阅读说明：本技术 降低风噪声的系统和方法 (System and method for reducing wind noise ) 是由 迈克尔·斯梅德加德 大石哲郎 于功强 于 2021-05-11 设计创作，主要内容包括：本公开总体上涉及一种用于降低风噪声的系统和方法。一种系统包括耦合到其上编码有指令的非暂时性计算机可读存储介质的一个或更多个处理器,该指令当被一个或更多个处理器执行时,使得一个或更多个处理器获得在一个时间段期间分别从两个或更多个麦克风生成的信号,该信号表示在该时间段期间由两个或更多个麦克风检测到的声能,确定信号之间的相干性,并基于该相干性确定滤波器。滤波器被配置成降低信号中的一个或更多个中的风噪声。(The present disclosure relates generally to a system and method for reducing wind noise. A system includes one or more processors coupled to a non-transitory computer-readable storage medium having instructions encoded thereon that, when executed by the one or more processors, cause the one or more processors to obtain signals generated from two or more microphones, respectively, during a time period, the signals representing acoustic energy detected by the two or more microphones during the time period, determine a coherence between the signals, and determine a filter based on the coherence. The filter is configured to reduce wind noise in one or more of the signals.)

1. A system, comprising:

one or more processors coupled to a non-transitory computer-readable storage medium having instructions encoded thereon that, when executed by the one or more processors, cause the one or more processors to:

acquiring signals respectively generated from two or more microphones during a time period, the signals being representative of acoustic energy detected by the two or more microphones during the time period;

determining coherence between the signals; and

determining a filter based on the coherence, wherein the filter is configured to reduce wind noise in one or more of the signals.

2. The system of claim 1, wherein to determine the coherency, the non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to:

determining a spectral density of each of the signals; and

cross spectral densities between the signals are determined using the spectral densities.

3. The system of claim 2, wherein to determine the cross-spectral density, the non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to:

smoothing the crossover spectral density using a smoothing factor and a second crossover spectral density generated from signals obtained from the two or more microphones during a second time period, wherein the second time period includes a portion that precedes the time period in time.

4. The system of claim 1, wherein to determine the filter, the non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to:

determining spectral gains between the signals, the spectral gains based on the coherence; and

determining the filter using the spectral gain and a band pass filter.

5. The system of claim 4, wherein to determine the filter using the spectral gain and band pass filters, the non-transitory computer-readable storage medium is encoded with further instructions that, when executed by the one or more processors, cause the one or more processors to:

convolving the spectral gain with the band-pass filter; and

wherein the filter comprises an absolute value of a convolution of the spectral gain and the band pass filter.

6. The system of claim 5, wherein the band pass filter includes desired low and high range cutoff frequencies.

7. The system of claim 1, the non-transitory computer-readable storage medium having encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to:

applying the filters to the signals separately; or

Applying the filter to a processed electrical signal, wherein the processed electrical signal comprises two or more of the signals.

8. An apparatus, comprising:

an input/output interface configured to receive signals from a plurality of microphones; and

one or more processors coupled to a non-transitory computer-readable storage medium having instructions encoded thereon that, when executed by the one or more processors, cause the one or more processors to:

obtaining a first signal generated by a first microphone;

obtaining a second signal produced by a second microphone, wherein the first signal and the second signal correspond to a period of time;

determining coherence between the first signal and the second signal; and

generating a filter based on the coherence, wherein the filter is configured to reduce an amount of wind noise detected by the first microphone and the second microphone.

9. The apparatus of claim 8, wherein to determine the coherency, the non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to:

determining a first spectral density of the first signal;

determining a second spectral density of the second signal; and

determining a cross-spectral density between the first signal and the second signal.

10. The apparatus of claim 9, wherein to determine the cross-spectral density, the non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to:

smoothing the cross-spectral density using a smoothing factor and a second cross-spectral density generated from signals corresponding to the first microphone and the second microphone over a second time period, wherein the second time period includes a portion that precedes the time period in time.

