Active noise reduction earphone
By introducing active noise reduction technology into the headphones and updating the filter coefficients using the adaptive control module, the problem of poor noise reduction in passive noise reduction in noisy environments is solved, better noise reduction in medium and low frequency noise and individual adaptability are achieved, and user experience is improved.
Patent Information
- Application Number
- CN202311562060.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-22
- Publication Date
- 2025-05-23
AI Technical Summary
Existing passive noise reduction headphones have poor noise reduction effects on medium and low frequency noise in noisy environments, and are difficult to adapt to individual differences, resulting in unsatisfactory noise reduction effect.
Active noise reduction technology is adopted to collect feedforward sound signals through feedforward noise reduction channels, and the filter coefficients of the feedforward noise reduction filter are updated through an adaptive algorithm, and the forward noise signal is output to superimpose them to adaptively cancel the noise signal.
It improves the noise reduction effect of headphones on medium and low frequency noise, enhances adaptability to different users, and significantly improves the user experience.
Smart Images
Figure CN120034769A_ABST
Abstract
Description
Technical Field
[0001] The embodiments of the present application relate to the field of electronic technology, and in particular to an active noise reduction headset. Background Art
[0002] With the progress of society and the improvement of people's living standards, headphones have become an indispensable daily necessity. Ordinary Bluetooth headphones cancel the connection between the headphones and the wireless host, but there is still a connection between the left and right ears. In view of this, true wireless stereo headphones without traditional connection cables came into being.
[0003] In the related art, the passive noise reduction method mainly reduces noise interference passively through physical isolation or thickening of sound insulation materials. This method has a better effect on high-frequency noise processing and can isolate most high-frequency noise, so it is suitable for use in a relatively quiet environment. However, when the surrounding environment becomes noisy, the passive noise reduction method has a poor noise reduction effect on medium and low frequency noise. In addition, due to the individual differences in human body characteristics, the passive noise reduction method with a single functional structure is difficult to adapt to everyone. Therefore, for different users, this method is also difficult to achieve the ideal noise reduction effect, resulting in poor noise reduction effect. Summary of the invention
[0004] The embodiment of the present application provides an active noise reduction headset, which is used to improve the noise reduction effect of the headset and enhance the user experience.
[0005] On the one hand, an embodiment of the present application provides an active noise reduction headset, comprising:
[0006] A feedforward noise reduction channel, an adaptive control module, a first superposition module and a playback module, wherein the feedforward noise reduction channel includes: a feedforward acquisition module, a feedforward conversion module and a feedforward noise reduction filter;
[0007] The feedforward acquisition module is used to collect the feedforward sound signal and transmit the feedforward sound signal to the feedforward conversion module;
[0008] The adaptive control module is used to update the filter coefficient of the feedforward noise reduction filter through an adaptive algorithm based on the error signal and the first conversion signal output by the feedforward conversion module;
[0009] The feedforward noise reduction filter is used to filter the first conversion signal based on the updated filter coefficient and output a forward noise signal;
[0010] The first superposition module is used to superimpose the forward noise signal and the audio signal to be played and transmit the superposition signals to the playing module for playing.
[0011] Optionally, the active noise reduction headset further includes: a feedback noise reduction channel; the feedback noise reduction channel includes: a feedback collection module, a feedback conversion module, and a feedback noise reduction filter;
[0012] The feedback collection module is used to collect feedback sound signals and transmit the feedback sound signals to the feedback conversion module;
[0013] The feedback noise reduction filter is used to filter the second conversion signal output by the feedback conversion module and output the reverse noise signal;
[0014] The first superposition module is used to superimpose the forward noise signal, the reverse noise signal, and the audio signal to be played, and then transmit them to the playing module for playing.
[0015] Optionally, the active noise reduction headset further includes: an echo module; the feedback noise reduction channel further includes: a second superposition module;
[0016] The second superposition module is used to superimpose the second conversion signal output by the feedback conversion module and the audio component of the to-be-played audio signal output by the echo module to obtain an ambient noise signal.
[0017] The feedback noise reduction filter is used to filter the environmental noise signal and output the reverse noise signal.
