Active noise reduction method and active noise reduction audio device

Abstract

The present invention relates to the field of audio noise reduction, and specifically to an active noise reduction method and an active noise reduction audio device, comprising: using multiple feedforward microphones to collect and obtain feedforward sound signal spectra from different directions, and using a feedback microphone to collect and obtain the feedback sound signal spectrum inside the active noise reduction audio device; dynamically updating the parameters of the filter of the feedforward channel at the current moment according to the parameters of the filter of the feedforward channel between each feedforward microphone and the feedback microphone at the previous moment, and filtering the feedforward sound signal spectrum in the feedforward channel through the filter; calculating the weight value corresponding to each feedforward microphone at the current moment according to the correlation between each feedforward microphone and the feedback microphone at the current moment; and mixing the filtered feedforward sound signal spectra according to the weight value corresponding to each feedforward microphone to obtain a noise-reduced sound signal. The present invention can significantly improve the stability and accuracy of the noise reduction effect and enhance the noise reduction experience.

Description

Technical Field

[0001] The present invention relates to the field of audio noise reduction, and in particular to an active noise reduction method and an active noise reduction audio device. Background Art

[0002] Noise cancellation technology, particularly active noise cancellation (ANC), plays a vital role in our daily lives and work. It's widely used in a variety of devices, including headphones, hearing aids, and industrial equipment, to reduce ambient noise and improve audio quality, allowing people to better hear audio content in noisy environments. Noise cancellation technology not only provides a more comfortable listening environment and reduces the potential damage to hearing caused by noise, but also has a positive impact on work efficiency and mental health.

[0003] Currently, the industry generally uses an adaptive ANC algorithm based on a feedforward microphone to achieve noise reduction. In this solution, after the noise reduction of the headphones is turned on, the feedforward microphone and the feedback microphone will collect the sound signal, and then run the adaptive ANC algorithm based on these signals. This algorithm calculates a set of filter parameters and sets these parameters to the hardware filter. In this way, the noise reduction effect is achieved in the current wearing state, thereby providing a better noise reduction experience. However, this method may have poor noise reduction effects when facing rapidly changing ambient noise or complex noise characteristics. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides an active noise reduction method and an active noise reduction audio device.

[0005] A first aspect of the present invention discloses an active noise reduction method, which is applied to an active noise reduction audio device, wherein the active noise reduction audio device includes multiple feedforward microphones, a feedback microphone, and an audio output port. The method includes:

[0006] Using the plurality of feedforward microphones to collect and obtain feedforward sound signal spectra from different directions, and using the feedback microphone to collect and obtain feedback sound signal spectra inside the active noise reduction audio device;

[0007] Dynamically updating the filter parameters of the feedforward channel between each of the feedforward microphones and the feedback microphone at the previous moment according to the filter parameters of the feedforward channel at the current moment, and filtering the feedforward sound signal spectrum in the feedforward channel through the filter;

[0008] Calculating a weight value corresponding to each of the feedforward microphones at the current moment according to a correlation between each of the feedforward microphones and the feedback microphone at the current moment;

[0009] According to the weight value corresponding to each of the feedforward microphones, the frequency spectra of the filtered feedforward sound signals are mixed to obtain a noise-reduced sound signal.

[0010] Furthermore, the steps of using the plurality of feedforward microphones to collect and obtain feedforward sound signal spectra from different directions, and using the feedback microphone to collect and obtain feedback sound signal spectra inside the active noise reduction audio device include:

[0011] Collecting multiple feedforward time-domain sound signals at the current moment through the multiple feedforward microphones;

[0012] Collecting the feedback time-domain sound signal at the current moment through the feedback microphone;

[0013] Perform frequency domain conversion on the feedback time domain sound signal and the plurality of feedforward time domain sound signals to obtain and save corresponding frequency spectra of the feedback sound signal and the plurality of feedforward sound signal frequency spectra.