11. The apparatus of claim 10, wherein to generate the filter, the non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to:

determining spectral gains between the signals; and

determining the filter using the spectral gain and a band pass filter.

12. The device of claim 11, wherein to generate the filter using the spectral gain and bandpass filters, the non-transitory computer-readable storage medium is encoded with further instructions that, when executed by the one or more processors, cause the one or more processors to:

convolving the spectral gain with the band-pass filter; and

wherein the filter comprises an absolute value of a convolution of the spectral gain and the band pass filter.

13. The apparatus of claim 12, wherein the band pass filter comprises a cutoff frequency of 150-300 hertz (Hz) and 7000-8000 Hz.

14. The apparatus of claim 13, the non-transitory computer-readable storage medium having encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to: applying the filter to the first signal or the second signal.

15. The apparatus of claim 14, the non-transitory computer-readable storage medium having encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to: applying the filter to a processed electrical signal, wherein the processed electrical signal comprises the first signal and the second signal.

16. A method of reducing wind noise in signals generated by one or more microphones, comprising:

obtaining, via one or more processors, a first signal generated via a first microphone and a second signal generated via a second microphone, wherein the first signal and the second signal correspond to a period of time;

determining, via the one or more processors, coherence between the first signal and the second signal;

determining, via the one or more processors, a filter based on the coherence; and

applying, via the one or more processors, the filter to reduce wind noise detected by the first microphone and the second microphone.

17. The method of claim 16, wherein determining coherence between the first signal and the second signal comprises:

determining a first spectral density of the first signal;

determining a second spectral density of the second signal; and

determining a cross-spectral density of the first signal and the second signal, wherein the cross-spectral density is filtered using a smoothing factor.

18. The method of claim 17, wherein determining the filter comprises:

determining a spectral gain;

convolving the spectral gain with a band pass filter, the band pass filter comprising a frequency band in the speech range; and

generating the filter by taking the absolute value of the convolution between the spectral gain and the band pass filter.

19. The method of claim 18, wherein applying the filter comprises:

convolving the filter with a Fast Fourier Transform (FFT) of the first signal; and

determining an Inverse Fast Fourier Transform (IFFT) of a convolution of the filter and an FFT of the first signal.

20. The method of claim 19, wherein applying the filter comprises:

convolving the filter with a Fast Fourier Transform (FFT) of a processed signal, the processed signal comprising the first signal and the second signal; and

determining an Inverse Fast Fourier Transform (IFFT) of the convolution of the filter and the processed signal.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to audio systems. More particularly, the present disclosure relates to systems and methods for reducing wind noise.

Background

The present disclosure relates generally to audio systems. Audio systems or devices may be used in a variety of electronic devices. For example, an audio system or device may include various microphones and speakers to provide audio feedback to a user of a Virtual Reality (VR), Augmented Reality (AR), or Mixed Reality (MR) system and the ability to communicate with another user or device. For example, an audio system may be used so that a user can speak to another user in real time. In other examples, the audio device may be configured to listen for commands from the user and respond accordingly.

SUMMARY

According to some embodiments, one embodiment of the present disclosure is directed to a system configured to reduce wind noise. For example, an audio system may receive signals generated from one or more microphones. These signals may be representative of the acoustic energy detected by the respective microphones. However, the signals may include wind noise caused by wind or air movement around the respective microphones. The systems and methods described herein are configured to process a signal in order to reduce the amount of wind noise in the signal.

In one embodiment, the system includes one or more processors coupled to a non-transitory computer-readable storage medium having instructions encoded thereon, which when executed by the one or more processors, cause the one or more processors to obtain signals generated from two or more microphones, respectively, during a time period, the signals representing acoustic energy detected by the two or more microphones during the time period, determine coherence between the signals, and determine a filter based on the coherence, wherein the filter is configured to reduce wind noise in one or more of the signals.

In some embodiments, to determine coherence, the non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to determine a spectral density of each signal and determine a cross spectral density between the signals using the spectral densities.

