Abstract: Various aspects include a wearable audio device having active noise reduction (ANR). In some cases, a method for processing audio signals includes receiving a noise reduction signal configured to modify an audio signal and generate a noise reduced audio signal, the noise reduction signal having a nominal loop gain; and generating an adjusted noise reduction signal in response to a detected adverse low frequency event, the adjusted noise reduction signal having a modulated loop gain configured to reduce artifacts in the noise reduced audio signal.

Abstract: An active noise reduction (ANR) device includes an acoustic transducer, a first sensor, and a second sensor. The acoustic transducer is configured to generate output audio. The first sensor is configured to capture audio originating from an external environment of the ANR device. The second sensor is configured to generate a signal indicative of (1) the audio originating from the external environment and (2) the output audio generated by the acoustic transducer. The output audio generated by the acoustic transducer is modified based on a portion of the signal generated by the second sensor, the portion being attributable to a resonant mode of a user's ear canal.

Abstract: A playback audio signal is combined with a feedback signal from a feedback microphone to provide a first combined signal. The first combined signal is filtered with a feedback filter to provide a driver command signal. The driver command signal is provided to an acoustic transducer for transduction to acoustic energy. The first combined signal is compared with the feedback signal to detect a feedback instability based upon the comparison.

Abstract: Various aspects include a wearable audio device having active noise reduction (ANR). In some cases, an ANR system for a wearable audio device includes: a fixed filter that receives a signal from a feedback microphone and outputs a noise reduction signal, where the fixed filter is configured to provide ANR with a nominal loop gain; and a tunable filter that outputs an adjusted noise reduction signal by modulating the nominal loop gain in response to low frequency noise being detected in the noise reduction signal, where modulating the nominal loop gain includes reducing low frequency ANR performance.

Abstract: Various aspects include a wearable audio device having active noise reduction (ANR). In some cases, an ANR system for a wearable audio device includes: a fixed filter that receives a signal from a feedback microphone and outputs a noise reduction signal, where the fixed filter is configured to provide ANR with a nominal loop gain; and a tunable filter that outputs an adjusted noise reduction signal by modulating the nominal loop gain in response to low frequency noise being detected in the noise reduction signal, where modulating the nominal loop gain includes reducing low frequency ANR performance.

Abstract: Various aspects include a wearable audio device having active noise reduction (ANR), where the ANR device includes: a feedback microphone; an electroacoustic transducer; and a feedback compensator configured to output a noise reduction signal to the electroacoustic transducer in response to a feedback signal from the feedback microphone, wherein the feedback compensator includes a tunable filter that modulates a loop gain in response to an adverse low frequency event being detected in the noise reduction signal outputted from the tunable filter, wherein the tunable filter is configured to maintain a substantially similar loop gain shape near a low frequency cross-over as the low frequency cross-over changes during loop gain modulation.

Abstract: Various aspects include a wearable audio device having active noise reduction (ANR), where the ANR device includes: a feedback microphone; an electroacoustic transducer; and a feedback compensator configured to output a noise reduction signal to the electroacoustic transducer in response to a feedback signal from the feedback microphone, wherein the feedback compensator includes a tunable filter that modulates a loop gain in response to an adverse low frequency event being detected in the noise reduction signal outputted from the tunable filter, wherein the tunable filter is configured to maintain a substantially similar loop gain shape near a low frequency cross-over as the low frequency cross-over changes during loop gain modulation.

Abstract: Various aspects include a wearable audio device having active noise reduction (ANR), where the ANR device includes: a feedback microphone; an electroacoustic transducer; and a feedback compensator configured to output a noise reduction signal to the electroacoustic transducer in response to a feedback signal from the feedback microphone, wherein the feedback compensator includes a tunable filter that modulates a loop gain in response to an adverse low frequency event being detected in the noise reduction signal outputted from the tunable filter, wherein the tunable filter is configured to maintain a substantially similar loop gain shape near a low frequency cross-over as the low frequency cross-over changes during loop gain modulation.

Abstract: Various aspects include a wearable audio device having active noise reduction (ANR), where the ANR device includes: a feedback microphone; an electroacoustic transducer; and a feedback compensator configured to output a noise reduction signal to the electroacoustic transducer in response to a feedback signal from the feedback microphone, wherein the feedback compensator includes a tunable filter that modulates a loop gain in response to an adverse low frequency event being detected in the noise reduction signal outputted from the tunable filter, wherein the tunable filter is configured to maintain a substantially similar loop gain shape near a low frequency cross-over as the low frequency cross-over changes during loop gain modulation.