[0018] Optionally, the adaptive control module includes: a first low-pass filtering and down-sampling module, an Sz filter, and an adaptive module; the filter coefficient of the Sz filter corresponds to: a transfer function between the playback input signal of the playback module and the feedback sound signal collected by the feedback collection module; the active noise reduction headset also includes: a second low-pass filtering and down-sampling module;
[0019] The first low-pass filtering and down-sampling module and the Sz filter sequentially process the first conversion signal of the first sampling rate and output an adaptive input signal of a second sampling rate, wherein the second sampling rate is less than the first sampling rate;
[0020] The second low-pass filtering and down-sampling module is used to process the error signal of the first sampling rate and output an adaptive error signal of the second sampling rate;
[0021] The adaptive module is used to update the filter coefficients of the reference filter operating at the second sampling rate through an adaptive algorithm based on the adaptive input signal and the adaptive error signal; and to update the filter coefficients of the feedforward denoising filter operating at the first sampling rate through the filter coefficients of the reference filter.
[0022] Optionally, the ratio of the first sampling rate to the second sampling rate is N, where N is a positive integer greater than 1;
[0023] For n coefficients in the filter coefficients of the reference filter, the adaptive module performs the following operations respectively: configuring the i*N+1th coefficient in the filter coefficients of the feedforward denoising filter as the ith coefficient in the filter coefficients of the reference filter, where i is a positive integer less than or equal to n;
[0024] The adaptive module is further used to set other coefficients in the filter coefficients of the feedforward denoising filter to zero.
[0025] Optionally, the adaptive control module further comprises: a feedback closed-loop filter, wherein the filter coefficient of the feedback closed-loop filter is determined based on the filter coefficient of the feedback noise reduction filter and the filter coefficient of the Sz filter;
[0026] The first low-pass filtering and down-sampling module, the Sz filter and the feedback closed-loop filter sequentially process the first conversion signal of the first sampling rate and output an adaptive input signal of the second sampling rate.
[0027] Optionally, the adaptive control module further includes: a first low-pass filter; the active noise reduction headset further includes: a second low-pass filter;
[0028] The first low-pass filtering and down-sampling module, the Sz filter, the first low-pass filter and the feedback closed-loop filter sequentially process the first conversion signal of the first sampling rate and output an adaptive input signal of the second sampling rate;
[0029] The second low-pass filtering and down-sampling module and the second low-pass filter process the error signal of the first sampling rate in sequence and output an adaptive error signal of the second sampling rate.
[0030] Optionally, the feedforward noise reduction filter comprises:
[0031] A non-recursive filter and a group of recursive filters, wherein the non-recursive filter and the group of recursive filters are connected in series or in parallel, the non-recursive filter is an adaptive filter, and the recursive filter is a filter with fixed coefficients.
[0032] Optionally, the fixed coefficients corresponding to the set of recursive filters are selected from a plurality of preset sets of filter coefficients based on the transfer function of the Sz filter of the active noise reduction headphones, and the transfer function of the Sz filter refers to: the transfer function between the playback input signal of the playback module and the feedback sound signal.
[0033] Optionally, after the adaptive control module updates the filter coefficients of the feedforward noise reduction filter, if the change value of the transfer function of the Sz filter is greater than a preset threshold, the adaptive control module adaptively updates the filter coefficients of the feedforward noise reduction filter again.
[0034] In an embodiment of the present application, the adaptive control module updates the filter coefficient of the feedforward noise reduction filter through an adaptive algorithm based on the error signal and the first conversion signal output by the feedforward conversion module, so that the filter coefficient of the updated feedforward noise reduction filter is more matched with the current noise scene. Therefore, when the feedforward noise reduction filter filters the first conversion signal based on the updated filter coefficient, the output forward noise signal for noise reduction is also more matched with the current noise scene. Then, after the first superposition module superimposes the forward noise signal with the audio signal to be played, it can adaptively offset the noise signal mixed in the audio signal to be played, thereby achieving a good noise reduction effect, thereby reducing the noise heard by the user's ears and improving the user's experience. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.
[0036] Figure 1 A schematic diagram of the structure of an active noise reduction headset provided in an embodiment of the present application;
[0037] Figure 2 A schematic diagram of the structure of an active noise reduction headset provided in an embodiment of the present application;
[0038] Figure 3 A schematic diagram of the structure of an active noise reduction headset provided in an embodiment of the present application;
[0039] Figure 4 A schematic diagram of the structure of an active noise reduction headset provided in an embodiment of the present application;
[0040] Figure 5 A schematic diagram of the structure of an active noise reduction headset provided in an embodiment of the present application;
[0041] Figure 6 A schematic diagram of the structure of an active noise reduction headset provided in an embodiment of the present application;
[0042] Figure 7 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION
[0043] In order to make the purpose, technical solution and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.
[0044] For ease of understanding, the terms involved in the embodiments of the present invention are explained below.
[0045] Active noise reduction: The headphones actively emit sound waves with opposite phases to cancel the sound waves from the feedforward microphone (feedforward), or add a feedback acoustic path to the sound path (feedback) to reduce the noise heard by the ears.
