphones, but also, when the external environmental noise is large, based on the external noise signal collected in real time by the external ear microphone and the residual noise signal leaked into the ear collected in real time by the in-ear microphone, the first filter coefficient can be adaptively determined to configure a feedforward adaptive FIR filter, and the ideal first filter coefficient can be selected according to the noise suppression amount before and after the feedforward adaptive FIR filter is turned on, to ensure that the headphones obtain an optimized active noise reduction effect. In this way, the active noise reduction method according to the present invention can not only better adapt to the ear canal shape of each headphone wearer and configure suitable and ideal personalized ANC parameters for each user, but also automatically compensate for the problem of poor consistency of ANC effects caused by differences in headphone cavities. The effect is better than production line calibration, and the production line calibration step can be skipped, saving manpower and time costs in headphone production. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In the drawings, which are not necessarily drawn to scale, the same reference numerals may describe similar components in different views. The same reference numerals with letter suffixes or different letter suffixes may represent different instances of similar components. The accompanying drawings generally illustrate various embodiments by way of example and not limitation, and together with the description and claims, serve to illustrate the disclosed embodiments. Where appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive of the embodiments of the present apparatus or method.

[0011] Figure 1 A flow chart showing an active noise reduction method for headphones according to an embodiment of the present disclosure is shown;

[0012] Figure 2 A second filter parameter determination flow chart of the active noise reduction method for headphones according to an embodiment of the present disclosure is shown;

[0013] Figure 3 A principle block diagram of a first filter coefficient calculation method according to an embodiment of the present disclosure is shown;

[0014] Figure 4 A flowchart of another first filter coefficient calculation method according to an embodiment of the present disclosure is shown;

[0015] Figure 5 A schematic structural diagram of an active noise reduction system according to an embodiment of the present disclosure is shown;

[0016] Figure 6 Another structural diagram of the active noise reduction system according to an embodiment of the present disclosure is shown; and

[0017] Figure 7 A schematic structural diagram of an earphone according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the present disclosure is described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments of the present disclosure are further described in detail below in conjunction with the accompanying drawings and specific embodiments, but are not intended to limit the present disclosure.

[0019] Figure 1 FIG. 1 is a flow chart showing an active noise reduction method for headphones according to an embodiment of the present disclosure. Figure 1 As shown, an active noise reduction method for headphones, the headphones include a speaker, a feedforward noise reduction path including a feedforward microphone and a feedforward IIR filter group in sequence, and an in-ear microphone. The active noise reduction method begins in step S100, and a feedforward adaptive FIR filter is connected to the downstream of the feedforward IIR filter group on the feedforward noise reduction path. The feedforward microphone is used to collect external noise signals from the external environment, and the collected external noise signals can be processed by the feedforward IIR filter group and the feedforward adaptive FIR filter in sequence. The in-ear microphone is used to collect residual noise signals leaked from the noise signals in the external environment into the ear, and the second bandpass filter is used to filter and process the residual noise signals.

[0020] In step S200, if the external environmental noise is high, the feedforward adaptive FIR filter can be activated. In some embodiments, the first filter coefficient of the feedforward adaptive FIR filter can be adjusted by repeatedly performing steps S300-S500 until the first noise suppression amount obtained when the feedforward adaptive FIR filter is configured with the adjusted first filter coefficient meets a predetermined condition. It should be noted that the "high external environmental noise" referred to herein can be determined based on the intensity of the external noise signal in the external environment captured by the feedforward microphone, or based on the subjective experience of the headphone user. By way of example only, if the intensity of the external noise signal in the external environment captured by the feedforward microphone is greater than 30-50 decibels, it is determined that the external environmental noise is high, and the feedforward adaptive FIR filter can be activated. Since the feedforward adaptive FIR filter is only activated when the external environmental noise is high, the operating power consumption of the active noise reduction method can be effectively reduced.