In some embodiments, to determine the cross-spectral density, the non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to smooth the cross-spectral density using the smoothing factor and a second cross-spectral density generated from signals obtained from the two or more microphones during a second time period, wherein the second time period includes a portion that precedes in time the time period. In some embodiments, to determine the filter, the non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to determine a spectral gain between the signals, the spectral gain based on the coherence, and determine the filter using the spectral gain and the band pass filter.

In some embodiments, to determine the filter using the spectral gain and the band pass filter, the non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to convolve the spectral gain with the band pass filter, and wherein the filter comprises absolute values of the convolution of the spectral gain and the band pass filter. In some embodiments, the band pass filter includes desired low and high thresholds and/or ranges of cut-off frequencies. In some embodiments, a non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by one or more processors, cause the one or more processors to apply a filter to a signal alone or to a processed electrical signal, wherein the processed electrical signal includes two or more of the signals.

Another embodiment may be directed to a device (e.g., a head-wearable device). The device may include a first microphone and a second microphone located in different directions. The device may also include one or more processors communicatively coupled to the first microphone and the second microphone. The one or more processors are also coupled to a non-transitory computer-readable storage medium having instructions encoded thereon, which when executed by the one or more processors, cause the one or more processors to obtain a first signal generated by a first microphone, obtain a second signal generated by a second microphone, wherein the first signal and the second signal correspond to a time period, determine a coherence between the first signal and the second signal, and generate a filter based on the coherence, wherein the filter is configured to reduce an amount of wind noise detected by the first microphone and the second microphone.

In some embodiments, to determine coherence, the non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by one or more processors, cause the one or more processors to determine a first spectral density of the first signal, determine a second spectral density of the second signal, and determine a cross spectral density between the first signal and the second signal. In some embodiments, to determine the cross-spectral density, the non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to smooth the cross-spectral density using a smoothing factor and a second cross-spectral density generated from signals corresponding to the first and second microphones over a second time period, wherein the second time period includes a portion that precedes the time period in time.

In some embodiments, to generate the filter, the non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to determine a spectral gain between the signals and determine the filter using the spectral gain and the band pass filter.

In some embodiments, to generate the filter using the spectral gain and bandpass filter, the non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by the one or more processors, cause the one or more processors to convolve the spectral gain with the bandpass filter, wherein the filter comprises absolute values of the convolution of the spectral gain and the bandpass filter. In some embodiments, a non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by one or more processors, cause the one or more processors to apply a filter to the first signal or the second signal. In some embodiments, a non-transitory computer-readable storage medium has encoded thereon further instructions that, when executed by one or more processors, cause the one or more processors to apply a filter to a processed electrical signal, wherein the processed electrical signal comprises a first signal and a second signal.

In another embodiment, a method of reducing wind noise in signals generated by one or more microphones is provided. The method comprises the following steps: obtaining, via one or more processors, a first signal generated via a first microphone and a second signal generated via a second microphone, wherein the first signal and the second signal correspond to a time period; determining, via one or more processors, coherence between the first signal and the second signal; determining, via one or more processors, a filter based on the coherence; and applying, via the one or more processors, a filter to reduce wind noise detected by the first microphone and the second microphone.

In some embodiments, determining the coherence between the first signal and the second signal comprises determining a first spectral density of the first signal, determining a second spectral density of the second signal, and determining a cross spectral density of the first signal and the second signal, wherein the cross spectral density is filtered using a smoothing factor.

In some embodiments, determining the filter includes determining a spectral gain, convolving the spectral gain with a band pass filter, the band pass filter including a frequency band in a speech (speech) range, and generating the filter by taking an absolute value of the convolution between the spectral gain and the band pass filter.

