Multi-purpose Microphone in Acoustic Equipment

Abstract

This document describes a method that includes: receiving an input signal representing audio captured by a sensor disposed in an active noise reduction (ANR) device; determining, by one or more processing devices, that the ANR device is operating in a first operating mode; and in response, applying a first gain to the input signal to generate a first amplified input signal. The method further includes: determining, by the one or more processing devices, that the ANR device is operating in a second operating mode different from the first operating mode; and in response, applying a second gain to the input signal to generate a second amplified input signal, where the second gain is different from the first gain. The method further includes: processing the first amplified input signal or the second amplified input signal to generate an output signal, and generating an audio output based on the output signal by an acoustic transducer.

Description

Technical Field

[0001] This specification generally relates to acoustic devices including multi-purpose microphones. Background Art

[0002] Acoustic devices are used in a variety of environments and for various purposes, including entertainment purposes (such as listening to music), production purposes (such as telephone calls), and professional purposes (such as aviation communication or studio monitoring). Different purposes may require an acoustic device to detect sounds within the environment, such as by using a microphone. For example, to allow voice communication or speech recognition, an acoustic device may use a microphone to detect a user's voice within the environment. Other acoustic devices may include noise reduction or noise cancellation features that cancel ambient noise detected in the environment. Summary of the Invention

[0003] In one aspect, this document describes a method that includes: receiving an input signal representing audio captured by a sensor disposed in an active noise reduction (ANR) device; determining, by one or more processing devices, that the ANR device is operating in a first operating mode; and in response, applying a first gain to the input signal to generate a first amplified input signal. The method further includes: determining, by one or more processing devices, that the ANR device is operating in a second operating mode different from the first operating mode; and in response, applying a second gain to the input signal to generate a second amplified input signal, where the second gain is different from the first gain. The method further includes: processing the first amplified input signal or the second amplified input signal to generate an output signal, and generating an audio output based on the output signal by a sound transducer.

[0004] In another aspect, this document describes an automatic noise reduction (ANR) device that includes: one or more sensors for capturing audio; at least one amplifier that amplifies an input signal representing audio captured by the one or more sensors; and a controller that includes one or more processing devices. The controller is configured to determine that the ANR device is operating in a first operating mode and, in response, apply a first gain to the input signal to generate a first amplified input signal. The controller is further configured to determine that the ANR device is operating in a second operating mode different from the first operating mode and, in response, apply a second gain different from the first gain to the input signal to generate a second amplified input signal, and process the first amplified input signal or the second amplified input signal to generate an output signal. The ANR device further includes a sound transducer for generating an audio output based on the output signal.

[0005] In another aspect, this document describes one or more non-transitory machine-readable storage devices that store machine-readable instructions that cause one or more processing devices to perform various operations. These operations include: receiving an input signal representing audio captured by a sensor disposed in an active noise reduction (ANR) device; determining that the ANR device is operating in a first operating mode; and in response, applying a first gain to the input signal to generate a first amplified input signal. These operations further include: determining that the ANR device is operating in a second operating mode different from the first operating mode; and in response, applying a second gain different from the first gain to the input signal to generate a second amplified input signal. These operations also include: processing the first amplified input signal or the second amplified input signal to generate an output signal; and causing a sound transducer to generate an audio output based on the output signal.

[0006] Specific implementations of the above aspects may include one or more of the following features.

[0007] The first operating mode of the ANR device may include a voice communication mode, and the second operating mode of the ANR device may include a noise reduction mode. The sensor may include a microphone of the ANR device. The output signal may include a drive signal for the sound transducer. The first amplified input signal or the second amplified input signal may be processed using at least one compensator to generate a drive signal for the sound transducer. The drive signal may include an anti-noise signal. A second input signal representing audio captured by a second sensor disposed in the ANR device may be received, and the second input signal may be combined with the first amplified input signal or the second amplified input signal to produce a combined input signal. The combined input signal may be processed using at least one compensator to generate an output signal for the ANR device. The output signal may include an anti-noise signal. A second input signal representing audio captured by a second sensor disposed in the ANR device may be received, and the second input signal may be processed together with the first amplified input signal or the second amplified input signal to direct a beam toward the mouth of a user of the ANR device to generate a main signal. Additionally, the corresponding amplified input signal and the second input signal may be processed to direct a null toward the mouth of a user of the ANR device to generate a reference signal, and the reference signal may be used as a noise reference to process the main signal to generate an output signal for the ANR device. The beam or the null may be directed using one of the following: near-field beamforming techniques or delay-and-sum beamforming techniques.

[0008] These and other aspects, features, and specific implementations may be represented as a method, apparatus, system, component, program product, method of performing a business, apparatus or step for performing a function, and in other ways, and will become apparent from the following description (including the claims). Description of the Drawings

[0009] Figure 1 Is a perspective view of an exemplary headset assembly.

[0010] Figure 2 Is a left side view of an exemplary headset assembly.

[0011] Figure 3 And Figure 4 Is a block diagram of an exemplary system for processing signals received from a multi-purpose microphone.

[0012] Figure 5 Is a block diagram of an exemplary system for implementing a beamforming process.

[0013] Figure 6 Is a flowchart of an exemplary process for processing signals received from a multi-purpose microphone.

[0014] Figure 7 Is a block diagram of an example of a computing device.

[0015] Like reference numerals in the various drawings indicate like elements. Detailed Description

[0016] Acoustic devices (such as headphones, headsets, or other acoustic systems) can include various features related to detecting sounds within the surrounding environment. Generally, one or more microphones included in the acoustic device are used to detect these sounds. The acoustic signals generated by the microphones are processed by the acoustic device to implement various features. For example, in some cases, the acoustic device can process the acoustic signals to isolate and detect the user's speech to implement speech communication or speech recognition features. In some cases, the acoustic device can process the acoustic signals to generate anti-noise signals to implement active noise reduction (ANR) features. The features included in the acoustic device can have different signal level requirements for the acoustic signals detected by the microphones.

[0017] Aspects of the present disclosure relate to acoustic devices having one or more multi-purpose microphones. Each multi-purpose microphone can generate acoustic signals that can be processed to implement two or more features of the acoustic device, such as communication features and ANR features, etc. In some cases, the acoustic device can determine the operating mode of the device (or a connected device, such as a mobile phone), and can adjust the gain or another parameter applied to the acoustic signals based on the operating mode. In this way, when compared to an acoustic device that uses a separate microphone for each feature, the acoustic device can optimize the processing of the acoustic signals according to the signal requirements of the individual features, while reducing the cost, power consumption, and space requirements of the acoustic device.