[0014] Furthermore, the step of dynamically updating the filter parameters of the feedforward channel between each of the feedforward microphones and the feedback microphone at the previous moment includes:

[0015] The parameters of the filter are adaptively updated according to a feedback frequency response function, the feedback sound signal spectrum at a previous moment, and the feedforward sound signal spectrum at a previous moment; wherein the feedback frequency response function represents a frequency response function between the feedback microphone and the audio output port.

[0016] Furthermore, the feedback frequency response function is obtained in advance according to the following calculation steps:

[0017] Calculating a feedforward frequency response function corresponding to each feedforward microphone, where the feedforward frequency response function represents a frequency response function between the feedforward microphone and the feedback microphone;

[0018] Based on all the feedforward frequency response functions, the feedback frequency response function S is calculated:

[0019] S=

[0020] [fb req (T1)-mean(ff1 req (T1)×P1,ff2 req (T1)×P2,…,ffN req (T1)×P N)] / ref req ;

[0021] Among them, fb req (T1) represents the feedback sound signal spectrum corresponding to the T1 frame, mean() represents the mean operation, N represents the number of the feedforward microphones, ref req represents the reference signal, ffN req (T1) represents the feedforward sound signal spectrum corresponding to the Nth feedforward microphone at the T1th frame, P N represents the feedforward frequency response function corresponding to the Nth feedforward microphone.

[0022] Furthermore, the step of calculating the feedforward frequency response function corresponding to each feedforward microphone includes:

[0023] For each of the feedforward microphones:

[0024] When the active noise reduction function is turned off, a ratio of the feedback sound signal spectrum of the feedback microphone to the feedforward sound signal spectrum of the feedforward microphone is calculated as the feedforward frequency response function of the feedforward microphone.

[0025] Furthermore, the reference signal is an output signal of the audio output port.

[0026] Furthermore, the step of calculating the weight value corresponding to each of the feedforward microphones at the current moment according to the correlation between each of the feedforward microphones and the feedback microphone at the current moment includes:

[0027] Calculating the correlation between each of the feedforward microphones and the feedback microphone at the current moment as the signal propagation correlation of each feedforward microphone at the current moment;

[0028] Summing the signal propagation correlations of all feedforward microphones at the current moment to obtain the system signal propagation correlation at the current moment;

[0029] The weight value of each feedforward microphone is obtained according to the signal propagation correlation of each feedforward microphone and the system signal propagation correlation at the current moment.

[0030] Furthermore, the step of obtaining a weight value of each feedforward microphone according to the signal propagation correlation of each feedforward microphone and the system signal propagation correlation at the current moment includes:

[0031] For each feedforward microphone:

[0032] The ratio of the signal propagation correlation of the feedforward microphone to the system signal propagation correlation at the current moment is calculated as the weight value of the feedforward microphone.

[0033] Furthermore, the step of mixing the filtered feedforward sound signal spectra according to the weight value corresponding to each feedforward microphone to obtain the noise-reduced sound signal includes:

[0034] The filtered feedforward sound signal spectra of each feedforward channel are mixed according to the weight value corresponding to each feedforward microphone to obtain a mixed output frequency domain signal:

[0035] output(T3)=scale1(T3)×ff1 req (T3)*ω1(T3)+…+scaleN(T3)×ffN req (T3)*ωN(T3);

[0036] Among them, output(T3) represents the output frequency domain signal corresponding to the T3th frame, scaleN(T3) represents the weight value corresponding to the Nth feedforward microphone at the T3th frame, ffN req (T3) represents the feedforward sound signal spectrum corresponding to the Nth feedforward microphone at the T3th frame, ωN(T3) represents the parameters of the filter corresponding to the Nth feedforward microphone at the T3th frame, and * represents convolution calculation;

[0037] Perform inverse Fourier transform on the output frequency domain signal to obtain a noise-reduced sound signal.

[0038] A second aspect of the present invention discloses an active noise reduction audio device, which includes multiple feedforward microphones, a feedback microphone and an audio output port, and can perform any active noise reduction method disclosed in the first aspect of the present invention.