In some embodiments, applying the filter includes convolving the filter with a Fast Fourier Transform (FFT) of the first signal and determining an Inverse Fast Fourier Transform (IFFT) of the convolution of the filter with the FFT of the first signal. In some embodiments, applying the filter includes convolving the filter with a Fast Fourier Transform (FFT) of the processed signal, the processed signal including the first signal and the second signal, and determining an Inverse Fast Fourier Transform (IFFT) of the convolution of the filter and the processed signal.

These and other aspects and implementations are discussed in detail below. The foregoing information and the following detailed description include illustrative examples of various aspects and implementations, and provide an overview or framework for understanding the nature and character of the claimed aspects and implementations. The accompanying drawings are included to provide a further understanding of the various aspects and embodiments, and are incorporated in and constitute a part of this specification.

Brief Description of Drawings

The drawings are not intended to be drawn to scale. Like reference numbers and designations in the various drawings indicate like elements. For purposes of clarity, not every component may be labeled in every drawing. On the attachment

In the figure:

fig. 1 is a block diagram of an audio system in accordance with an illustrative embodiment.

FIG. 2 is a flow chart of a method of reducing wind noise in accordance with an illustrative embodiment.

FIG. 3 is a flow chart of a method of determining coherence between two or more signals in accordance with an illustrative embodiment.

FIG. 4 is a flowchart of a method of determining a filter for wind noise reduction in accordance with an illustrative embodiment.

Fig. 5 is a schematic diagram of a wearable device having an audio system in accordance with an illustrative embodiment.

Detailed Description

Referring generally to the drawings, systems and methods for an audio system are shown, according to some embodiments. In some embodiments, the audio system includes processing circuitry configured to connect (e.g., communicatively couple) to a peripheral device. The peripheral device may include a first microphone and a second microphone. In some embodiments, the peripheral device may include additional microphones. The microphone is configured to sense or detect acoustic energy and generate a signal representative of the sensed or detected acoustic energy.

The processing circuit is configured to receive a first signal from the first microphone and a second signal from the second microphone. The processing circuit is configured to execute a wind reduction algorithm configured to reduce an amount of wind noise present within (e.g., detected by) the first and second signals. The wind reduction algorithm includes receiving a first signal and a second signal, determining a coherence between the first signal and the second signal, determining a filter based on the coherence, and applying the filter. In this way, the audio system is able to filter out wind noise captured by the first and second microphones. In particular, wind present in the environment may cause turbulence in or around the physical structure of the first and second microphones, resulting in wind noise appearing in the respective signals. The audio system is configured to determine coherence between a first channel (e.g., a first signal) and a second channel (e.g., a second signal) (e.g., assuming that wind noise between the channels is uncorrelated due to differences in turbulence generated around different microphones), and filter out the wind noise based on the coherence. In some embodiments, the audio system may filter out wind noise based on coherence using spectral weighting, which may adjust the amplitude of the signal and maintain phase information. Thus, the audio system provides an improvement over existing systems by filtering wind noise based on coherence, which improves audio quality.

Referring now to fig. 1, a block diagram of an audio system 100 is shown. The audio system 100 includes a processing circuit 102 configured to communicate with a peripheral device 101. In some embodiments, the audio system 100 may be integrated in various forms, such as glasses, mobile devices, personal devices, head mounted displays, wireless headsets (headsets), or headphones, and/or other electronic devices.

The peripheral device 101 includes a first microphone 110 and a second microphone 111. In some embodiments, peripheral device 101 may include additional (e.g., 3, 4, 5, 6, or more) microphones. Microphones 110 and 111 are configured to sense or detect acoustic energy and generate corresponding signals (e.g., electrical signals) indicative of the acoustic energy. In some embodiments, the acoustic energy may include speech, wind noise, ambient noise, or other forms of audible energy. In some embodiments, the peripheral device 101 may also include one or more speakers 112 or headphones configured to generate sound.