[0046] Under the relevant technology, noise-cancelling headphones generally adopt a passive noise-cancelling method to passively reduce noise interference. However, when the surrounding environment becomes noisy, the passive noise-cancelling method has a poor noise-cancelling effect on mid- and low-frequency noise. Moreover, for different users, noise-cancelling headphones using a passive noise-cancelling method are difficult to achieve an ideal noise-cancelling effect, resulting in a poor noise-cancelling experience.
[0047] In view of this, reference Figure 1 , which is a schematic diagram of the structure of an active noise reduction headset provided by the present application, the active noise reduction headset 100 includes:
[0048] The feedforward noise reduction channel 101 , the adaptive control module 102 , the first superposition module 103 and the playback module 104 , the feedforward noise reduction channel 101 includes: a feedforward acquisition module 1011 , a feedforward conversion module 1012 and a feedforward noise reduction filter 1013 .
[0049] The feedforward acquisition module 101 is used to collect the feedforward sound signal and transmit the feedforward sound signal to the feedforward conversion module 1011. The adaptive control module 102 is used to update the filter coefficient of the feedforward noise reduction filter 1013 through an adaptive algorithm based on the error signal and the first conversion signal output by the feedforward conversion module 1012; the feedforward noise reduction filter 1013 is used to filter the first conversion signal based on the updated filter coefficient and output a forward noise signal; the first superposition module 103 is used to superimpose the forward noise signal with the audio signal to be played and transmit it to the playback module 104 for playback.
[0050] Specifically, the active noise reduction earphone 100 can be an in-ear earphone, a semi-in-ear earphone, or an earphone in a true wireless stereo (TWS) earphone, an earphone in a headphone, etc.
[0051] The feedforward acquisition module 101 may be one or more microphones, also often referred to as extra-ear microphones, which are usually located outside the active noise reduction headphones and are used to collect audio data outside the ears of the wearer.
[0052] The feedforward conversion module 1012 includes an analog gain module, an analog-to-digital converter, and a low-pass and down-sampling filter. The feedforward acquisition module 1011 converts the collected original sound signal into a feedforward sound signal (i.e., an analog electrical signal), and then inputs the feedforward sound signal into the analog gain module for gain processing, and inputs the gain processing result into the analog-to-digital converter for conversion into a digital signal. Afterwards, the low-pass and down-sampling filter performs low-pass and down-sampling processing on the data signal to obtain a first conversion signal, and transmits the first conversion signal to the adaptive control module 102 and the feedforward noise reduction filter 1013.
[0053] In practical applications, the original sound signal collected by the feedforward acquisition module 1011 includes: ambient noise for active noise reduction function and audio signals such as music played by the speaker and leaked into the feedforward acquisition module. The playback module 104 includes: a digital-to-analog converter and a speaker. The digital-to-analog converter performs digital-to-analog conversion on the superimposed signal output by the first superimposition module 103 and sends it to the speaker for playback.
[0054] In an embodiment of the present application, the adaptive control module updates the filter coefficient of the feedforward noise reduction filter through an adaptive algorithm based on the error signal and the first conversion signal output by the feedforward conversion module, so that the filter coefficient of the updated feedforward noise reduction filter is more matched with the current noise scene. Therefore, when the feedforward noise reduction filter filters the first conversion signal based on the updated filter coefficient, the output forward noise signal for noise reduction is also more matched with the current noise scene. Then, after the first superposition module superimposes the forward noise signal with the audio signal to be played, it can adaptively offset the noise signal mixed in the audio signal to be played, thereby achieving a good noise reduction effect, thereby reducing the noise heard by the user's ears and improving the user's experience.
[0055] In some embodiments, see Figure 2 The active noise reduction headset 100 further includes: a feedback noise reduction channel 201; the feedback noise reduction channel 201 includes: a feedback collection module 2011, a feedback conversion module 2022, and a feedback noise reduction filter 2023;
[0056] The feedback collection module 2011 is used to collect the feedback sound signal and transmit the feedback sound signal to the feedback conversion module; the feedback noise reduction filter 2023 is used to filter the second conversion signal output by the feedback conversion module 2022 and output a reverse noise signal.
[0057] The first superposition module 103 is used for superimposing the forward noise signal, the reverse noise signal and the audio signal to be played and transmitting the superimposed signals to the playing module 104 for playing.
[0058] Specifically, the feedback collection module 2011 can be one or more microphones, also often referred to as in-ear microphones, which are usually located on the inside of the active noise reduction headset near the ear canal and are used to collect audio data inside the ear.