[0018] We use the term "multi-purpose microphone" broadly to include any analog microphone, digital microphone, or other acoustic sensor included in an acoustic device and configured to generate an acoustic signal for implementing two or more features of the acoustic device, including but not limited to communication features and ANR features. Conversely, we sometimes use the term "single-purpose microphone" or "dedicated microphone" to refer to a microphone configured to generate an acoustic signal for implementing a specific feature of an acoustic device.

[0019] The techniques described herein can include headsets, earphones, hearing aids, or other personal acoustic devices, as well as acoustic systems such as can be applied to or operate in home, office, or automotive environments. Throughout this disclosure, the terms "headset," "earphone," "earbud," and "earphone set" may be used interchangeably, and using one term in place of another is not intended to make a distinction unless the context clearly indicates otherwise. Additionally, the aspects and examples disclosed herein are applicable to a variety of form factors, such as in-ear transducers or earbuds, on-ear or over-ear headphones, or audio devices worn near the ear and radiating sound energy into or towards the ear (including open-ear audio devices worn on a user's head or shoulder), among others.

[0020] The examples disclosed herein can be coupled to other systems or arranged to connect to other systems via wired or wireless means, or can be independent of any other system or device. The examples disclosed herein can be combined with other examples in any manner consistent with at least one of the principles disclosed herein, and references to "example," "some examples," "alternative examples," "various examples," "one example," etc. are not necessarily mutually exclusive and are intended to indicate that the particular feature, structure, or characteristic described may be included in at least one example. The occurrence of such terms herein does not necessarily all refer to the same example.

[0021] Figure 1 A set of headphones 100 is shown, which includes two earcups, namely, a right earcup 102 and a left earcup 104, which are respectively coupled to a right yoke assembly 108 and a left yoke assembly 110 and interconnected by a headband 106. The right earcup 102 and the left earcup 104 respectively include a right over-ear earpad 112 and a left over-ear earpad 114. While the exemplary headphones 100 are shown as having earcups with over-ear earpads that fit around or over a user's ear, in other examples, these earpads can be located on the ear, or can include an earbud portion that protrudes into a part of the user's ear canal, or can include an alternative physical arrangement. As discussed in more detail below, either or both of the earcups 102, 104 can include one or more microphones, some or all of which can be multi-purpose microphones. While Figure 1The exemplary headset 100 shown includes two earpieces, but some examples may include only a single earpiece for only one side of the head. Additionally, although Figure 1 the headset 100 shown includes a headband 106, other examples may include different support structures to hold one or more earpieces (e.g., earcups, in-ear structures, etc.) close to the user's ears. For example, earbuds may include a shape and / or material configured to hold the earbuds within a portion of the user's ear.

[0022] Figure 2 The headset 100 is shown from the left side and details of the left earcup 104 are shown, which includes a pair of front microphones 202 and rear microphones 206. The pair of front microphones can be near the front edge 204 of the earcup, and the rear microphones can be near the rear edge 208 of the earcup. The right earcup 102 can additionally or alternatively have a similar arrangement of front and rear microphones, but in an example, the two earcups can have different arrangements in terms of the number or placement of microphones. Some or all of the front microphones 202 or rear microphones 206 can be multi-purpose microphones for implementing two or more features of the headset 100. In some cases, one of the front microphones 202 can be a multi-purpose microphone, and each of the remaining microphones 202, 206 can be dedicated to a specific feature of the headset 100.

[0023] In various examples, the headset 100 can have more, fewer, or no front microphones 202, and can have more, fewer, or no rear microphones 206, as long as the headset includes at least one multi-purpose microphone. In some cases, the headset 100 can include one or more multi-purpose or dedicated microphones inside the right earcup 102 or the left earcup 104 or both. Although microphones are shown in the various figures and labeled with reference numerals (such as reference numerals 202, 206), in some examples, the visible elements shown in the figures can represent acoustic ports through which acoustic signals enter to ultimately reach the microphones 202, 206, which can be internal and not visible from the outside. In an example, one or more of the microphones 202, 206 can be adjacent to the inside of the acoustic port or can be a distance away from the acoustic port, and can include a sound waveguide between the acoustic port and the associated microphone.

[0024] Figure 3An exemplary signal processing system 300 is shown that is configured to process signals received from a multi-purpose microphone 302. The multi-purpose microphone 302 can be an analog microphone, a digital microphone, or another acoustic sensor configured to generate an acoustic signal representative of sound in the environment surrounding the acoustic device. For example, the multi-purpose microphone 302 can be one of the front microphones 202 of the headset 100. For clarity, the system 300 is depicted with a single multi-purpose microphone 302. However, in some cases, the system 300 can include two or more multi-purpose microphones or at least one multi-purpose microphone and one or more dedicated microphones. For example, the system 300 can include two or more multi-purpose microphones operating in combination with the multi-purpose microphone 302. Additionally, in some examples, a system such as the headset 100 can include two or more signal processing systems 300, each signal processing system being configured to process signals received from one or more multi-purpose microphones.

[0025] As Figure 3 shown, the multi-purpose microphone 302 can be coupled to an amplifier 304. The amplifier 304 can apply a gain G to the signal generated by the multi-purpose microphone 302. For example, the gain applied by the amplifier 304 can be an analog gain, and the amplifier 304 can be a variable gain amplifier (VGA).

[0026] The output of the amplifier 304 can be coupled to a switch 306 that is configured to selectively couple the amplifier output to one or more digital signal processors (DSPs) 308A - 308C (collectively 308). The switch 306 can be implemented as a hardware switch, a software switch, a combination of both hardware and software components, etc. In some cases, the DSP 308 selectively coupled to the amplifier output by the switch 306 is selected based on input from a user. In some cases, the DSP 308 selectively coupled to the amplifier output by the switch 306 is automatically selected by the acoustic device. For example, the selection of one or more DSPs 308 can be based on time, the location of the acoustic device, one or more characteristics of the amplifier output, etc.

[0027] In some cases, the signal processing system 300 can include one or more analog-to-digital converters (ADCs) before or after the switch 306 to convert the analog output of the amplifier 304 into a digital input for the DSP 308. In the case where the amplifier 304 applies a digital gain to the signal generated by the multi-purpose microphone 302, the ADC can be included before the amplifier 304.

[0028] The DSP 308 processes the signals generated by the multi-purpose microphone 302 to produce corresponding outputs 310A - 310C (collectively 310). For example, the signals can be processed to implement one or more features of the acoustic device. In some cases, each DSP in the DSP 308 can be associated with a different feature of the acoustic device. For example, DSP 308A can implement the ANR feature of the acoustic device, while DSP 308B can implement the communication feature of the acoustic device. In some cases, some or all of the DSPs in the DSP 308 can be combined such that a single DSP implements two or more features of the acoustic device. Examples of such DSPs are described in U.S. Patents 8,073,150 and 8,073,151, which are hereby incorporated by reference in their entirety.