The processing circuit 102 may include a processor 120, a memory 121, and an input/output interface 122. In some embodiments, the processing circuit 102 may be integrated with various electronic devices. For example, in some embodiments, the processing circuit 102 may be integrated with a wearable device such as a head-mounted display, a smart watch, wearable goggles, or wearable glasses. In some embodiments, the processing circuit 102 may be integrated with a gaming console, personal computer, server system, or other computing device. In some embodiments, the processing circuit 102 may also include one or more processors, microcontrollers, Application Specific Integrated Circuits (ASICs), or circuits integrated with the peripherals 101 and designed to cause or assist the audio system 100 to perform any of the steps, operations, processes, or methods described herein.

The processing circuitry 102 may include one or more circuits, processors 120, and/or hardware components. The processing circuit 102 may implement any logic, functionality, or instructions to perform any of the operations described herein. The processing circuitry 102 may include any type and form of memory 121 configured to store executable instructions that may be executed by any circuit, processor, or hardware component. The executable instructions may be of any type, including applications, programs, services, tasks, scripts, library processes, and/or firmware. In some embodiments, memory 121 may include a non-transitory, computable readable medium coupled to processor 120 and storing one or more executable instructions configured to, when executed by processor 120, cause processor 120 to perform or implement any of the steps, operations, processes, or methods described herein. In some embodiments, the memory 121 is configured to also store information about the local location of each peripheral device, filter information, a smoothing factor, a constant value, or historical filter information in a database.

In some embodiments, input/output interface 122 of processing circuitry 102 is configured to allow processing circuitry 102 to communicate with peripheral device 101 and other devices. In some embodiments, input/output interface 122 may be configured to allow a physical connection (e.g., a wired or other physical electrical connection) between processing circuitry 102 and peripheral device 101. In some embodiments, the input/output interface 122 may include a wireless interface configured to allow wireless communication between the peripheral device 101 (e.g., a microcontroller on the peripheral device 101 connected to leads of one or more coils) and the processing circuit 102. The wireless communication may include bluetooth, a Wireless Local Area Network (WLAN) connection, a Radio Frequency Identification (RFID) connection, or other types of wireless connections. In some embodiments, the input/output interface 122 also allows the processing circuit 102 to connect to the internet (e.g., via a wired or wireless connection) and/or a telecommunications network. In some embodiments, input/output interface 122 also allows processing circuit 102 to connect to other devices, such as a display or other electronic devices that may receive information received from peripheral device 101.

Referring now to FIG. 2, a flowchart of a method 200 of reducing wind noise is shown in accordance with an illustrative embodiment. In operation 201, signals from two or more microphones are received. The audio system may receive multiple signals from individual microphones or access multiple signals from individual microphones from a buffer, database, or other storage medium. In some embodiments, the signals include a first signal generated by a first microphone and a second signal generated by a second microphone.

In operation 202, coherence between signals from two or more microphones is determined. For example, the audio system may determine coherence between the first signal and the second signal. Coherence between signals can be used to check the relationship between signals. For example, coherence can be used to check for and correct wind noise or noise caused by uncorrelated air motion detected by individual microphones. The uncorrelated portion of the signal may indicate that the signal includes wind noise. In some embodiments, the audio system may generate a filter configured to reduce the amplitude of the uncorrelated portions of the signals, thereby filtering out wind noise. Examples of determining and using coherence in order to reduce wind noise in a signal are discussed in further detail below.

In operation 203, a filter is determined or generated based on coherence between signals from two or more microphones. For example, in some embodiments, the audio system may determine the filter by determining a spectral gain between the signals (e.g., the first and second signals) and convolving the spectral gain with a band pass filter having a frequency band within the audible range (e.g., 200 Hz-8000 Hz). In this way, the band pass filter cuts off and filters out frequencies outside the audible range, and the spectral gain adjusts the amplitude of different portions of the frequency band that may be due to wind noise of the band pass filter (e.g., due to a lack of correlation between the first and second signals).