[0059] The feedback conversion module 2012 includes an analog gain module, an analog-to-digital converter, and a low-pass and down-sampling filter. The original sound signal collected by the feedback collection module 2011 is processed by the analog gain module, the analog-to-digital converter, and the low-pass and down-sampling filter to output a second conversion signal.
[0060] The feedback noise reduction filter 2023 may be a non-recursive filter, a recursive filter, or a filter structure that is a mixture of a non-recursive filter and a recursive filter.
[0061] In some embodiments, the error signal may be: a feedback sound signal collected by the feedback collection module 2011, or an output signal obtained by low-pass filtering and down-sampling the feedback sound signal.
[0062] The error signal may also be obtained by estimating the audio signal at the position of the virtual microphone, or an output signal obtained by low-pass filtering and down-sampling the audio signal estimated at the position of the virtual microphone, wherein the position of the virtual microphone refers to: the position in the ear canal between the side of the active noise reduction headphone close to the ear canal and the eardrum, especially the position of the ear canal close to the eardrum.
[0063] In some embodiments, see Figure 3 , the active noise reduction headset 100 further includes: an echo module 301; the feedback noise reduction channel 201 further includes: a second superposition module 302;
[0064] The second superposition module 302 is used to superimpose the second conversion signal output by the feedback conversion module 2022 and the audio component of the to-be-played audio signal output by the echo module 301 to obtain an ambient noise signal.
[0065] The feedback noise reduction filter 2023 is used to filter the environmental noise signal and output a reverse noise signal.
[0066] When the active noise reduction headset 100 plays audio, the audio signal to be played is sent to the first superposition module 103 on the one hand, and to the echo module 301 on the other hand. The echo module 301 outputs the audio component of the audio signal to be played, and the second superposition module 302 superimposes the second conversion signal output by the feedback conversion module 2012 and the audio component of the audio signal to be played output by the echo module 301 to offset the audio component of the audio signal to be played in the feedback noise reduction channel 201, so that the sound collected in the feedback noise reduction channel 201 is not affected by the audio to be played.
[0067] The echo module 301 may be an adaptive filter or a fixed filter. In specific implementation, the echo module 301 may be a non-recursive filter, a recursive filter, or a filter structure that is a mixture of a non-recursive filter and a recursive filter.
[0068] Further, after eliminating the influence of the to-be-played audio on the feedback noise reduction channel 201, the remaining environmental noise signal is transmitted to the feedback noise reduction filter 2023 for filtering. In some cases, the reverse noise signal output by the feedback noise reduction filter 2023 can be transmitted to the limiter for processing, and then transmitted to the first superposition module 103 for superposition. Finally, the playing module 104 plays the sound signal obtained by superposition.
[0069] It should be noted that the feedforward noise reduction channel 101 and the feedback noise reduction channel 201 in the embodiment of the present application can be in working state at the same time to achieve noise reduction; or only one of the noise reduction channels can be in working state to achieve noise reduction; this application does not make specific limitations on this.
[0070] In some embodiments, see Figure 4 The adaptive control module 102 includes: a first low-pass filter and down-sampling module 401, an Sz filter 402, and an adaptive module 403. The filter coefficient of the Sz filter 402 corresponds to the transfer function between the playback input signal of the playback module and the feedback sound signal collected by the feedback collection module 2011; the active noise reduction headset 100 also includes: a second low-pass filter and down-sampling module 404.
[0071] The first low-pass filtering and down-sampling module 401 and the Sz filter 402 process the first conversion signal of the first sampling rate in sequence and output an adaptive input signal of a second sampling rate, wherein the second sampling rate is less than the first sampling rate. The second low-pass filtering and down-sampling module 404 is used to process the error signal of the first sampling rate and output an adaptive error signal of the second sampling rate.
[0072] The adaptive module 403 is used to update the filter coefficients of the reference filter operating at the second sampling rate through an adaptive algorithm based on the adaptive input signal and the adaptive error signal; and to update the filter coefficients of the feedforward denoising filter 1013 operating at the first sampling rate through the filter coefficients of the reference filter.
[0073] Specifically, after the first low-pass filtering and down-sampling module 401 processes the first conversion signal of the first sampling rate f1, the sampling rate of the first conversion signal is reduced from the first sampling rate f1 to the second sampling rate f2. The feedforward noise reduction filter 1013 operates at the first sampling rate f1. The adaptive algorithm can be the least mean square (LMS), recursive least mean square (RLS), normalized least mean square (NLMS), etc. In addition, the adaptive algorithm can be implemented in the time domain or the frequency domain.