[0029] The features of the acoustic device implemented by the DSP 308 can include various features such as ANR features, voice communication features, "talk-through" or "hear-through" features, etc. Further descriptions of these features are provided below.

[0030] In some cases, the acoustic device incorporating the signal processing system 300 can be an ANR system, where one or more of the DSPs 308 implement the ANR feature. Generally speaking, an ANR system can include an electroacoustic or electromechanical system that is configured to cancel at least some of the undesired noise (commonly referred to as the primary noise) based on the superposition principle. For example, the ANR system can identify the amplitude and phase of the primary noise and generate another signal (commonly referred to as the "antinoise signal") with an amplitude approximately equal and a phase opposite. The antinoise signal can then be combined with the primary noise such that both are substantially canceled at the desired location. As used herein, the term "substantially cancel" can include reducing the "canceled" noise to a specific level or an acceptable tolerance and does not require complete elimination of all noise. Thus, one or more DSPs 308 of the signal processing device 300 can implement the ANR feature of the acoustic device by processing the primary noise signal (e.g., the signal generated by the multi-purpose microphone 302) to produce an antinoise signal for noise cancellation (e.g., one or more of the outputs 310). As described herein, the ANC feature can be used to attenuate a wide range of noise signals, including, for example, broadband noise and / or low-frequency noise that may not be easily attenuated using passive noise control systems.

[0031] In some cases, an acoustic device incorporating the signal processing system 300 can implement one or more communication features. Specifically, in some cases, the communication feature can be a voice communication feature. The voice communication feature can generate a voice signal representative of the voice of the user of the acoustic device or another user. The voice signal can be used locally by the acoustic device or transmitted to another device coupled to the acoustic device, such as a mobile device, etc. The voice signal can be used for voice communication (such as in a phone call), or for voice recognition (such as for speech-to-text or communicating with a virtual personal assistant), etc. In some cases, the communication feature can generate a signal representing a sound other than voice (such as music), which can also be used locally or transmitted to another device for communication, such as in a phone call. Thus, one or more DSPs 308 of the signal processing device 300 can implement the communication feature of the acoustic device by processing the signal generated by the multi-purpose microphone 302 to generate a voice signal or other signal (e.g., one or more outputs 310) for voice recognition, call purposes, etc. In some cases, implementing the communication feature can also include a beamforming process that uses signals captured by one or more additional multi-purpose microphones or dedicated microphones. The beamforming process is described in further detail below with reference to Figure 5 The beamforming process is described in further detail below with reference to

[0032] In some cases, an acoustic device incorporating the signal processing system 300 can implement a feature that can be referred to as a "through-talk" or "through-listen" mode. Similarly, the acoustic device can be an ANR system; however, in this mode, at least a portion of the signal captured by the multi-purpose microphone 302 is not cancelled. In this mode, the microphone (e.g., multi-purpose microphone 302) can be used to detect external sounds that the user may want to hear, and the acoustic device can be configured to generate a signal (e.g., one or more outputs 310) that conveys these sounds to be reproduced by the transducer for the user. In some specific implementations, signals captured by multiple sensors (e.g., one or more additional multi-purpose microphones or dedicated microphones) can be used (e.g., using the beamforming process) to focus on another source, such as the user's voice or ambient sound. In some specific implementations, the acoustic device can allow multi-mode operation including a through-listen mode in which the ANR function can be turned off or at least reduced in at least one frequency range to allow relatively broadband ambient sound to reach the user. In some specific implementations, the acoustic device can also be used to shape the frequency response of the signal passing through the earphone. For example, one or more DSPs 308 of the signal processing system 300 can be used to change the acoustic experience of the earbud blocking the ear canal to an experience where ambient sounds (such as the user's own voice) sound more natural to the user.

[0033] Each of the features of the above-described acoustic device (e.g., ANR feature, communication feature, "through-talk" or "through-listen" feature, etc.) may have different signal level requirements. For example, achieving the communication feature of an acoustic device may require a higher signal-to-noise ratio (SNR) than that required to achieve the ANR feature of the acoustic device. Generally speaking, applying gain to an acoustic signal increases the SNR; however, as the gain increases, the likelihood of clipping the acoustic signal also increases. We use the term "clipping" extensively to describe the waveform distortion that occurs when an amplifier is overdriven. For example, clipping of an acoustic signal may occur when the amplifier attempts to deliver a voltage or current higher than its maximum capacity (e.g., to apply a high gain value). Thus, the different signal level requirements of the various features of an acoustic device can be related to the perceived objectionability level of clipping in the implementation of each feature. For example, a user may perceive clipping to be more objectionable in the implementation of the ANR feature compared to the implementation of the communication feature of the acoustic device. This may be because clipping the acoustic signal in implementing the ANR feature can produce acoustic artifacts (e.g., sound noise, screeching, etc.) that are uncomfortable or otherwise unwelcome to the user.

[0034] To accommodate the different signal requirements of different features, system 300 can determine the operating mode of the acoustic device (or the connected device) and can adjust the gain (or another parameter) applied by the amplifier. For example, when implementing the communication feature of an acoustic device where clipping is less objectionable, a higher gain can be applied to the acoustic signal to increase the SNR. Conversely, when implementing the ANR feature of an acoustic device where clipping is more objectionable, a lower gain can be applied to the acoustic signal to achieve a high SNR while ensuring that clipping does not occur too frequently in the normal use of the acoustic device.

[0035] In some cases, two separate DSPs can be used to implement the ANR feature and the communication feature respectively. For example, referring again to Figure 3 , DSP 308A can implement the ANR feature of the acoustic device, while DSP 308B can implement the communication feature of the acoustic device. In this example, the gain G applied by amplifier 304 can be modified according to the operating mode of the acoustic device. For example, in the case where switch 306 selectively couples the amplifier output to DSP 308A to operate the acoustic device in ANR mode, the gain G can be set to a value suitable for the ANR feature, thereby increasing the SNR while limiting the occurrence of objectionable clipping. However, in the case where switch 306 selectively couples the amplifier output to DSP 308B to operate the acoustic device in communication mode, the gain G can be set to a higher value suitable for the communication feature, thereby further increasing the SNR.

[0036] In another example, again, DSP 308A can implement the ANR feature of the acoustic device, while DSP 308B can implement the communication feature of the acoustic device. However, in this example, the gain G can be fixed at a value suitable for the ANR feature, thereby increasing the SNR while limiting the occurrence of objectionable clipping. Thus, when switch 306 selectively couples the amplifier output to DSP 308A to operate the acoustic device in ANR mode, clipping is fully avoided. However, when the switch selectively couples the amplifier output to DSP 308B to operate the acoustic device in communication mode, DSP 308B can apply additional gain (e.g., digital gain) to further increase the SNR for communication operation.