[0039] The present invention calculates the correlations between the signals from multiple feedforward microphones and uses these correlation values ​​as weights to mix the feedforward signals, thereby generating a comprehensive and accurate noise signal. Furthermore, the present invention employs an adaptive filter algorithm that can adjust the filter parameters in real time to adapt to changes in the noise environment. As a result, the present invention significantly improves the stability and accuracy of the noise reduction effect, enhancing the noise reduction experience, especially in complex and changing noise environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 creative work.

[0041] Figure 1 This is a flow chart of an active noise reduction method disclosed in an embodiment of the present invention;

[0042] Figure 2 This is a schematic diagram of the principle of an active noise reduction method disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0044] The terms "first," "second," and so on, in the description and claims of the present invention and the accompanying drawings are used to distinguish between different items, not to describe a specific order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, apparatus, or product comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to such process, method, product, or end.

[0045] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute a separate or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0046] Example 1

[0047] See also Figure 1 As shown, Figure 1 This is a flow chart of an active noise reduction method disclosed in an embodiment of the present invention. The active noise reduction method is applied to an active noise reduction audio device, and the active noise reduction audio device includes multiple feedforward microphones, a feedback microphone, and an audio output port. The active noise reduction audio device can be various devices that require active noise reduction functions, such as headphones, speakers, home theaters, etc., and the present invention does not limit this. The present invention can be applied in smart homes, industrial production, health care, environmental monitoring and other fields, and the present invention does not limit this. Figure 1 As shown, the active noise reduction method may include the following operations:

[0048] S100: using the plurality of feedforward microphones to collect and obtain feedforward sound signal spectra from different directions, and using the feedback microphone to collect and obtain feedback sound signal spectra inside the active noise reduction audio device;

[0049] A single feedforward microphone is limited to its single position and angle, and can often only effectively capture and suppress noise from a specific direction. However, in actual applications, noise sources may come from multiple different directions, and the nature and intensity of these noise sources may also change over time. This embodiment, by utilizing the data of multiple feedforward microphones in different positions, can capture noise signals in the environment from all directions and angles. When faced with scenes with noise sources from different directions, the introduction of multiple feedforward microphones in different positions can achieve a more excellent noise reduction effect, ensuring that users can enjoy a clearer and quieter listening experience in different environments.

[0050] In one optional embodiment, feedforward microphones are placed at different locations or directions within the active noise cancellation audio device to capture ambient sound from different directions. The number, location, and direction of the microphones can be determined based on the device's shape and usage environment. Feedback microphones are placed inside the active noise cancellation audio device, near the audio output port, to monitor the device's output.

[0051] For example, multiple feedforward microphones can be used to collect feedforward sound signal spectra from different directions based on directional microphone array technology, which can improve the active noise reduction system's ability to perceive sounds in complex environments, positioning accuracy, and noise reduction effect, thereby providing users with a better audio experience.

[0052] S200, dynamically updating the parameters of the filter of the feedforward channel between each of the feedforward microphones and the feedback microphone at the previous moment, and filtering the feedforward sound signal spectrum in the feedforward channel through the filter;

[0053] In this embodiment, the filter may be an FIR filter or an IIR filter. Due to the advantages of the FIR filter, such as good stability, ease of design, and ability to achieve linear phase characteristics, the FIR filter is preferred.

[0054] S300, calculating a weight value corresponding to each of the feedforward microphones at the current moment according to a correlation between each of the feedforward microphones and the feedback microphone at the current moment;

[0055] S400 : According to the weight value corresponding to each of the feedforward microphones, the frequency spectra of the filtered feedforward sound signals are mixed to obtain a noise-reduced sound signal.

[0056] The present invention calculates the correlations between the signals from multiple feedforward microphones and uses these correlation values ​​as weights to mix the feedforward signals, thereby generating a comprehensive and accurate noise signal. Furthermore, the present invention employs an adaptive filter algorithm that can adjust the filter parameters in real time to adapt to changes in the noise environment. As a result, the present invention significantly improves the stability and accuracy of the noise reduction effect, enhancing the noise reduction experience, especially in complex and changing noise environments.