[0074] In some embodiments, the ratio of the first sampling rate to the second sampling rate is N, that is, N=f1 / f2, where N is a positive integer greater than 1. For example, if the first sampling rate f1 is 768KHz and the second sampling rate f2 is 48KHz, then N is 16.
[0075] For the n coefficients in the filter coefficients of the reference filter, the adaptive module 403 performs the following operations respectively: the i*N+1th coefficient in the filter coefficients of the feedforward denoising filter 1013 is configured as the ith coefficient in the filter coefficients of the reference filter, where i is a positive integer less than or equal to n; at the same time, the other coefficients in the filter coefficients of the feedforward denoising filter 1013 are set to zero. The value of n can be 10, 16, 20, 32, 40, 64, etc.
[0076] The filter coefficients of the reference filter operating at the second sampling rate are updated by an adaptive algorithm; then the N+1th, 2*N+1th, …, i*N+1th coefficients of the filter coefficients of the feedforward denoising filter 1013 are correspondingly configured as the 1st, 2nd, …, i-th coefficients of the filter coefficients of the reference filter (i.e., the filter coefficients of the feedforward denoising filter 1013 are configured based on the filter coefficients of the reference filter with a gain of 1), and the other coefficients of the filter coefficients of the feedforward denoising filter 1013 are configured to zero.
[0077] For example, f1 / f2=8, n=10 is set, the 9th coefficient of the filter coefficients of the feedforward noise reduction filter 1013 is configured as the 1st coefficient of the filter coefficients of the reference filter; the 17th coefficient of the filter coefficients of the feedforward noise reduction filter 1013 is configured as the 2nd coefficient of the filter coefficients of the reference filter; ...; the 81st coefficient of the filter coefficients of the feedforward noise reduction filter 1013 is configured as the 10th coefficient of the filter coefficients of the reference filter. The other coefficients of the filter coefficients of the feedforward noise reduction filter 1013 are configured as 0.
[0078] It should be noted that, in the embodiment of the present application, the filter coefficients of the feedforward denoising filter 1013 can also be configured according to a multiple N as the gain, that is, the filter coefficients of the feedforward denoising filter 1013 mapped from the filter coefficients of the reference filter are multiplied by N; the filter coefficients of the feedforward denoising filter 1013 can also be configured according to other fixed multiples as the gain, and the fixed multiples can be floating-point multiples, and the present application does not make any specific limitation on this.
[0079] In the embodiment of the present application, for the active noise reduction filter, in order to obtain a better noise reduction effect, the delay of the feedforward noise reduction filter is required to be small, and in the filter coefficients of the feedforward noise reduction filter, a non-zero coefficient is set for each fixed multiple of the coefficients, thereby effectively reducing the delay of the feedforward noise reduction filter, so that when converting from a reference filter with a low sampling rate (f2) to a feedforward noise reduction filter with a high sampling rate (f1), the delay will not be increased.
[0080] At the same time, among the filter coefficients of the feedforward noise reduction filter, only 1 / N coefficients of all coefficients are non-zero, and the other zero coefficients do not need to be stored or involved in the calculation, which saves computing resources, reduces the chip area, reduces costs, and reduces power consumption. At the same time, since audio signals above 20KHz cannot be perceived by people, although there are many zero coefficients in the filter coefficients of the feedforward noise reduction filter, which makes the audio signal passing through the feedforward noise reduction filter have high-frequency signals, as long as the audio signal is greater than 20KHz, it will not affect people's hearing.
[0081] In some embodiments, see Figure 5 When the active noise reduction headset includes the feedback noise reduction channel 201, the adaptive control module 102 also includes: a feedback closed-loop filter 501, and the filter coefficient of the feedback closed-loop filter 501 is determined based on the filter coefficient of the feedback noise reduction filter 2023 and the filter coefficient of the Sz filter 402, as shown in the following formula (1):
[0082] H1=1 / (1+FB_W*Sz)…………(1)
[0083] Wherein, H1 represents the transfer function of the feedback closed-loop filter 501, and the transfer function of the feedback closed-loop filter 501 corresponds to the filter coefficient of the feedback closed-loop filter 501;
[0084] FB_W represents the transfer function of the feedback noise reduction filter 2023, and the transfer function of the feedback noise reduction filter 2023 corresponds to the filter coefficient of the feedback noise reduction filter 2023;
[0085] Sz represents the transfer function of the Sz filter 402 , and the transfer function of the Sz filter 402 corresponds to the filter coefficient of the Sz filter 402 .