[0037] As demonstrated in the above examples, the operation of switch 306 and / or the adjustment of the gain G applied by amplifier 304 can correspond to the determination of the operating mode of the acoustic device or the connected device. In some cases, determining the operating mode of the acoustic device can be based on one or more direct inputs from the user. In some cases, the operating mode of the acoustic device can be automatically determined based on time, the location of the acoustic device, one or more characteristics of the amplifier output, the analysis of the acoustic signal received from the microphone, etc. For example, if the connected device is running a video conferencing application or making a phone call, the acoustic device can automatically operate in communication mode. In another example, if the acoustic device receives location data indicating that the user is on a bus, the acoustic device can automatically operate in ANR mode. In yet another example, if the analysis of the acoustic signal received from the multi-purpose microphone 302 indicates the presence of both human speech and noisy engine noise, the acoustic device can automatically operate in the "talk-through" mode, thereby eliminating the engine noise while transmitting the human speech to the user.

[0038] The described method for processing the signal received from the multi-purpose microphone can provide the following advantages. By using a single microphone in the implementation of multiple features of the acoustic device, the number of components is reduced while maintaining the optimal gain level for each feature of the device. This can reduce the cost and size of the acoustic device. It can also allow for the inclusion of additional microphones on the acoustic device that can improve performance (e.g., feedforward ANR performance). The method described herein can also improve the stability of the ANR device.

[0039] Figure 4An exemplary signal processing system 400 is shown that is configured to process signals received from a multi-purpose microphone to implement ANR features and communication features. As in signal processing system 300, signal processing system 400 includes a multi-purpose microphone 402 coupled to an amplifier 404. The amplifier 404 may apply a gain G2 to the signal generated by the multi-purpose microphone 402. For example, the gain applied by the amplifier 404 may be an analog gain, and the amplifier 404 may be a variable gain amplifier (VGA). The output of the amplifier 404 is coupled to a switch 406 that is configured to selectively couple the amplifier output to one or more digital signal processors (DSPs) depending on the operating mode of the acoustic device or the connected device. Specifically, the switch 406 is configured to selectively couple the amplifier output to a feedforward compensator 408C to implement the ANR feature of the device, or selectively couple the amplifier output to a communication DSP 410 to implement the communication feature of the device. As shown, signal processing system 400 is currently configured to operate in the ANR mode of the device.

[0040] In signal processing system 400, the signals received from the multi-purpose microphone 402 are combined with signals from additional microphones and the device to implement the ANR feature and the communication feature of the acoustic device. Although Figure 4 is a specific implementation of signal processing system 400, in some cases, one or more other multi-purpose microphones or dedicated microphones or both may be included to implement the features of the acoustic device.

[0041] To implement the ANR feature, in addition to the signal from the multi-purpose microphone 402, system 400 also includes signals from a dedicated feedback microphone 414 and a dedicated feedforward microphone 416. Signal processing system 400 may also include an audio signal 412 (e.g., an audio playback signal from a phone) from the acoustic device or the connected device that is intended to be presented to the user. The audio signal is processed by an equalization compensator K eq 408A, the signal from the feedback microphone 414 is processed by a feedback compensator K fb 408B, and the signal from the feedforward microphone 416 is processed by a feedforward compensator K ff 408C. In some cases, the feedforward compensator K ff 408C may also include a parallel through filter to allow for through hearing, as described in U.S. Patent No. 10,096,313, which is incorporated herein by reference in its entirety. The outputs of the compensators (collectively 408) are then combined to generate an anti-noise signal that is passed to be output by a transducer 424.

[0042] In some cases, one or more of the audio signals in audio signal 412, the signal from feedback microphone 414, and the signal from feedforward microphone 416 may be amplified before being processed by compensator 408. For example, amplifier 420 may apply a gain G1 to the signal from feedforward microphone 416 before the feedforward compensator 408C processes it.

[0043] In some cases, one or more of the audio signals in audio signal 412, the signal from feedback microphone 414, and the signal from feedforward microphone 416 may be converted to digital signals before being processed by compensator 408. For example, signal processing system 400 may include one or more ADCs disposed before compensator 408. Additionally, in some cases, a digital-to-analog converter (DAC) may be included before transducer 424 to convert the digital output of compensator 408 to an analog signal.

[0044] In some cases, compensator 408 may be implemented using a separate DSP or may be implemented on a single DSP. In some cases, one or more DSPs implementing compensator 408 may be included on a single processing chip 428, which may further include an ADC and / or a DAC.

[0045] In the case where the amplified output of the multi-purpose microphone 402 is selectively coupled to the feedforward compensator 408C (e.g., in the ANR operating mode of the acoustic device), the multi-purpose microphone can effectively act as an additional feedforward microphone. In such cases, the amplified output of the multi-purpose microphone 402 may be combined (e.g., summed) with the amplified output of the feedforward microphone 416 before being processed by the feedforward compensator 408C to generate an anti-noise signal. Using the multi-purpose microphone 402 as an additional feedforward microphone can have the benefit of reducing the total gain required in the feedforward signal path, thereby providing more headroom and reducing the chance of instability in the ANR system. As used herein, the term headroom includes the difference between the signal processing capabilities of electrical components (such as compensator 408 and transducer 424) and the maximum level of the signal in the signal path (such as the feedforward signal path or the feedback signal path). The reduced signal path gain can also allow the ANR system to better tolerate non-ideal microphone positions, such as microphone positions closer to the periphery of the earcup of the acoustic device, where the coupling between the microphone and the transducer may be high.

[0046] To implement communication features, in addition to the signal from the multi-purpose microphone 402, the system 400 also includes a signal from a dedicated communication microphone 418. The communication microphone 418 is coupled to an amplifier 422. The amplifier 422 can apply a gain G3 to the signal generated by the communication microphone 418. Then, the amplified output is transmitted for processing by the communication DSP 410 that outputs the voice signal 426. In some cases, the voice signal 426 is sent to the processing chip 428 and added to the output from the compensator 408 for output at the transducer 424 (e.g., a speaker). In some cases, the voice signal 426 can be sent to one or more other devices for further processing or for output by one or more other transducers.

[0047] In some cases, the signal from the communication microphone 418 can be converted to a digital signal before being processed by the communication DSP 410. For example, the signal processing system 400 can include one or more ADCs disposed before the communication DSP 410. Additionally, in some cases, a digital-to-analog converter (DAC) can be included after the communication DSP 410 to convert the digital output of the communication DSP 410 into the analog voice signal 426. In some cases, the communication DSP 410, ADC, and / or DAC can be included on the processing chip 430.

[0048] In the case where the amplified output of the multi-purpose microphone 402 is selectively coupled to the communication DSP 410 (e.g., in the communication operation mode of the acoustic device), the multi-purpose microphone can effectively act as an additional communication microphone. In such cases, the amplified output of the multi-purpose microphone 402 can be passed to the communication DSP 410 for joint processing with the signal from the dedicated communication microphone 418. For example, a beamforming process can be implemented by the communication DSP 410 to optimize the pickup of the user's voice. Beamforming is described in further detail below with reference to Figure 5 Beamforming is described in further detail.