[0021] In step S300, the echo filter connected to the downstream of the feedforward adaptive FIR filter can be configured based on the second filtering parameters. In some embodiments, the echo path estimation information obtained based on the configuration on the artificial head or the preset parameters of the echo filter can be used as the second filtering parameters. In other embodiments, considering that the parameter information of the echo path may vary greatly depending on the user during the use of the headset, the headset may not estimate the parameters of the echo path or the preset parameter information of the echo filter through the artificial head before leaving the factory. Instead, the second filtering parameters can be tested while the user is wearing the headset and actually using it. In this way, not only can the process of factory testing of the headset be saved, but a more accurate configuration of the echo filter can also be obtained. In this case, the specific method for determining the second filtering parameters will be described below in conjunction with Figure 2 Provide a detailed description.

[0022] Then, in step S400, a first noise signal obtained after the external noise signal collected by the feedforward microphone is processed by the feedforward IIR filter group, the feedforward adaptive FIR filter, and the echo filter, as well as a residual noise signal collected by the in-ear microphone can be obtained, and the first filter coefficient is determined based on the obtained first noise signal and the residual noise signal, and the feedforward adaptive FIR filter is configured with the first filter coefficient.

[0023] Next, in step S500, the first noise suppression amount can be calculated, and it can be determined whether the first noise suppression amount meets the predetermined condition. If the first noise suppression amount fails to meet the predetermined condition, the process returns to step S300 and continues to adjust the first filter coefficient. If the first noise suppression amount has reached the predetermined condition, the adjustment of the first filter coefficient is terminated.

[0024] The active noise reduction method according to an embodiment of the present disclosure further includes: playing a first audio reference signal by the speaker; and determining a second filtering parameter of the echo filter based on a first audio signal obtained by collecting the first audio reference signal by the in-ear microphone and the first audio reference signal. Figure 2 FIG. 2 shows a second filter parameter determination flow chart of the active noise reduction method for headphones according to an embodiment of the present disclosure. Figure 2 As shown, in some embodiments, when a user wears headphones normally, a first audio reference signal 202 can be played by a speaker 201. The first audio reference signal 202 can first be fed to a first N-fold downsampling filter 203 for N-fold downsampling processing, and then the downsampled first audio reference signal 202' is fed to a second filter parameter calculation unit 204. Simultaneously, after the first audio reference signal 202 is reflected by the ear canal, it can be collected by an in-ear microphone 205 to obtain a first audio signal 206. Similarly, the first audio signal 206 is first fed to a second N-fold downsampling filter 207, and after N-fold downsampling processing, the downsampled first audio signal 206' is fed to the second filter parameter calculation unit 204. Then, the second filter parameter calculation unit 204 determines the second filter parameters based on the downsampled first audio reference signal 202' and the downsampled first audio signal 206', and uses the second filter parameters to configure the echo filter 208. The echo filter 208 is set in the headphone feedforward noise reduction path to fit the transfer function from the speaker to the ear canal. Figure 2 The method shown here allows the same earphones to be compatible with different ear canal structures, eliminating the problem of poor listening experience caused by different ear canal structures. It also allows different users to get a customized ANC experience tailored to their ear canals, achieving better cavity calibration than on a production line, saving labor and time costs in headphone production.

[0025] In other embodiments, the above-described processes are not limited to the case where the user wears headphones, but can also be implemented when the headphones are placed on an artificial head, and the measured echo path estimation information or preset parameters of the echo filter can be used as the second filtering parameters.

[0026] In some embodiments, the active noise reduction method according to an embodiment of the present disclosure further includes, before playing the first audio reference signal, having the speaker play a prompt signal indicating that a measurement is about to begin. By way of example only, the prompt signal indicating that the measurement is about to begin includes, among other things, a reminder that the measurement is about to begin and measurement operation precautions. For example, the prompt indicating that the measurement is about to begin may include "Headphone calibration will begin in N seconds," where N can be 2, 3, or 5, among other things. The measurement operation precautions may include a reminder to the user not to talk or shake their head during the test to avoid interfering with the test process.