[0086] The first low-pass filtering and down-sampling module 401, the Sz filter 402 and the feedback closed-loop filter 501 sequentially process the first conversion signal of the first sampling rate and output an adaptive input signal of the second sampling rate.
[0087] In the embodiment of the present application, in the adaptive control module 102, the first conversion signal is also input into the adaptive module 403 after passing through the feedback closed-loop filter 501, and is used to update the filter coefficient of the feedforward noise reduction filter 1013, so that the residual noise can be smaller and the adaptive convergence time can be shorter; for various noise scenarios, the stability of the adaptive noise reduction is also better, that is, the overall noise reduction effect is better in various noise scenarios.
[0088] In some embodiments, see Figure 6 , the adaptive control module 102 further includes: a first low-pass filter 601; the active noise reduction headset 100 further includes: a second low-pass filter 602;
[0089] The first low-pass filtering and down-sampling module 401, the Sz filter 402, the first low-pass filter 601 and the feedback closed-loop filter 501 sequentially process the first conversion signal of the first sampling rate and output an adaptive input signal of the second sampling rate.
[0090] The second low-pass filtering and down-sampling module 404 and the second low-pass filter 602 process the error signal of the first sampling rate in sequence and output an adaptive error signal of the second sampling rate.
[0091] Specifically, the bandwidth of the first low-pass filter 601 and the second low-pass filter 602 can be 2KHz, 3KHz, 4KHz, 5KHz, etc. In some embodiments, the first low-pass filter 601 and the second low-pass filter 602 are the same filter. After the first conversion signal and the error signal are processed by a low-pass filter respectively, the adaptive noise reduction is easier to converge and the stability of the noise reduction is better.
[0092] In some embodiments, the state (position, orientation, tightness, etc.) of the earphone relative to the ear may change while the user is wearing the earphone. For example, the user adjusts the earphone (adjusts the wearing orientation, tightness, etc.), and the earphone changes state (wears more loosely, the earphone position changes, etc.) during wearing. This is more likely to happen when the user is exercising.
[0093] In order to improve the stability of the adaptive control module in adapting the feedforward noise reduction filter, the embodiment of the present application at least uses the following implementation to trigger the adaptive control module to start adaptive iteration:
[0094] When the state of the earphone relative to the ear (position, orientation, tightness, etc.) changes, the transfer function of the Sz filter will often change. Therefore, the active noise reduction earphone can detect the transfer function of the Sz filter regularly or in real time. After the adaptive control module 102 updates the filter coefficient of the feedforward noise reduction filter 1013, if the change value of the transfer function of the Sz filter is greater than the preset threshold, the adaptive control module 102 re-adaptively updates the filter coefficient of the feedforward noise reduction filter 1013. The transfer function of the Sz filter refers to: the transfer function between the playback input signal of the playback module and the feedback sound signal or some parameters of the transfer function.
[0095] Specifically, when calculating the change value of the transfer function of the Sz filter, a certain frequency band can be used, and a frequency band obtained by weighted average of multiple independent frequency bands can also be used. For example, one or more frequency bands are first selected in the low frequency band, and the low frequency can be a frequency band below 1.5KHz (such as 200Hz, 500Hz, 800Hz, 1K Hz, etc.). Based on the amplitude or phase change of the transfer function of the Sz filter in the selected frequency band, as the change value of the transfer function of the Sz filter, correspondingly, a corresponding preset threshold is set on the amplitude or phase change in the selected frequency band, for example, the preset threshold on the amplitude can be 3db, 5db, 6db, etc.
[0096] In an optional implementation, the feedforward noise reduction filter 1013 includes: a non-recursive filter and a group of recursive filters, the non-recursive filter and the group of recursive filters are connected in series or in parallel, the non-recursive filter is an adaptive filter, and the recursive filter is a filter with fixed coefficients.
[0097] Specifically, the adaptive control module 102 performs adaptive iterative control on the non-recursive filter therein, and in a laboratory scenario, based on an artificial ear or a human ear, adjusts the recursive filter under normal wearing conditions to achieve the best or near-best noise reduction effect or a noise reduction amount reaching a threshold value 1.
[0098] In some cases, N (N>1) groups of fixed coefficients of different recursive filters can be configured based on different wearing tightness. When the user wears the headphones, a group of fixed coefficients of the recursive filter is selected from the preset multiple groups of filter coefficients based on the transfer function of the Sz filter to configure the filter coefficients of the recursive filter in the feedforward noise reduction filter 1013.