[0057] In an optional embodiment, the specific steps of using multiple feedforward microphones to collect and obtain feedforward sound signal spectra from different directions, and using the feedback microphone to collect and obtain the feedback sound signal spectrum inside the active noise reduction audio device may include:

[0058] Collecting multiple feedforward time-domain sound signals at the current moment through the multiple feedforward microphones;

[0059] Collecting the feedback time-domain sound signal at the current moment through the feedback microphone;

[0060] Perform frequency domain conversion on the feedback time domain sound signal and the plurality of feedforward time domain sound signals to obtain and save corresponding frequency spectra of the feedback sound signal and the plurality of feedforward sound signal frequency spectra.

[0061] This can be achieved by installing a dedicated sound acquisition module on each feedforward microphone, for example, using a high-precision analog-to-digital converter to acquire sound signals, and using a digital signal processor to perform preliminary processing on the acquired sound signals.

[0062] After frequency domain conversion, the feedback sound signal spectrum and the multiple feedforward sound signal spectrums can be optimized using filtering, equalization, compression and other technologies.

[0063] In this optional embodiment, frequency domain conversion refers to performing Fourier transform on the time domain sound signal to obtain a frequency domain signal.

[0064] In an optional embodiment, the step of dynamically updating the filter parameters of the feedforward channel between each of the feedforward microphones and the feedback microphone at the previous moment includes:

[0065] The parameters of the filter are adaptively updated according to a feedback frequency response function, the feedback sound signal spectrum at a previous moment, and the feedforward sound signal spectrum at a previous moment; wherein the feedback frequency response function represents a frequency response function between the feedback microphone and the audio output port.

[0066] In this optional embodiment, taking the filter parameters of the feedforward channel corresponding to the first feedforward microphone as an example, the filter parameters w1(T+1) at frame T+1 are:

[0067] w1(T+1)=w1(T)+μ×ff1 req (T+1)×S×fb req (T+1);

[0068] Among them, μ represents the update step size, ff1 req (T+1) represents the feedforward sound signal spectrum of the first feedforward microphone at the T+1 frame, S represents the feedback frequency response function, fb req (T+1) represents the feedback sound signal spectrum at the T+1th frame.

[0069] In this optional embodiment, further optionally, the feedback frequency response function is obtained in advance according to the following calculation steps:

[0070] Calculating a feedforward frequency response function corresponding to each feedforward microphone, where the feedforward frequency response function represents a frequency response function between the feedforward microphone and the feedback microphone;

[0071] Based on all the feedforward frequency response functions, the feedback frequency response function S is calculated:

[0072] S=

[0073] [fb req (T1)-mean(ff1 req (T1)×P1,ff2 req (T1)×P2,…,ffN req (T1)×P N )] / refr req ;

[0074] Among them, fb req (T1) represents the feedback sound signal spectrum corresponding to the T1 frame, mean() represents the mean operation, N represents the number of the feedforward microphones, ref req represents the reference signal, ffN req (T1) represents the feedforward sound signal spectrum corresponding to the Nth feedforward microphone at the T1th frame, P N represents the feedforward frequency response function corresponding to the Nth feedforward microphone.

[0075] Furthermore, the reference signal can optionally be a pre-recorded noise sample or a real-time noise signal. In this embodiment, the reference signal is the output signal of the audio output port. Using the output signal of the audio output port as the reference signal enables real-time monitoring and adjustment of the output sound quality, thereby improving the sound quality of the audio device.

[0076] Further optionally, the step of calculating the feedforward frequency response function corresponding to each feedforward microphone includes:

[0077] For each of the feedforward microphones:

[0078] When the active noise reduction function is disabled, the ratio of the feedback sound signal spectrum of the feedback microphone to the feedforward sound signal spectrum of the feedforward microphone is calculated as the feedforward frequency response function of the feedforward microphone. This ratio can be understood as the propagation loss of the noise signal between the feedforward microphone and the feedback microphone and can be used to estimate the feedforward frequency response function of each feedforward microphone.