In operation 204, a filter is applied to reduce wind noise. In some embodiments, the audio system may apply a filter to each signal. For example, the audio system may apply the filters directly to the first and second signals. As an example, the audio system may convolve the filter with a Fast Fourier Transform (FFT) of the first signal and Inverse Fast Fourier Transform (IFFT) the result to generate the filtered first signal. Similarly, the audio system may convolve the filter with the FFT of the second signal and IFFT the result to generate a filtered second signal. The filtered first and second signals may then be further processed and/or transmitted.

In some embodiments, the signal may be first processed into one or more processed signals, and a filter may be applied to the one or more processed signals. For example, in some embodiments, the first and second signals may be processed with a beamforming algorithm, an Acoustic Echo Cancellation (AEC) algorithm, an Active Noise Control (ANC) algorithm, and/or other algorithms that may turn the first and second signals into a single processed signal. The audio system may apply a filter to the single processed signal in order to reduce wind noise in the single processed signal. For example, an FFT of the single processed signal may be convolved with a filter, and the resulting IFFT may be used to produce a filtered single processed signal.

Referring now to fig. 3, a flow diagram of a method 300 of determining coherence between signals from two or more microphones is shown in accordance with an illustrative embodiment. In operation 301, spectral densities of signals from two or more microphones are determined. In some embodiments, the audio system 100 may process or sample signals. For example, in some embodiments, the audio system may process a signal having a particular number of samples (e.g., 1024 samples), time stamp the signal (e.g., the samples begin at time k), overlap with a previous signal (e.g., 512 samples may overlap with corresponding signals from two or more microphones at a previous time), and have been sampled at a particular rate (e.g., 48 kilohertz). For example, the signals may include a first signal generated by a first microphone and a second signal generated by a second microphone. At a particular time (e.g., k), over a particular number of samples (e.g., 1024), a first FFT (e.g., discrete time FFT) of the first signal may be computed, and a second FFT (e.g., discrete time FFT) of the second signal may be computed. In some embodiments, the spectral density (Φ) of the first signal may be calculated by convolving the first FFT with the complex conjugate of the first FFT_ii(w, k)) (e.g., where w equals the number of frequency bins (bins) and k equals the time stamp), and the spectral density of the second signal (Φ) may be calculated by convolving the second FFT with the complex conjugate of the second FFT_jj(w, k)). In other examples, other computational techniques may be used to calculate the spectral densities of the first and second signals.

In operation 302, cross spectral densities of signals from two or more microphones are determined. For example, in some embodiments, the cross-spectral density (Φ) between the first signal and the second signal_ij(w, k)) may be calculated by convolving the first FFT with the complex conjugate of the second FFT. In other examples, other computational techniques may be used to calculate the spectral densities of the first and second signals. For example, in some embodiments, equation (1) may be used to account forCalculating or estimating cross-spectral density (phi)_ij(w，k))：

(1) Φij(w，k)＝λ(w，k-1)*Φij(w，k-1)+(1-λ(w，k-1))*Xi*conj(Xj)，

Where λ (w, k-1) is the smoothing factor from an earlier time (e.g., immediately prior), Φ ij (w, k-1) is the cross-spectral density between signals from earlier times, Xi is the FFT of the signal corresponding to i (e.g., 1, 2, … …, etc.), and Xj is the FFT of the signal corresponding to j (e.g., 1, 2, … …, etc.). In some embodiments, the smoothing factor allows smoothing (e.g., exponential smoothing or filtering) in the cross-spectral density. The calculation and updating of the smoothing factor is discussed in further detail herein with reference to operation 303.

In operation 303, coherence between the signals is determined. In some embodiments, the audio system may determine a complex coherence spectrum (complex coherence spectrum) between the signals. For example, the coherence spectrum can be calculated as shown in equation (2):

in other examples, other computing techniques may be used to compute coherence, coherence spectrum, or complex coherence spectrum between signals from the microphones.

In some embodiments, the smoothing factor (λ (w, k)) corresponding to the current time may also be updated in operation 303. In some embodiments, the smoothing factor may be calculated as shown in equation (3).

(3) λ(w，k)＝∝(w)-β(w)*|Γ(w，k)|.