[0049] In some cases, the gains G1, G2, and G3 applied by the amplifiers 420, 404, and 420, respectively, can be different from each other. In some cases, they can be the same. In some cases, the gains G1, G2, and G3 can be fixed, and in some cases, one or more of the gains G1, G2, and G3 can be variable (e.g., adjusted using a variable gain amplifier).

[0050] In one example, the signal processing system 400 applies a similar gain to the signals from each of the feedforward microphone 416, the multi-purpose microphone 402, and the communication microphone 418 (e.g., such that G1≈G2≈G3). In this example, the similar gain applied by each of the amplifiers 420, 404, and 422 can be an analog gain that is low enough to be suitable for implementing the ANR feature of the acoustic device (e.g., increasing the SNR while preventing frequent clipping). For example, in normal use cases, the applied gain can be set to the highest value tolerable by the ANR system without significant clipping occurring too frequently in the acoustic device. Thus, in the case where the amplified output of the multi-purpose microphone 402 is coupled to the feedforward compensator 408C (e.g., in the ANR mode of the acoustic device), objectionable clipping of the acoustic signal is substantially avoided. However, in the case where the amplified output of the multi-purpose microphone 402 is coupled to the communication DSP 410 (e.g., in the communication mode of the acoustic device), the communication DSP 410 can be configured to provide additional amplification (e.g., by applying digital gain) to further increase the SNR in cases where clipping is not objectionable.

[0051] In another example, the signal processing system 400 can apply different gains using the amplifiers 420, 404, and 422. In particular, the amplifier 422 coupled to the communication microphone 418 can apply a higher gain G3 than the gain G1 applied by the amplifier 420. This may be because clipping of the acoustic signal from the feedforward microphone 416 is more objectionable than clipping of the acoustic signal from the communication microphone 418. In this example, the amplifier 404 can be a variable gain amplifier that adjusts the level of the applied gain G2 according to the operating mode of the acoustic device. For example, when the acoustic device is operating in the ANR mode such that the multi-purpose microphone 402 acts as an additional feedforward microphone, the gain G2 can be set to a low enough value to prevent frequent clipping. However, when the acoustic device is operating in the communication mode such that the multi-purpose microphone 402 acts as an additional communication microphone, the gain G2 can be increased to a higher value to further increase the SNR.

[0052] Although Figure 3 and 4 depicts a particular exemplary arrangement of components for implementing the techniques described herein, other components and / or arrangements of components can be used without departing from the scope of the present disclosure. In some specific implementations, the arrangement of components along the feedforward path can sequentially include an analog microphone, an amplifier (e.g., VGA), an analog-to-digital converter (ADC), a digital adder, a feedforward compensator, and another digital adder. This is similar to Figure 4The order depicted in the feed-forward path. In some specific implementations, the arrangement of components along the feed-forward path may include an analog microphone, an analog adder (in the case of multiple microphones), an ADC, an amplifier (e.g., a VGA), and a feed-forward compensator.

[0053] As previously mentioned, in some cases, the signal processing systems 300, 400 may use beamforming to enhance the component of the audio signal relative to background noise. For example, the beamforming process may be implemented on the communication DSP 410 to generate a voice signal 426 that includes an enhanced user voice component relative to background noise and other speakers. Figure 5 Is a block diagram of an exemplary signal processing system 500 that implements the beamforming process. A set of multiple microphones 502 converts acoustic energy into an electrical signal 504 and provides the signal 504 to each of two array processors 506, 508. For example, the set of microphones 502 may correspond to the multi-purpose microphone 402 and the dedicated communication microphone 418. The signal 504 may be in analog form. Alternatively, one or more analog-to-digital converters (ADCs) (not shown) may first convert the microphone output so that the signal 504 can be in digital form.

[0054] The array processors 506, 508 apply array processing techniques (such as phased arrays, delay-and-sum techniques, etc.) and may utilize minimum variance distortionless response (MVDR) and linearly constrained minimum variance (LCMV) techniques to adjust the responsiveness of the set of microphones 502 to enhance or reject acoustic signals from various directions. Beamforming enhances acoustic signals from a specific direction or range of directions, while null steering reduces or rejects acoustic signals from a specific direction or range of directions.

[0055] The first array processor 506 is a beamformer that is used to maximize the acoustic response of the set of microphones 502 in the direction of the user's mouth (e.g., pointing in front of and slightly below the earcup) and provide a main signal 510. Due to the beamforming array processor 506, the main signal 510 includes higher signal energy due to user speech than any individual microphone signal 504.

[0056] The second array processor 508 steers a null towards the user's mouth and provides a reference signal 512. Since the null points towards the user's mouth, the reference signal 512 includes minimal (if any) signal energy due to user speech. Thus, the reference signal 512 consists essentially of components due to background noise and acoustic sources not due to user speech, i.e., the reference signal 512 is a signal related to the acoustic environment without user speech.

[0057] In some examples, the array processor 506 is a super-directional near-field beamformer that enhances the acoustic response in the direction of the user's mouth, and the array processor 508 is a delay-and-sum algorithm that steers a null (i.e., reduces the acoustic response) in the direction of the user's mouth.

[0058] The primary signal 510 includes a user voice component and includes a noise component (e.g., background, other speakers, etc.), while the reference signal 512 includes substantially only a noise component. If the reference signal 512 is nearly the same as the noise component of the primary signal 510, the noise component of the primary signal 510 can be removed by simply subtracting the reference signal 512 from the primary signal 510. However, in practice, the noise components of the primary signal 510 and the reference signal 512 are not the same. Instead, the reference signal 512 can be correlated with the noise component of the primary signal 510, and in such cases, adaptive filtering can be used to remove at least some of the noise component from the primary signal 510 by using the reference signal 512 that is correlated with the noise component.

[0059] The primary signal 510 and the reference signal 512 are provided to and received by an adaptive filter 514, which attempts to remove components from the primary signal 510 that are not related to the user's voice. Specifically, the adaptive filter 514 attempts to remove components that are related to the reference signal 512. The adaptive filter can be designed to remove components related to the reference signal. For example, some examples include a normalized least mean square (NLMS) adaptive filter or a recursive least squares (RLS) adaptive filter. The output of the adaptive filter 514 is a voice estimate signal 516, which represents an approximation of the user voice signal.