[0027] Figure 3 FIG. 1 shows a principle block diagram of a first filter coefficient calculation method according to an embodiment of the present disclosure. Figure 3 As shown, the feedforward microphone 301 and the in-ear microphone 308 are respectively connected to a first N-fold downsampling filter 303 and a second N-fold downsampling filter 310. In some embodiments, the external noise signal 302 collected by the feedforward microphone 301 is downsampled N-fold by the first N-fold downsampling filter 303, fed to the feedforward IIR filter bank 304 for filtering, and then fed to the feedforward adaptive FIR filter 305 for adaptive filtering. One branch is output from the speaker 312, and the other branch is fed to the echo filter 306 for echo filtering. The resulting first noise signal 311 is finally fed to the computing unit 307. In the other branch, the residual noise signal 309 collected by the in-ear microphone 308 is downsampled N-fold by the second N-fold downsampling filter 310, and the downsampled residual noise signal 309' is fed to the computing unit 307. The calculation unit 307 determines the first filter coefficient according to the first noise signal 311 and the down-sampled residual noise signal 309 ′, and uses the first filter coefficient for configuring the feedforward adaptive FIR filter 305 .

[0028] In some embodiments, when the first filter coefficient configures the feedforward adaptive FIR filter 305, the first noise suppression amount calculated based on the external noise signal 302 and the residual noise signal 309 can be repeated again if it is determined that the first noise suppression amount does not meet the predetermined condition. Figure 2 and / or Figure 3 The processing flow shown in FIG. 1 is to control the feedforward microphone 301 to re-collect the external noise signal 302 and the in-ear microphone 308 to re-collect the residual noise signal 309, and calculate the first filter coefficient until the first noise suppression amount obtained when the feedforward adaptive FIR filter 305 is configured with the first filter coefficient reaches a predetermined condition.

[0029] In some embodiments, determining whether the first noise suppression amount meets the predetermined condition can be based on different criteria, including but not limited to obtaining the second noise suppression amount obtained when the feedforward adaptive FIR filter is turned off. When the first noise suppression amount is greater than the second noise suppression amount, it is determined that the first noise suppression amount has met the predetermined condition. In other embodiments, it is also possible to determine whether the first noise suppression amount has reached a first noise reduction threshold. As an example only, the first noise reduction threshold can be a pre-set value such as approximately -40dB. When the first noise suppression amount reaches the first noise reduction threshold, it can be determined that the first noise suppression amount has met the predetermined condition. In other embodiments, it is also possible to determine that the first noise suppression amount has met the predetermined condition by the user of the headset giving an indication of achieving the expected noise reduction effect based on subjective feelings.

[0030] Therefore, when the feedforward adaptive FIR filter is configured using the finally determined first filtering parameters, it can not only effectively shield external noise, but also adapt to the user's different ear canal structures and different wearing methods, providing the user with a good listening experience.

[0031] In some embodiments, a first band-pass filter may be connected downstream of the echo filter, and a second band-pass filter may be connected downstream of the in-ear microphone. In this case, obtaining a first noise signal obtained after processing the external noise signal collected by the feedforward microphone through the feedforward IIR filter group, the feedforward adaptive FIR filter, and the echo filter, and a residual noise signal collected by the in-ear microphone, and determining the first filter coefficient based on the obtained first noise signal and the residual noise signal may further include: obtaining the first noise signal processed by the first band-pass filter and the residual noise signal processed by the second band-pass filter, and determining the first filter coefficient based on the first noise signal after band-pass filtering and the residual noise signal after band-pass filtering.