[0079] In this optional embodiment, the feedforward frequency response function P1 corresponding to the first feedforward microphone is taken as an example:

[0080] P1=fb req (T2) / ff1 req (T2);

[0081] Among them, fb req (T2) represents the feedback sound signal spectrum corresponding to the T2 frame, ff1 req (T2) represents the feedforward sound signal spectrum corresponding to the first feedforward microphone at the T2th frame.

[0082] By calculating the ratio of the feedback sound signal spectrum to the feedforward sound signal spectrum when the active noise reduction function is turned off, the feedforward frequency response function of each feedforward microphone can be obtained more accurately, thereby improving the active noise reduction effect.

[0083] In an optional embodiment, the step of calculating the weight value corresponding to each of the feedforward microphones at the current moment according to the correlation between each of the feedforward microphones and the feedback microphone at the current moment may include:

[0084] Calculating the correlation between each of the feedforward microphones and the feedback microphone at the current moment as the signal propagation correlation of each feedforward microphone at the current moment;

[0085] Summing the signal propagation correlations of all feedforward microphones at the current moment to obtain the system signal propagation correlation at the current moment;

[0086] The weight value of each feedforward microphone is obtained according to the signal propagation correlation of each feedforward microphone and the system signal propagation correlation at the current moment.

[0087] By calculating the correlation between the feedforward microphone and the feedback microphone to determine the weight value of each feedforward microphone, sound signals from all directions can be captured more accurately, thereby improving the active noise reduction effect.

[0088] In a further optional embodiment, the step of obtaining a weight value of each feedforward microphone according to the signal propagation correlation of each feedforward microphone and the system signal propagation correlation at the current moment includes:

[0089] For each feedforward microphone:

[0090] The ratio of the signal propagation correlation of the feedforward microphone to the system signal propagation correlation at the current moment is calculated as the weight value of the feedforward microphone.

[0091] In this optional embodiment, the weight value scale1 corresponding to the first feedforward microphone at the current moment is:

[0092] scale1=cor1 / (cor1+cor2+,,,+corN);

[0093] where corN represents the signal propagation correlation of the Nth feedforward microphone.

[0094] In this optional embodiment, calculating the correlation between the feedforward microphone and the feedback microphone may involve calculating a cross-correlation function between the feedforward time-domain sound signal and the feedback time-domain sound signal of the feedforward microphone to obtain the correlation. Alternatively, the correlation between the feedforward time-domain sound signal and the feedback time-domain sound signal may be calculated using a covariance function, information theory methods, or the like.

[0095] By calculating the ratio of the signal propagation correlation to the system signal propagation correlation to obtain the weight value of the feedforward microphone, the importance of each feedforward microphone in the active noise reduction system of the active noise reduction audio device can be more accurately reflected, thereby improving the active noise reduction effect.

[0096] In an optional embodiment, the step of mixing the filtered feedforward sound signal spectra according to the weight value corresponding to each feedforward microphone to obtain the noise-reduced sound signal may include:

[0097] The filtered feedforward sound signal spectra of each feedforward channel are mixed according to the weight value corresponding to each feedforward microphone to obtain a mixed output frequency domain signal:

[0098] output(T3)=scale1(T3)×ff1 req (T3)*ω1(T3)+…+scaleN(T3)×

[0099] ffN req (T3)*ωN(T3);

[0100] Among them, output(T3) represents the output frequency domain signal corresponding to the T3th frame, scaleN(T3) represents the weight value corresponding to the Nth feedforward microphone at the T3th frame, ffN req (T3) represents the feedforward sound signal spectrum corresponding to the Nth feedforward microphone at the T3th frame, ωN(T3) represents the parameters of the filter corresponding to the Nth feedforward microphone at the T3th frame, and * represents convolution calculation;

[0101] Perform inverse Fourier transform on the output frequency domain signal to obtain a noise-reduced sound signal.