[0060] Exemplary adaptive filters 514 can include various types that incorporate various adaptive techniques (e.g., NLMS, RLS, etc.). Adaptive filters generally include a digital filter that receives a reference signal related to the unwanted components of the primary signal. The digital filter attempts to generate an estimate of the unwanted components in the primary signal from the reference signal. By definition, the unwanted components of the primary signal are the noise components. The estimate of the noise components by the digital filter is the noise estimate. If the digital filter produces a good noise estimate, the noise component can be effectively removed from the primary signal by simply subtracting the noise estimate. On the other hand, if the digital filter does not generate a good estimate of the noise component, this subtraction may be ineffective or may degrade the primary signal, e.g., increase the noise. Therefore, the adaptive algorithm operates in parallel with the digital filter and adjusts the digital filter in the form of, for example, changing weights or filter coefficients. In some examples, the adaptive algorithm can monitor the primary signal when it is known to have only noise components (i.e., when the user is not speaking) and adjust the digital filter to generate a noise estimate that matches the primary signal, which at this time includes only noise components.

[0061] The adaptive algorithm can know when the user is not speaking by various means. In at least one example, the system enforces a pause or mute period after triggering voice enhancement. For example, the user may need to press a button or say a wake-up command and then pause until the system indicates to the user that it is ready. During the required pause, the adaptive algorithm monitors the main signal that does not include any user speech and adapts the filter to the background noise. Then, when the user speaks, the digital filter generates a good noise estimate and subtracts it from the main signal to generate a speech estimate, for example, the speech estimate signal 516.

[0062] In some examples, the adaptive algorithm can update the digital filter substantially continuously and can freeze the filter coefficients when it detects that the user is speaking, such as pausing the adjustment. Alternatively, the adaptive algorithm can be disabled until voice enhancement is needed and then update the filter coefficients only when it detects that the user is not speaking. Some examples of systems for detecting whether the user is speaking are described in the co-pending U.S. Patent Application No. 15 / 463,259, titled "SYSTEMS AND METHODS OF DETECTING SPEECH ACTIVITY OF HEADPHONE USER", filed on March 20, 2017, which is hereby incorporated by reference in its entirety.

[0063] In certain examples, the weights and / or coefficients applied by the adaptive filter can be established or updated by a parallel or background process. For example, an additional adaptive filter can operate in parallel with the adaptive filter 514 and continuously update its coefficients in the background, that is, without affecting Figure 5 the active signal processing shown in the exemplary system 500 until the additional adaptive filter provides a better speech estimate signal. The additional adaptive filter can be referred to as a background or parallel adaptive filter, and when the parallel adaptive filter provides a better speech estimate, the weights and / or coefficients used in the parallel adaptive filter can be copied to the active adaptive filter, such as the adaptive filter 514.

[0064] In certain examples, a reference signal such as the reference signal 512 can be derived by other methods or by other components other than those discussed above. For example, the reference signal can be derived from one or more individual microphones (such as rear microphones) that are less responsive to the user's speech. Alternatively, beamforming techniques can be used to direct a wide beam away from the user's mouth to derive the reference signal from the set of microphones 502, or the reference signals can be combined without an array or beamforming techniques in response to the acoustic environment, generally without considering the user speech components included therein.

[0065] Exemplary system 500 can be advantageously applied to an acoustic device (e.g., headset 100) to pick up a user's voice in a manner that enhances the user's voice and reduces background noise. For example, signals from the multi-purpose microphone 402 and the dedicated communication microphone 418( Figure 4 ) can be processed by the exemplary system 500 to provide a voice estimation signal 516 having a voice component that is enhanced relative to background noise, the voice component representing the voice from the user (i.e., the wearer of the headset 100). As described above, in some examples, the array processor 506 is a super-directional near-field beamformer that enhances the acoustic response in the direction of the user's mouth, and the array processor 508 is a delay-and-sum algorithm that steers a null (i.e., reduces the acoustic response) in the direction of the user's mouth. Exemplary system 500 illustrates a system and method for monaural voice enhancement from a set of microphones 502. In some cases, variations of system 500 include at least binaural processing of two arrays of microphones (e.g., a right array and a left array), further voice enhancement through spectral processing, and separate processing of the signal through sub-bands.

[0066] Figure 6 FIG. 600 is a flowchart of an exemplary process 600 for processing a signal received from a multi-purpose microphone. At least a portion of process 600 can be implemented using one or more processing devices (e.g., one or more DSPs 308 described with reference to Figure 3 and / or processing chips 428, 430 described with reference to Figure 4 ). Operations of process 600 include receiving an input signal (602) representing audio captured by a sensor disposed in an ANR device. In some specific implementations, the ANR device can correspond to the headset 100 described with reference to Figure 1 and Figure 2 . In some specific implementations, the sensor disposed in the ANR device can correspond to a microphone disposed in the headset 100, such as the front microphone 202 and / or the rear microphone 206. In some specific implementations, the sensor can also correspond to a dedicated feedback microphone (e.g., feedback microphone 414), a dedicated feedforward microphone (e.g., feedforward microphone 416), a dedicated communication microphone (e.g., communication microphone 418), and / or a multi-purpose microphone (e.g., multi-purpose microphones 302, 402).

[0067] The operations of process 600 also include determining that the ANR device is operating in a first operating mode (604). For example, the first operating mode may include a voice communication mode (also referred to as a communication mode), such as a mode in which the ANR device is used for a telephone call. The operations of process 600 also include applying a first gain to the input signal to generate a first amplified input signal in response to determining that the ANR device is operating in the first operating mode (606). In some particular implementations, the first gain may be applied by one or more amplifiers (such as amplifiers 304, 420, 404, and 422 described with reference to Figure 3 and Figure 4 . In some particular implementations, the first gain may be applied at least in part by a DSP (such as DSP 308 and / or communication DSP 410). In some particular implementations, in response to determining that the ANR device is operating in the first operating mode, one or more other attributes of the input signal may be applied or adjusted in addition to the first gain.

[0068] The operations of process 600 also include determining that the ANR device is operating in a second operating mode different from the first operating mode (608). For example, the second operating mode may include a noise reduction mode, such as a mode in which the ANR device is used to reduce the impact of ambient noise. The operations of process 600 also include applying a second gain to the input signal to generate a second amplified input signal in response to determining that the ANR device is operating in the second operating mode (610). In some particular implementations, the second gain may be applied by one or more amplifiers (such as amplifiers 304, 420, 404, and 422 described with reference to Figure 3 and Figure 4 . In some particular implementations, the second gain may be applied at least in part by a DSP (such as DSP 308 and / or communication DSP 410). In some particular implementations, in response to determining that the ANR device is operating in the second operating mode, one or more other attributes of the input signal may be applied or adjusted in addition to the second gain. In some particular implementations, the gain applied to the input signal in the noise reduction mode of the ANR device is lower than in the voice communication mode of the ANR device.