[0032] Figure 4 FIG. 1 shows a principle block diagram of another first filter coefficient calculation method according to an embodiment of the present disclosure. Figure 4As shown, a first band-pass filter 412 may be connected downstream of the echo filter 406, and a second band-pass filter 413 may be connected downstream of the in-ear microphone 408. In this way, the external noise signal 402 collected by the feedforward microphone 401 is subjected to N-fold downsampling processing by the first N-fold downsampling filter 403, and then fed to the feedforward IIR filter group 404 for filtering processing, and then fed to the feedforward adaptive FIR filter 405 for adaptive filtering processing. One path is output from the speaker 414, and the other path is fed to the echo filter 406 for echo filtering processing to obtain a first noise signal 411. Finally, the first noise signal 411 is band-pass filtered by the first band-pass filter 412, and the first noise signal 411' after band-pass filtering is fed to the calculation unit 407. In another branch, the residual noise signal 409 collected by the in-ear microphone 408 is subjected to N-fold downsampling processing by the second N-fold downsampling filter 410, and then subjected to bandpass filtering processing by the second bandpass filter 413, and the residual noise signal 409' after bandpass filtering is fed to the calculation unit 407. The calculation unit 407 determines the first filter coefficient based on the first noise signal 411' after bandpass filtering and the residual noise signal 409' after bandpass filtering, and uses the first filter coefficient to configure the feedforward adaptive FIR filter 405. Combined with the above Figure 3 The described process is similar. In this example, when the feedforward adaptive FIR filter 405 is configured using the first filter coefficient, the first noise suppression amount calculated based on the external noise signal 402 and the residual noise signal 409 will also be used, and whether the iterative calculation of the first filter coefficient is stopped will be controlled based on whether the first noise suppression amount meets the predetermined conditions.

[0033] like Figure 4 The calculation method and processing flow of the first filter coefficient shown, since the noise signals in both branches are band-pass filtered, can be used to optimize the noise reduction effect for a specific noise reduction frequency band of interest in some embodiments, and can filter out signals in frequency bands that are not of interest, thereby reducing the impact of interference signals in other frequency bands outside the frequency band of interest. Exemplarily, the first band-pass filter 412 and the second band-pass filter 413 can select mid-to-high frequency bands, thereby focusing the optimization of the noise reduction effect on the mid-to-high frequency bands that are more affected by the individual ear canal, so that the active noise reduction of the headphones can better adapt to the shape of each person's ear canal. In some embodiments, the first band-pass filter 412 and the second band-pass filter 413 can, for example, select a frequency band from 800 Hz to 1.2 kHz. As an example, the passband can be set to 800 Hz, 900 Hz, 1.0 kHz, 1.1 kHz, 1.2 kHz, etc., and the embodiments of the present disclosure do not impose specific restrictions on this.

[0034] In some embodiments, for example, Figure 4 In the first filter coefficient calculation method shown, determining the first filter coefficient based on the first noise signal after bandpass filtering and the residual noise signal after bandpass filtering specifically includes iterating through the following formula (1-1) and formula (1-2) to determine the first filter coefficient:

[0035] d(n)=[d0(n),d1(n),…,d L-1 (n)] T Formula (1-1)

[0036]

[0037] Wherein, L is the length of the feedforward adaptive FIR filter 405, d(n)=[d0(n), d1(n), ..., d L-1 (n)] T is the first filter coefficient at time n, δ is the adjustment step size of the feedforward adaptive FIR filter 405, C(n) represents the first noise signal 411′ after bandpass filtering, and C(n)=[c(n), c(n-1), ..., c(n-L+1)] T , r(n) is the residual noise signal 409' after bandpass filtering, and d(n+1) is the first filter coefficient at time n+1.