[0099] The transfer function of the Sz filter based on the active noise reduction headphones selects fixed coefficients that match the recursive filter of the feedforward noise reduction filter 1013, which can not only improve the adaptive convergence speed of the non-recursive filter and increase the noise reduction amount, but also reduce the order of the non-recursive filter, thereby effectively improving the noise reduction effect and reducing costs and power consumption, such as reducing chip area.
[0100] It should be noted that, in addition to the feedforward noise reduction filter 1013 described in the above embodiment, the feedforward noise reduction filter 1013 may also include: a recursive filter and a group of non-recursive filters, the recursive filter and the group of non-recursive filters are connected in series or in parallel, the recursive filter is an adaptive filter, and the non-recursive filter is a filter with fixed coefficients. In addition, the feedforward noise reduction filter 1013 may also include only an adaptive non-recursive filter, or only an adaptive recursive filter, and this application does not make specific limitations on this.
[0101] Based on the same technical concept, the embodiment of the present application provides an electronic device, which can be a computer device Figure 1 Active noise canceling headphones, such as Figure 7 As shown, it includes at least one processor 701 and a memory 702 connected to the at least one processor. The specific connection medium between the processor 701 and the memory 702 is not limited in the embodiment of the present application. Figure 7 For example, the processor 701 and the memory 702 are connected via a bus. The bus can be divided into an address bus, a data bus, a control bus, etc.
[0102] In the embodiment of the present application, the memory 702 stores instructions that can be executed by at least one processor 701, and the at least one processor 701 can perform the above-mentioned process of adaptively adjusting the filter coefficients by executing the instructions stored in the memory 702.
[0103] Among them, the processor 701 is the control center of the computer device, and various interfaces and lines can be used to connect various parts of the computer device, and actively reduce noise by running or executing instructions stored in the memory 702 and calling data stored in the memory 702. Optionally, the processor 701 may include one or more processing units, and the processor 701 may integrate an application processor and a modem processor, wherein the application processor mainly processes the operating system, user interface, and application programs, and the modem processor mainly processes wireless communications. It is understandable that the above-mentioned modem processor may not be integrated into the processor 701. In some embodiments, the processor 701 and the memory 702 may be implemented on the same chip, and in some embodiments, they may also be implemented separately on separate chips.
[0104] Processor 701 can be a general-purpose processor, such as a central processing unit (CPU), a digital signal processor, an application-specific integrated circuit (ASIC), a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, and can implement or execute the various methods, steps and logic block diagrams disclosed in the embodiments of the present application. A general-purpose processor can be a microprocessor or any conventional processor, etc. The steps of the method disclosed in the embodiments of the present application can be directly embodied as a hardware processor for execution, or can be executed by a combination of hardware and software modules in the processor.
[0105] The memory 702 is a non-volatile computer-readable storage medium that can be used to store non-volatile software programs, non-volatile computer executable programs and modules. The memory 702 may include at least one type of storage medium, such as a flash memory, a hard disk, a multimedia card, a card-type memory, a random access memory (Random Access Memory, RAM), a static random access memory (Static Random Access Memory, SRAM), a programmable read-only memory (Programmable Read Only Memory, PROM), a read-only memory (Read Only Memory, ROM), an electrically erasable programmable read-only memory (Electrically Erasable Programmable Read-Only Memory, EEPROM), a magnetic memory, a disk, an optical disk, etc. The memory 702 is any other medium that can be used to carry or store a desired program code in the form of an instruction or data structure and can be accessed by a computer device, but is not limited thereto. The memory 702 in the embodiment of the present application can also be a circuit or any other device that can realize a storage function, for storing program instructions and / or data.
[0106] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.
[0107] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer device or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.
[0108] These computer program instructions may also be stored in a computer readable memory capable of directing a computer device or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.
[0109] These computer program instructions can also be loaded onto a computer device or other programmable data processing device so that a series of operation steps are executed on the computer device or other programmable device to produce a process implemented by the computer device, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.
[0110] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.
[0111] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.
Claims
1. An active noise reduction headset, It is characterized in that include: A feedforward noise reduction channel, an adaptive control module, a first superposition module and a playback module, wherein the feedforward noise reduction channel includes: a feedforward acquisition module, a feedforward conversion module and a feedforward noise reduction filter; The feedforward acquisition module is used to collect the feedforward sound signal and transmit the feedforward sound signal to the feedforward conversion module; The adaptive control module is used to update the filter coefficient of the feedforward noise reduction filter through an adaptive algorithm based on the error signal and the first conversion signal output by the feedforward conversion module; The feedforward noise reduction filter is used to filter the first conversion signal based on the updated filter coefficient and output a forward noise signal; The first superposition module is used to superimpose the forward noise signal and the audio signal to be played and transmit the superposition signals to the playing module for playing.