[0069] The operation of process 600 further includes processing the first amplified input signal or the second amplified input signal to generate an output signal (612). In some embodiments, processing the first amplified input signal or the second amplified input signal may include receiving a second input signal representing audio captured by a second sensor disposed in the ANR device, combining the amplified input signal and the second input signal to produce a combined input signal, and processing the combined input signal using at least one compensator to generate an output signal for the ANR device. For example, the amplified input signal may correspond to an amplified signal generated by the multi-purpose microphone 402, and the second input signal may correspond to the dedicated feedforward microphone 416. In some embodiments, processing the first amplified input signal or the second amplified input signal may include processing the corresponding amplified input signal with one or more ANR compensators (e.g., compensator 408). In some embodiments, processing the first amplified input signal or the second amplified input signal may include processing the device with the communication DSP 410. In some embodiments, processing the first amplified input signal or the second amplified input signal may include performing a beamforming process. In some embodiments, the beamforming process may include: receiving a second input signal representing audio captured by a second sensor disposed in the ANR device; processing the first amplified input signal or the second amplified input signal and the second input signal to direct a beam toward the mouth of the user of the ANR device to generate a primary signal; processing the corresponding amplified input signal and the second input signal to direct a null toward the mouth of the user of the ANR device to generate a reference signal; and using the reference signal as a noise reference to process the primary signal to generate an output signal for the ANR device. For example, in this case, the amplified input signal may correspond to an amplified signal generated by the multi-purpose microphone 402, and the second input signal may correspond to a signal generated by the dedicated communication microphone 418. In some embodiments, the output signal for the ANR device may be an anti-noise signal, a voice signal approximating the voice of the user of the ANR device, and / or a combination of both. In some embodiments, the output signal includes a drive signal for a transducer (e.g., transducer 424) of the ANR device.

[0070] Figure 7 is a block diagram of an exemplary computer system 700 that may be used to perform the operations described above. For example, at least a portion of the computer system 700 may be used to implement as described above with reference to Figure 1 , Figure 3 , Figure 4 and Figure 5Any of the systems 100, 300, 400, and 500 described. System 700 includes a processor 710, a memory 720, a storage device 730, and an input / output device 740. Each of the components 710, 720, 730, and 740 can be interconnected, for example, using a system bus 750. The processor 710 is capable of processing instructions for execution within the system 700. In one specific implementation, the processor 710 is a single-threaded processor. In another specific implementation, the processor 710 is a multi-threaded processor. The processor 710 is capable of processing instructions stored in the memory 720 or on the storage device 730.

[0071] The memory 720 stores information within the system 700. In one specific implementation, the memory 720 is a computer-readable medium. In one specific implementation, the memory 720 is a volatile memory unit. In another specific implementation, the memory 720 is a non-volatile memory unit.

[0072] The storage device 730 is capable of providing mass storage for the system 700. In one specific implementation, the storage device 730 is a computer-readable medium. In various different specific implementations, the storage device 730 can include, for example, a hard disk device, an optical disk device, a storage device shared by multiple computing devices over a network (e.g., a cloud storage device), or some other large-capacity storage device.

[0073] The input / output device 740 provides input / output operations for the system 700. In one specific implementation, the input / output device 740 can include one or more network interface devices (e.g., an Ethernet card), serial communication devices (e.g., and an RS-232 port), and / or wireless interface devices (e.g., and an 802.11 card). In another specific implementation, the input / output device can include driver devices that are configured to receive input data and send output data to other input / output devices, such as a keyboard, a printer, and a display device 760, as well as an acoustic transducer / speaker 770.

[0074] Although an exemplary processing system has been described in Figure 7 , the specific implementations of the subject matter and functional operations described in this specification can be implemented in other types of digital electronic circuits, or in computer software, firmware, or hardware (including the structures disclosed in this specification and their structural equivalents, or in a combination of one or more of them).

[0075] This specification uses the term "configured" in connection with systems and computer program components. For a system of one or more computers, being configured to perform particular operations or actions means that software, firmware, hardware, or a combination thereof has been installed on the system that in operation causes the system to perform those operations or actions. For one or more computer programs, "configured to" perform particular operations or actions means that the one or more programs include instructions that, when executed by a data processing apparatus, cause the apparatus to perform the operations or actions.

[0076] Embodiments of the subject matter and the functional operations described in this specification can be implemented in digital electronic circuitry, in tangibly embodied computer software or firmware, in computer hardware (including the structures disclosed in this specification and their structural equivalents), or in a combination of one or more of them. The specific implementations of the subject matter described in this specification can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions encoded on a tangible non-transitory storage medium for execution by, or to control the operation of, a data processing apparatus. The computer storage medium can be a machine-readable storage device, a machine-readable storage substrate, a random or serial access memory device, or a combination of one or more of them. Alternatively or in addition, the program instructions can be encoded on an artificially generated propagated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to a suitable receiver apparatus for execution by the data processing apparatus.

[0077] The term "data processing apparatus" refers to data processing hardware and encompasses all types of apparatus, devices, and machines for processing data, including, by way of example, a programmable processor, a computer, or multiple processors or computers. The apparatus can also be or further include special purpose logic circuitry, such as an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit). In addition to hardware, the apparatus can optionally include code that creates an execution environment for the computer program, such as code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.

[0078] A computer program may also be termed or described as a program, software, software application, app, module, software module, script, or code, and can be written in any form of programming language, including compiled or interpreted languages, or declarative or procedural languages, and the computer program can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A program may but need not correspond to a file in a file system. A program may be stored in a part of a file that holds other programs or data, such as one or more scripts stored in a markup language document, in a single file dedicated to the program being considered, or in multiple coordinated files, such as files that hold parts of one or more modules, subroutines, or code. A computer program may be deployed on one computer or executed on multiple computers distributed at one site or multiple sites and interconnected by a data communication network.

[0079] The processes and logical flows described in this specification can be performed by one or more programmable computers executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logical flows can also be performed by, or by a combination of, special purpose logic circuitry, such as an FPGA or ASIC, or special purpose logic circuitry and one or more programmed computers.

[0080] For providing interaction with a user, embodiments of the subject matter described in this specification can be implemented on a computer having a display device (e.g., a light emitting diode (LED) or liquid crystal display (LCD) monitor) for displaying information to the user and a keyboard and a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the computer. Other kinds of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback, such as visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic input, speech input, or tactile input. Additionally, a computer can interact with a user by sending documents to and receiving documents from the device used by the user; for example, by sending a web page to a web browser on a user device in response to a request received from the web browser. Further, a computer can interact with a user by sending text messages or other forms of messages to a personal device (e.g., a smartphone running a messaging application) and receiving a returned response message from the user.

[0081] Embodiments of the subject matter described in this specification can be implemented in a computing system that includes a back-end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front-end component (e.g., a client computer having a graphical user interface, a web browser, or an app through which a user can interact with a particular implementation of the subject matter described in this specification), or any combination of one or more of such back-end, middleware, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include a local area network (LAN) and a wide area network (WAN) (e.g., the Internet).