[0038] Figure 5 FIG. 1 shows a schematic structural diagram of an active noise reduction system according to an embodiment of the present disclosure. Figure 5As shown, the embodiment of the present disclosure also provides an active noise reduction system 500. The active noise reduction system 500 is applied to headphones 510, and the headphones 510 include a speaker 511, a feedforward noise reduction path including a feedforward microphone 512 and a feedforward IIR filter group 513 in sequence, and an in-ear microphone 514. A feedforward adaptive FIR filter 515 is connected downstream of the feedforward IIR filter group 513 on the feedforward noise reduction path. The active noise reduction system 500 also includes a processor 501, and the processor 501 is configured to: when the external environmental noise is large, turn on the feedforward adaptive FIR filter, and adjust the first step of the feedforward adaptive FIR filter through the following steps. a filter coefficient, until a first noise suppression amount obtained when the feedforward adaptive FIR filter is configured with the adjusted first filter coefficient reaches a predetermined condition; configuring an echo filter connected downstream of the feedforward adaptive FIR filter based on the second filter parameter; obtaining a first noise signal obtained after processing the external noise signal collected by the feedforward microphone through the feedforward IIR filter group, the feedforward adaptive FIR filter, and the echo filter, and a residual noise signal collected by the in-ear microphone, and determining the first filter coefficient based on the obtained first noise signal and the residual noise signal.

[0039] The processor 501 may be a processing device including one or more general-purpose processing devices, such as a microprocessor, a central processing unit (CPU), a graphics processing unit (GPU), and the like. More specifically, the processor 501 may be a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a processor that runs other instruction sets, or a processor that runs a combination of instruction sets. The processor 501 may also be one or more special-purpose processing devices, such as an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), a system on a chip (SoC), and the like. The processor 501 may be communicatively coupled to a memory and configured to execute computer-executable instructions stored thereon to execute the headphone control method of the above-mentioned embodiment. The equalization control unit according to various embodiments of the present disclosure may be implemented as software, as hardware, or as a combination of software and hardware.

[0040] Figure 6 Another structural diagram of the active noise reduction system according to an embodiment of the present disclosure is shown. Figure 6In the active noise reduction system 600 shown, a first bandpass filter 517 is connected downstream of the echo filter 516, and a second bandpass filter 518 is connected downstream of the in-ear microphone 514. The processor 501 is further configured to: obtain a first noise signal processed by the first bandpass filter 517 and a residual noise signal processed by the second bandpass filter 518, and determine the first filter coefficient based on the first noise signal after bandpass filtering and the residual noise signal after bandpass filtering.

[0041] In some embodiments, the processor 501 can be further configured to: obtain a second noise suppression amount obtained when the feedforward adaptive FIR filter 515 is turned off, wherein the predetermined condition of the first noise suppression amount may include the first noise suppression amount being greater than the second noise suppression amount, or the first noise suppression amount reaching a first noise reduction threshold, or the user of the headset 510 indicating that the expected noise reduction effect is achieved.

[0042] In some embodiments, the processor 501 is further configured to: use the echo path estimation information obtained based on the configuration on the artificial head or the preset parameters of the echo filter 516 as the second filtering parameters, or control the speaker 511 to play the first audio reference signal; determine the second filtering parameters of the echo filter 516 based on the first audio signal obtained by the in-ear microphone 514 collecting the first audio reference signal and the first audio reference signal.

[0043] Figure 7 FIG. 1 shows a schematic diagram of the structure of an earphone according to an embodiment of the present disclosure. Figure 7 As shown, embodiments of the present disclosure also provide noise-canceling headphones. The noise-canceling headphones 700 include a speaker 701, a feedforward noise reduction path sequentially including a feedforward microphone 702 and a feedforward IIR filter bank 703, and an in-ear microphone 704. A feedforward adaptive FIR filter 705 is connected downstream of the feedforward IIR filter bank 703 in the feedforward noise reduction path. The noise-canceling headphones also include a memory 707 and a processor 708. The memory 707 stores computer-executable instructions that, when executed by the processor 708, implement the various steps of the active noise reduction method described in various embodiments of the present disclosure. In some embodiments, the noise-canceling headphones 700 may further include an echo filter 706 connected downstream of the feedforward adaptive FIR filter 705. The echo filter 706 can be used by the processor 708 to perform the steps corresponding to adjusting the first filter coefficient of the feedforward adaptive FIR filter in the active noise reduction method described in various embodiments of the present disclosure.