2. The active noise reduction headset according to claim 1, It is characterized in that The active noise reduction headset further includes: a feedback noise reduction channel; the feedback noise reduction channel includes: a feedback collection module, a feedback conversion module, and a feedback noise reduction filter; The feedback collection module is used to collect feedback sound signals and transmit the feedback sound signals to the feedback conversion module; The feedback noise reduction filter is used to filter the second conversion signal output by the feedback conversion module and output the reverse noise signal; The first superposition module is used to superimpose the forward noise signal, the reverse noise signal, and the audio signal to be played, and then transmit them to the playing module for playing.
3. The active noise reduction headset according to claim 2, It is characterized in that The active noise reduction headset further includes: an echo module; the feedback noise reduction channel further includes: a second superposition module; The second superposition module is used to superimpose the second conversion signal output by the feedback conversion module and the audio component of the to-be-played audio signal output by the echo module to obtain an ambient noise signal; The feedback noise reduction filter is used to filter the environmental noise signal and output the reverse noise signal.
4. The active noise reduction headset according to claim 2, It is characterized in that The adaptive control module includes: a first low-pass filter and down-sampling module, an Sz filter, and an adaptive module; the filter coefficient of the Sz filter corresponds to: a transfer function between the playback input signal of the playback module and the feedback sound signal collected by the feedback collection module; the active noise reduction headset also includes: a second low-pass filter and down-sampling module; The first low-pass filtering and down-sampling module and the Sz filter sequentially process the first conversion signal of the first sampling rate and output an adaptive input signal of a second sampling rate, wherein the second sampling rate is less than the first sampling rate; The second low-pass filtering and down-sampling module is used to process the error signal of the first sampling rate and output an adaptive error signal of the second sampling rate; The adaptive module is used to update the filter coefficients of the reference filter operating at the second sampling rate through an adaptive algorithm based on the adaptive input signal and the adaptive error signal; and to update the filter coefficients of the feedforward denoising filter operating at the first sampling rate through the filter coefficients of the reference filter.
5. The active noise reduction headset according to claim 4, It is characterized in that The ratio of the first sampling rate to the second sampling rate is N, where N is a positive integer greater than 1; For n coefficients in the filter coefficients of the reference filter, the adaptive module performs the following operations respectively: configuring the i*N+1th coefficient in the filter coefficients of the feedforward denoising filter as the ith coefficient in the filter coefficients of the reference filter, where i is a positive integer less than or equal to n; The adaptive module is further used to set other coefficients in the filter coefficients of the feedforward denoising filter to zero.
6. The active noise reduction headset according to claim 4, It is characterized in that The adaptive control module further includes: a feedback closed-loop filter, wherein the filter coefficient of the feedback closed-loop filter is determined based on the filter coefficient of the feedback noise reduction filter and the filter coefficient of the Sz filter; The first low-pass filtering and down-sampling module, the Sz filter and the feedback closed-loop filter sequentially process the first conversion signal of the first sampling rate and output an adaptive input signal of the second sampling rate.
7. The active noise reduction headset according to claim 6, It is characterized in that The adaptive control module further includes: a first low-pass filter; the active noise reduction headset further includes: a second low-pass filter; The first low-pass filtering and down-sampling module, the Sz filter, the first low-pass filter and the feedback closed-loop filter sequentially process the first conversion signal of the first sampling rate and output an adaptive input signal of the second sampling rate; The second low-pass filtering and down-sampling module and the second low-pass filter process the error signal of the first sampling rate in sequence and output an adaptive error signal of the second sampling rate.
8. The active noise reduction headset according to any one of claims 2 to 7, It is characterized in that The feedforward noise reduction filter comprises: A non-recursive filter and a group of recursive filters, wherein the non-recursive filter and the group of recursive filters are connected in series or in parallel, the non-recursive filter is an adaptive filter, and the recursive filter is a filter with fixed coefficients.
9. The active noise reduction headset according to claim 8, It is characterized in that The fixed coefficients corresponding to the set of recursive filters are selected from multiple preset sets of filter coefficients based on the transfer function of the Sz filter, and the transfer function of the Sz filter refers to: the transfer function between the playback input signal of the playback module and the feedback sound signal.
10. The active noise reduction headset according to claim 9, It is characterized in that Also includes: After the adaptive control module updates the filter coefficients of the feedforward noise reduction filter, if the change value of the transfer function of the Sz filter is greater than a preset threshold, the adaptive control module adaptively updates the filter coefficients of the feedforward noise reduction filter again.