[0102] Traditional single-feedforward ANC algorithms can face challenges when dealing with multiple noise sources, as noise signals from different directions can interfere with each other within a single channel, affecting the noise reduction effect. However, the present invention utilizes a multi-feedforward path data fusion algorithm to effectively integrate the noise signals captured by each feedforward microphone and accurately calculate the required reverse noise signals for each channel. These optimized reverse noise signals not only accurately cancel out their respective noise sources but also coordinate with each other in time and space, producing a positive superposition effect, further enhancing overall noise reduction performance.

[0103] Figure 2 This figure shows the principle diagram of the active noise reduction method of this embodiment. The figure shows the Filtered-x Least Mean Squares (FxLMS) algorithm. FxLMS adjusts the filter weights by comparing it with a reference signal to minimize the mean square error of the error signal, effectively helping the system remove noise and improve signal quality. NLMS, which stands for Normalized Least Mean Squares (NLMS), adjusts the filter weights based on the error signal between the input signal and the estimated output. This algorithm is highly adaptive and can quickly adapt to signal changes, improving the noise reduction effect.

[0104] FF1 represents the feedforward sound signal spectrum corresponding to the first feedforward microphone, FF2 represents the feedforward sound signal spectrum corresponding to the second feedforward microphone, FFN represents the feedforward sound signal spectrum corresponding to the Nth feedforward microphone, P1 represents the feedforward frequency response function corresponding to the first feedforward microphone, P2 represents the feedforward frequency response function corresponding to the second feedforward microphone, W1 represents the parameters of the filter of the feedforward channel corresponding to the first feedforward microphone, W2 represents the parameters of the filter of the feedforward channel corresponding to the second feedforward microphone, FB represents the feedback sound signal spectrum, and S represents the feedback frequency response function.

[0105] Example 2

[0106] The present invention provides an active noise reduction audio device, comprising multiple feedforward microphones, a feedback microphone, and an audio output port, and capable of performing the active noise reduction method described in any one of the first embodiments. The present invention does not limit the active noise reduction function to any device requiring active noise reduction, such as headphones, speakers, and home theater systems.

[0107] In summary, the active noise reduction method and device disclosed in this invention significantly improve the stability and accuracy of noise reduction, enhancing the noise reduction experience. This is particularly advantageous in complex and changing noise environments. Therefore, this invention effectively overcomes the shortcomings of existing technologies and possesses high industrial value.

[0108] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. An active noise reduction method, characterized in that: The active noise reduction method is applied to an active noise reduction audio device, wherein the active noise reduction audio device includes multiple feedforward microphones, a feedback microphone, and an audio output port. The method includes: Using the plurality of feedforward microphones to collect and obtain feedforward sound signal spectra from different directions, and using the feedback microphone to collect and obtain feedback sound signal spectra inside the active noise reduction audio device; Dynamically updating the filter parameters of the feedforward channel between each of the feedforward microphones and the feedback microphone at the previous moment according to the filter parameters of the feedforward channel at the current moment, and filtering the feedforward sound signal spectrum in the feedforward channel through the filter; Calculating a weight value corresponding to each of the feedforward microphones at the current moment according to a correlation between each of the feedforward microphones and the feedback microphone at the current moment; Mixing the filtered feedforward sound signal spectra according to the weight value corresponding to each feedforward microphone to obtain a noise-reduced sound signal; The step of dynamically updating the filter parameters of the feedforward channel between each of the feedforward microphones and the feedback microphone at a previous moment according to the filter parameters of the feedforward channel at a previous moment includes: Adaptively updating the filter parameters according to a feedback frequency response function, the feedback sound signal spectrum at a previous moment, and the feedforward sound signal spectrum at a previous moment; wherein the feedback frequency response function represents a frequency response function between the feedback microphone and the audio output port; The feedback frequency response function is obtained in advance according to the following calculation steps: Calculating a feedforward frequency response function corresponding to each feedforward microphone, where the feedforward frequency response function represents a frequency response function between the feedforward microphone and the feedback microphone; Based on all the feedforward frequency response functions, the feedback frequency response function S is calculated: S=[fb req (T1)-mean(ff1 req (T1)×P1,ff2 reeq (T1)×P2,…,ffN req (T1)×P N )] / ref req ; Among them, fb req (T1) represents the feedback sound signal spectrum corresponding to the T1 frame, mean() represents the mean operation, N represents the number of the feedforward microphones, ref req represents the reference signal, ffN req (T1) represents the feedforward sound signal spectrum corresponding to the Nth feedforward microphone at the T1th frame, P N represents the feedforward frequency response function corresponding to the Nth feedforward microphone.