[0044] Furthermore, although exemplary embodiments have been described herein, the scope includes any and all embodiments based on the present disclosure with equivalent elements, modifications, omissions, combinations (e.g., solutions that intersect various embodiments), adaptations, or changes. The elements in the claims are to be interpreted broadly based on the language employed in the claims and are not limited to the examples described in this specification or during the prosecution of this application, which examples are to be interpreted as non-exclusive. Therefore, this specification and examples are intended to be considered as examples only, with the true scope and spirit being indicated by the following claims and the full scope of their equivalents.

[0045] The above description is intended to be illustrative and not restrictive. For example, the above examples (or one or more schemes thereof) can be used in combination with each other. For example, a person of ordinary skill in the art may use other embodiments when reading the above description. In addition, in the above-mentioned specific embodiments, various features can be grouped together to simplify the present disclosure. This should not be interpreted as an intention that a disclosed feature that is not required to be protected is necessary for any claim. On the contrary, the subject matter of the present invention may be less than all the features of a specific disclosed embodiment. Thus, the following claims are incorporated into the specific embodiments as examples or embodiments, wherein each claim is independently a separate embodiment, and it is considered that these embodiments can be combined with each other in various combinations or arrangements. The scope of the present invention should be determined with reference to the appended claims and the full scope of equivalents to which these claims are entitled.

Claims

1. An active noise reduction method for headphones, the headphones comprising a speaker, a feedforward noise reduction path comprising a feedforward microphone and a feedforward IIR filter bank in sequence, and an in-ear microphone, characterized in that: The active noise reduction method comprises: A feedforward adaptive FIR filter is connected downstream of the feedforward IIR filter group on the feedforward noise reduction path, an echo filter is connected downstream of the feedforward adaptive FIR filter, a first bandpass filter is connected downstream of the echo filter, and a second bandpass filter is connected downstream of the in-ear microphone, wherein the first bandpass filter and the second bandpass filter are selected in the frequency range of 800 Hz to 1.2 kHz; When the external environment noise is large, the feedforward adaptive FIR filter is turned on, and the first filter coefficient of the feedforward adaptive FIR filter is adjusted through the following steps until a first noise suppression amount obtained when the feedforward adaptive FIR filter is configured with the adjusted first filter coefficient reaches a predetermined condition: Configuring the echo filter based on the second filtering parameters, wherein the second filtering parameters of the echo filter are not estimated using an artificial head before the earphones leave the factory, but rather the second filtering parameters of the echo filter are obtained when the user wears the earphones and actually uses the earphones; Obtain a first noise signal obtained by processing the external noise signal collected by the feedforward microphone through the feedforward IIR filter group, the feedforward adaptive FIR filter, the echo filter, and the first bandpass filter, and obtain a residual noise signal collected by the in-ear microphone and processed by the second bandpass filter, and determine the first filter coefficient based on the first noise signal after bandpass filtering and the residual noise signal after bandpass filtering.

2. The active noise reduction method according to claim 1, wherein: The active noise reduction method further includes: obtaining a second noise suppression amount obtained when the feedforward adaptive FIR filter is turned off; The predetermined condition of the first noise suppression amount includes: the first noise suppression amount is greater than the second noise suppression amount, or The first noise suppression amount reaches a first noise reduction threshold, or The user of the headset indicates that the expected noise reduction effect is achieved.

3. The active noise reduction method according to claim 1, wherein: The active noise reduction method further includes: Playing a first audio reference signal through the speaker; A second filtering parameter of the echo filter is determined based on a first audio signal obtained by collecting a first audio reference signal by the in-ear microphone and the first audio reference signal.

4. The active noise reduction method according to claim 3, characterized in that: The active noise reduction method further includes: Before playing the first audio reference signal, the speaker plays a prompt signal indicating that measurement is about to start.