Equation (3) shows that the smoothing factor (λ (w, k)) for the current time (k) may be calculated by multiplying the constant beta (β) by the absolute value of the coherence spectrum Γ (w, k) and subtracting the product from the second constant alpha (—). The constants beta and alpha may be determined experimentally and manually entered or updated in the audio system. In some embodiments, alpha may be an optimization constant determined based on microphone performance. In some embodiments, beta may be an optimization constant determined based on microphone performance.

Referring now to FIG. 4, a flow diagram of a method 400 of determining or generating a wind noise reducing filter is shown in accordance with an illustrative embodiment. In operation 401, a spectral gain (G (w, k)) of a signal is calculated. In some embodiments, the audio system calculates the spectral gain according to equation (4).

(4) G(w，k)＝Φij(w，k)/((Φii(w，k)*Φjj(w，k))/2)

The spectral gain G (w, k) may represent the signal-to-signal plus noise ratio (S/(S + N)) between the signals. In other embodiments, other calculation techniques may be used to calculate the spectral gain.

In operation 402, the spectral gain is convolved with the band pass filter and the absolute value of the product is taken to generate the filter. The audio system may convolve or calculate the convolution between the spectral gain and a band pass filter stored in memory. The band pass filter may have a frequency band in the audible or speech range. For example, in some embodiments, the band pass filter may have a lower cutoff frequency of 200 hertz (Hz) (e.g., or in the range of 150Hz-300 Hz) and a higher cutoff frequency of 8000Hz (e.g., or in the range of 7000Hz-9000 Hz). As described above, the spectral gain represents or represents the signal to signal plus noise ratio (S/(S + N)), so the convolution of the band pass filter and the spectral gain produces a filter having a frequency band in the audible or speech range with an adjusted amplitude that is used to filter out wind noise in the frequency band. In other words, since the spectral gain is based on correlation or coherence between signals, portions or bands of incoherence between signals (e.g., due to the presence of wind noise) will be filtered out or reduced.

Referring now to fig. 5, a schematic diagram 500 of a wearable device having an audio system is shown, according to an illustrative embodiment. Diagram 500 includes a wearable device 502 (e.g., glasses or eyeboxes configured to be secured to a user's head) and a wind vector 503 passing through and impinging on wearable device 502. Wearable device 502 includes first microphone 110, second microphone 111. In some embodiments, wearable device 502 may include an additional microphone. Wearable device 502 also includes two speakers 112a and 112 b. In some embodiments, wearable device 502 may also include a display.

In one example, a user may wear wearable device 502 and be in an environment (e.g., represented by wind vector 503) where wind is present (e.g., or moving air relative to the device due to the user's motion). Wind or moving air may cause turbulence in or around the ports or other structures of the microphones 110 and 111, thereby causing undesirable wind noise in the signals produced by the microphones 110 and 111. For example, a user may be jogging outdoors and the substantial wind noise created by moving air may prevent the user from being able to talk to a person over a cellular network, issue commands to a virtual assistant, or otherwise utilize audio features. However, the audio system 100 may utilize a wind reduction algorithm to reduce wind noise in the signal by filtering the wind noise from the signal based on the coherence between the first signal generated by the first microphone 110 and the second signal generated by the second microphone 111, thereby improving the performance of the wearable device.

Having now described some illustrative embodiments, it is to be understood that the foregoing is illustrative and not limiting, and has been given by way of example. In particular, although many of the examples presented herein involve specific combinations of method acts or system elements, those acts and those elements may be combined in other ways to accomplish the same objectives. Acts, elements and features discussed in connection with one embodiment are not intended to be excluded from a similar role in other embodiments or implementations.