[0082] The computing system can include a client and a server. The client and the server are typically remote from each other and typically interact through a communication network. The relationship of the client and the server is generated by computer programs that run on the respective computers and that have a client-server relationship to each other. In some embodiments, the server transmits data (e.g., an HTML page) to a user device, e.g., to display data to and receive user input from a user interacting with the device acting as the client. Data generated at the user device (e.g., the results of a user interaction) can be received at the server from the device.

[0083] Other embodiments and applications not specifically described herein are also within the scope of the following claims. Elements of the different embodiments described herein can be combined to form other embodiments not specifically recited above. Some elements can be removed from the structures described herein without adversely affecting their operation. Additionally, various separate elements can be combined into one or more separate elements to perform the functions described herein.

Claims

1. A method, the method comprising: Receiving an input signal representing audio captured by a sensor disposed in an active noise reduction (ANR) device; Determining, by one or more processing devices, that the ANR device is operating in a first operation mode; In response to determining that the ANR device is operating in the first operation mode, applying a first gain to the input signal to generate a first amplified input signal, and providing the first amplified input signal to a first processor corresponding to the first operation mode; Determining, by the one or more processing devices, that the ANR device is operating in a second operation mode different from the first operation mode; In response to determining that the ANR device is operating in the second operation mode, applying a second gain to the input signal to generate a second amplified input signal, and providing the second amplified input signal to a second processor corresponding to the second operation mode, the second processor being different from the first processor, wherein the second gain is different from the first gain; Processing the first amplified input signal or the second amplified input signal to generate an output signal; And Generating an audio output based on the output signal by a sound transducer.

2. The method according to claim 1, wherein the first operation mode of the ANR device includes a voice communication mode.

3. The method according to claim 1, wherein the second operation mode of the ANR device includes a noise reduction mode.

4. The method according to claim 1, wherein the sensor includes a microphone of the ANR device.

5. The method according to claim 1, wherein the output signal includes a drive signal for the sound transducer.

6. The method according to claim 5, comprising: Processing the first amplified input signal or the second amplified input signal using at least one compensator to generate the drive signal for the sound transducer, the drive signal including an anti-noise signal.

7. The method according to claim 1, comprising: Receiving a second input signal representing audio captured by a second sensor disposed in the ANR device; Combining the first amplified input signal or the second amplified input signal and the second input signal to produce a combined input signal; And Processing the combined input signal using at least one compensator to generate the output signal for the ANR device, the output signal including an anti-noise signal.

8. The method according to claim 1, comprising: Receiving a second input signal representing audio captured by a second sensor disposed in the ANR device; Processing the first amplified input signal or the second amplified input signal and the second input signal to direct a beam towards the mouth of a user of the ANR device, thereby generating a main signal; Processing the corresponding amplified input signal and the second input signal to direct a null towards the mouth of the user of the ANR device, thereby generating a reference signal; And Processing the main signal using the reference signal as a noise reference to generate the output signal for the ANR device.

9. The method according to claim 8, wherein one of the following is used to steer the beam or null: near-field beamforming technique or delay-and-sum beamforming technique.

10. An automatic noise reduction (ANR) device, the ANR device comprising: one or more sensors configured to capture audio; at least one amplifier configured to amplify an input signal representative of the audio captured by the one or more sensors; a controller comprising one or more processing devices, wherein the controller is configured to: determine that the ANR device is operating in a first operating mode, in response to determining that the ANR device is operating in the first operating mode, apply a first gain to the input signal to generate a first amplified input signal, and provide the first amplified input signal to a first processor corresponding to the first operating mode, determine that the ANR device is operating in a second operating mode different from the first operating mode, in response to determining that the ANR device is operating in the second operating mode, apply a second gain to the input signal to generate a second amplified input signal, and provide the second amplified input signal to a second processor corresponding to the second operating mode, the second processor being different from the first processor, wherein the second gain is different from the first gain, and process the first amplified input signal or the second amplified input signal to generate an output signal; and a sound transducer configured to generate an audio output based on the output signal.

11. The device according to claim 10, wherein the first operating mode of the ANR device comprises a voice communication mode.

12. The device according to claim 10, wherein the second operating mode of the ANR device comprises a noise reduction mode.

13. The device according to claim 10, wherein the sensor comprises a microphone of the ANR device.

14. The device according to claim 10, wherein the output signal comprises a drive signal for the sound transducer.

15. The device according to claim 14, wherein the controller comprises at least one compensator configured to process the first amplified input signal or the second amplified input signal to generate the drive signal for the sound transducer, the drive signal comprising an anti-noise signal.

16. The device according to claim 10, wherein the controller is configured to: receive a second input signal representative of audio captured by a second sensor disposed in the ANR device; combine the first amplified input signal or the second amplified input signal and the second input signal to produce a combined input signal; and process the combined input signal using at least one compensator to generate the output signal for the ANR device, the output signal comprising an anti-noise signal.

17. The device according to claim 10, wherein the controller is configured to: receive a second input signal representative of audio captured by a second sensor disposed in the ANR device; Process the first amplified input signal or the second amplified input signal and the second input signal to direct a beam towards the user's mouth of the ANR device, thereby generating a primary signal; Process the corresponding amplified input signal and the second input signal to direct a null towards the user's mouth of the ANR device, thereby generating a reference signal; And Use the reference signal as a noise reference to process the primary signal to generate an output signal for the ANR device.

18. The apparatus according to claim 17, wherein one of the following is used to direct the beam or the null: near-field beamforming technique or delay-and-sum beamforming technique.

19. One or more non-transitory machine-readable storage devices storing machine-readable instructions that cause one or more processing devices to perform operations, the operations including: Receiving an input signal representing audio captured by a sensor disposed in an active noise reduction (ANR) device; Determining that the ANR device is operating in a first operating mode; In response to determining that the ANR device is operating in the first operating mode, applying a first gain to the input signal to generate a first amplified input signal and providing the first amplified input signal to a first processor corresponding to the first operating mode; Determining that the ANR device is operating in a second operating mode different from the first operating mode; In response to determining that the ANR device is operating in the second operating mode, applying a second gain to the input signal to generate a second amplified input signal and providing the second amplified input signal to a second processor corresponding to the second operating mode, the second processor being different from the first processor, wherein the second gain is different from the first gain; Processing the first amplified input signal or the second amplified input signal to generate an output signal; and Causing a sound transducer to generate an audio output based on the output signal.

20. The one or more non-transitory machine-readable storage devices according to claim 19, wherein The first operating mode of the ANR device includes a voice communication mode, and wherein the second operating mode of the ANR device includes a noise reduction mode.

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