5. The active noise reduction method according to claim 1, wherein: Determining the first filter coefficient based on the first noise signal after bandpass filtering and the residual noise signal after bandpass filtering specifically includes iterating through the following formula (1-1) and formula (1-2) to determine the first filter coefficient: d(n)=[d0(n),d1(n),…,d L-1 (n)] T Formula (1-1) Where L is the length of the feedforward adaptive FIR filter, d(n) = [d0(n), d1(n), ..., d L-1 (n)] T is the first filter coefficient at time n, δ is the adjustment step size of the feedforward adaptive FIR filter, C(n) represents the first noise signal after bandpass filtering, C(n) = [c(n), c(n-1), ..., c(n-L+1)] T , r(n) is the residual noise signal after bandpass filtering, and d(n+1) is the first filter coefficient at time n+1.

6. An active noise reduction system for headphones, the headphones comprising a speaker, a feedforward noise reduction path comprising a feedforward microphone and a feedforward IIR filter bank in sequence, and an in-ear microphone, characterized in that: A feedforward adaptive FIR filter is connected downstream of the feedforward IIR filter group in the feedforward noise reduction path, an echo filter is connected downstream of the feedforward adaptive FIR filter, a first bandpass filter is connected downstream of the echo filter, and a second bandpass filter is connected downstream of the in-ear microphone, wherein the first bandpass filter and the second bandpass filter select a frequency band of 800 Hz to 1.2 kHz. The active noise reduction system further includes a processor, which is configured to: When the external environment noise is large, the feedforward adaptive FIR filter is turned on, and the first filter coefficient of the feedforward adaptive FIR filter is adjusted through the following steps until a first noise suppression amount obtained when the feedforward adaptive FIR filter is configured with the adjusted first filter coefficient reaches a predetermined condition: Configuring the echo filter based on the second filtering parameters, wherein the second filtering parameters of the echo filter are not estimated using an artificial head before the earphones leave the factory, but rather the second filtering parameters of the echo filter are obtained when the user wears the earphones and actually uses the earphones; Obtain a first noise signal obtained by processing the external noise signal collected by the feedforward microphone through the feedforward IIR filter group, the feedforward adaptive FIR filter, the echo filter, and the first bandpass filter, and obtain a residual noise signal collected by the in-ear microphone and processed by the second bandpass filter, and determine the first filter coefficient based on the first noise signal after bandpass filtering and the residual noise signal after bandpass filtering.

7. The active noise reduction system according to claim 6, characterized in that: The processor is further configured to: Obtaining a second noise suppression amount obtained when the feedforward adaptive FIR filter is turned off; The predetermined condition of the first noise suppression amount includes: the first noise suppression amount is greater than the second noise suppression amount, or The first noise suppression amount reaches a first noise reduction threshold, or The user of the headset indicates that the expected noise reduction effect is achieved.

8. The active noise reduction system according to claim 6, characterized in that: The processor is further configured to: controlling the speaker to play a first audio reference signal; A second filtering parameter of the echo filter is determined based on a first audio signal obtained by collecting a first audio reference signal by the in-ear microphone and the first audio reference signal.

9. A noise-canceling headset comprising a speaker, a feedforward noise reduction path comprising a feedforward microphone and a feedforward IIR filter bank in sequence, and an in-ear microphone, wherein: A feedforward adaptive FIR filter is connected downstream of the feedforward IIR filter group in the feedforward noise reduction path, an echo filter is connected downstream of the feedforward adaptive FIR filter, a first bandpass filter is connected downstream of the echo filter, and a second bandpass filter is connected downstream of the in-ear microphone, wherein the first bandpass filter and the second bandpass filter select a frequency band of 800 Hz to 1.2 kHz. The noise reduction headphones also include a memory and a processor, wherein the memory stores computer-executable instructions, which, when executed by the processor, implement the active noise reduction method according to any one of claims 1 to 5.

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