The hardware and data processing components used to implement the various processes, operations, illustrative logic, logic blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose single-or multi-chip processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some embodiments, certain processes and methods may be performed by circuitry that is specific to a given function. The memory (e.g., memory units, storage devices, etc.) may include one or more devices (e.g., RAM, ROM, flash memory, hard disk storage, etc.) for storing data and/or computer code to complete or facilitate the various processes, layers, and modules described in this disclosure. The memory may be or include volatile memory or non-volatile memory, and may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described in this disclosure. According to an exemplary embodiment, the memory is communicatively connected to the processor via the processing circuitry and includes computer code for performing (e.g., by the processing circuitry and/or the processor) one or more processes described herein.

The present disclosure contemplates methods, systems, and program products on any machine-readable media for accomplishing the various operations. Embodiments of the present disclosure may be implemented using an existing computer processor, or by a special purpose computer processor of an appropriate system introduced for this or other purposes, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions comprise, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," "having," "containing," "involving," "characterized by … …," "characterized by," and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and alternative implementations consisting only of the items listed thereafter. In one embodiment, the systems and methods described herein are comprised of one, each combination of more than one, or all of the described elements, acts, or components.

Any reference herein to embodiments or elements or acts of the systems and methods in the singular may also include embodiments comprising a plurality of these elements, and any reference herein to any embodiment or element or act in the plural may also include embodiments comprising only a single element. References in the singular or plural form are not intended to limit the presently disclosed systems or methods, their components, acts, or elements to a single or more configuration. References to any action or element based on any information, action, or element may include implementations in which the action or element is based, at least in part, on any information, action, or element.

Any implementation disclosed herein may be combined with any other implementation or embodiment, and references to "an implementation," "some implementations," "one implementation," and so forth are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described in connection with the implementation may be included in at least one implementation or embodiment. These terms, as used herein, do not necessarily all refer to the same implementation. Any implementation may be combined with any other implementation, including or exclusively, in any manner consistent with aspects and implementations disclosed herein.

Where technical features in the figures, detailed description or any claims are followed by reference signs, the reference signs have been included to increase the intelligibility of the figures, detailed description and claims. Thus, neither the reference signs nor their absence are intended to have any limiting effect on the scope of any claim elements.

The systems and methods described herein may be embodied in other specific forms without departing from the characteristics thereof. Additional descriptions of relative parallel, perpendicular, vertical, or other orientations or orientations include variations within +/-10% or +/-10 degrees of purely vertical, parallel, or perpendicular orientations. Unless otherwise expressly stated, reference to "about", "substantially" or other terms of degree includes a variation of +/-10% of a given measurement, unit or range. The coupling elements may be directly electrically, mechanically or physically coupled to each other or with intervening elements. The scope of the systems and methods described herein is, therefore, indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

The term "coupled" and variations thereof includes two members directly or indirectly connected to each other. Such a connection may be stationary (e.g., permanent or fixed) or movable (e.g., removable or releasable). Such joining may be achieved with the two members being directly connected or interconnected, with the two members being interconnected using separate intermediate members and any additional intermediate members, or with the two members being interconnected using intermediate members integrally formed as a single unitary body with one of the two members. If "coupled" or variations thereof are modified by additional terms (e.g., directly coupled), then the general definition of "coupled" provided above is modified by the plain-language meaning of the additional terms (e.g., "directly coupled" refers to the joining of two members without any separate intermediate members), resulting in a narrower definition than the general definition of "coupled" provided above. This coupling may be mechanical, electrical or fluid.

References to "or" may be construed as inclusive, and thus any term described using "or" may mean any one of the singular, the plural, and all of the recited terms. Reference to "at least one of a' and B" may include only "a", only "B", and both "a" and "B". Such references used with "including" or other open terms may include additional items.

Modifications to the components and acts described, such as variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc., may be made without materially departing from the teachings and advantages of the subject matter disclosed herein. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the elements and operations disclosed without departing from the scope of the present disclosure.

The component positions referred to herein (e.g., "top," "bottom," "above," "below") are merely used to describe the orientation of the various components within the figures. According to other exemplary embodiments, the orientation of the various elements may be different, and such variations are intended to be encompassed by the present disclosure.