2. The active noise reduction method according to claim 1, wherein: The steps of using the plurality of feedforward microphones to collect and obtain feedforward sound signal spectra from different directions, and using the feedback microphone to collect and obtain feedback sound signal spectra inside the active noise reduction audio device include: Collecting multiple feedforward time-domain sound signals at the current moment through the multiple feedforward microphones; Collecting the feedback time-domain sound signal at the current moment through the feedback microphone; Perform frequency domain conversion on the feedback time domain sound signal and the plurality of feedforward time domain sound signals to obtain and save corresponding frequency spectra of the feedback sound signal and the plurality of feedforward sound signal frequency spectra.

3. The active noise reduction method according to claim 1, wherein: The step of calculating the feedforward frequency response function corresponding to each feedforward microphone comprises: For each of the feedforward microphones: When the active noise reduction function is turned off, a ratio of the feedback sound signal spectrum of the feedback microphone to the feedforward sound signal spectrum of the feedforward microphone is calculated as the feedforward frequency response function of the feedforward microphone.

4. The active noise reduction method according to claim 1, wherein: The reference signal is an output signal of the audio output port.

5. The active noise reduction method according to claim 1, wherein: The step of calculating the weight value corresponding to each feedforward microphone at the current moment according to the correlation between each feedforward microphone and the feedback microphone at the current moment comprises: Calculating the correlation between each of the feedforward microphones and the feedback microphone at the current moment as the signal propagation correlation of each feedforward microphone at the current moment; Summing the signal propagation correlations of all feedforward microphones at the current moment to obtain the system signal propagation correlation at the current moment; The weight value of each feedforward microphone is obtained according to the signal propagation correlation of each feedforward microphone and the system signal propagation correlation at the current moment.

6. The active noise reduction method according to claim 5, characterized in that: The step of obtaining a weight value of each feedforward microphone according to the signal propagation correlation of each feedforward microphone and the system signal propagation correlation at the current moment includes: For each feedforward microphone: The ratio of the signal propagation correlation of the feedforward microphone to the system signal propagation correlation at the current moment is calculated as the weight value of the feedforward microphone.

7. The active noise reduction method according to claim 2, characterized in that: The step of mixing the filtered feedforward sound signal spectra according to the weight value corresponding to each feedforward microphone to obtain the noise-reduced sound signal includes: The filtered feedforward sound signal spectra of each feedforward channel are mixed according to the weight value corresponding to each feedforward microphone to obtain a mixed output frequency domain signal: <h2 style=";text-align:left;direction:ltr">output(T3)=scale1(T3)×ff1<h2 style=";text-align:left;direction:ltr"> req <h2 style=";text-align:left;direction:ltr"> (T3)*ω1(T3)+…+scaleN(T3)×ffN<h2 style=";text-align:left;direction:ltr"> req <h2 style=";text-align:left;direction:ltr"> (T3)*ωN(T3); Among them, output(T3) represents the output frequency domain signal corresponding to the T3th frame, scaleN(T3) represents the weight value corresponding to the Nth feedforward microphone at the T3th frame, ffN req (T3) represents the feedforward sound signal spectrum corresponding to the Nth feedforward microphone at the T3th frame, ωN(T3) represents the parameters of the filter corresponding to the Nth feedforward microphone at the T3th frame, and * represents convolution calculation; Perform inverse Fourier transform on the output frequency domain signal to obtain a noise-reduced sound signal.

8. An active noise reduction audio device, comprising a plurality of feedforward microphones, a feedback microphone and an audio output port, and capable of executing the active noise reduction method according to any one of claims 1 to 7.

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