Abstract: The technology described herein can be embodied in a method for estimating a power spectral density of noise, the method including receiving an input signal representing audio captured using a microphone. The input signal includes a first portion that represents acoustic outputs from two or more audio sources, and a second portion that represents a noise component. The method also includes iteratively modifying a frequency domain representation of the input signal, such that the modified frequency domain representation represents a portion of the input signal in which effects due to the first portion are substantially reduced. The method further includes determining, from the modified frequency domain representation, an estimate of a power spectral density of the noise, and generating a control signal configured to adjust one or more gains of an acoustic transducer. The control signal is generated based on the estimate of the power spectral density of the noise.

Abstract: This document describes a method that includes receiving a driver signal for an acoustic transducer of an acoustic device. The method also includes receiving a signal from a microphone of the acoustic device, and, processing the driver signal through a filter to provide a reference signal. The filter has a transfer function associated with a condition of the acoustic device. The method also includes comparing the signal to the reference signal to determine whether the signal has a threshold similarity to the reference signal, and, indicating the condition of the acoustic device in respond to the determined threshold similarity.

Abstract: The technology described herein can be embodied in a method for estimating a power spectral density of noise, the method including receiving an input signal representing audio captured using a microphone. The input signal includes a first portion that represents acoustic outputs from two or more audio sources, and a second portion that represents a noise component. The method also includes iteratively modifying a frequency domain representation of the input signal, such that the modified frequency domain representation represents a portion of the input signal in which effects due to the first portion are substantially reduced. The method further includes determining, from the modified frequency domain representation, an estimate of a power spectral density of the noise, and generating a control signal configured to adjust one or more gains of an acoustic transducer. The control signal is generated based on the estimate of the power spectral density of the noise.

Abstract: In an aspect, in general, a system and method compensate for a misalignment characteristic of one or more acceleration sensors fixed to a sprung mass of a vehicle, each acceleration sensor having a location on the vehicle and a desired orientation relative to the vehicle.

Abstract: The technology described herein can be embodied in a method for estimating a power spectral density of noise, the method including receiving an input signal representing audio captured using a microphone. The input signal includes a first portion that represents acoustic outputs from two or more audio sources, and a second portion that represents a noise component. The method also includes iteratively modifying a frequency domain representation of the input signal, such that the modified frequency domain representation represents a portion of the input signal in which effects due to the first portion are substantially reduced. The method further includes determining, from the modified frequency domain representation, an estimate of a power spectral density of the noise, and generating a control signal configured to adjust one or more gains of an acoustic transducer. The control signal is generated based on the estimate of the power spectral density of the noise.

Abstract: The technology described in this document can be embodied in a method that includes receiving an input signal representing audio captured by one or more sensors of an active noise reduction (ANR) headphone, and generating, based on the input signal, a first signal by a compensator disposed in an ANR signal flow path. The method also includes determining one or more characteristics of the first signal, and selecting, based on the one or more characteristics of the first signal, a plurality of filter coefficients for a digital filter disposed in series with the compensator in the ANR signal flow path. The filter coefficients are selected in accordance with a target frequency response of the digital filter. The method further includes generating, by processing the input signal using the plurality of filter coefficients of the digital filter, a feedback control signal for an electroacoustic transducer of the ANR headphone.

Abstract: The technology described herein can be embodied in a method for estimating a power spectral density of noise, the method including receiving an input signal representing audio captured using a microphone. The input signal includes a first portion that represents acoustic outputs from two or more audio sources, and a second portion that represents a noise component. The method also includes iteratively modifying a frequency domain representation of the input signal, such that the modified frequency domain representation represents a portion of the input signal in which effects due to the first portion are substantially reduced. The method further includes determining, from the modified frequency domain representation, an estimate of a power spectral density of the noise, and generating a control signal configured to adjust one or more gains of an acoustic transducer. The control signal is generated based on the estimate of the power spectral density of the noise.

Abstract: A method and system for a noise cancellation comprises an amplifier in communication with three or more speakers disposed in an area. A system controller produces a driver signal for each of the speakers in response to a signal from at least one microphone detecting sound in the area and communicates the driver signals to the amplifier. The amplifier drives each speaker with the driver signal produced for that speaker. In response to the driver signals, the speakers emit sound having a magnitude and phase that combine to attenuate a noise field in the area.

Abstract: Audio systems and methods are provided that detect instability in active feedback noise reduction circuitry. An acoustic transducer converts a driver signal into an acoustic signal, and a microphone provides a feedback signal. The feedback signal is processed, through a first transfer function, to provide an anti-noise signal. The driver signal is based at least in part upon the anti-noise signal, to reduce acoustic noise in the environment of the acoustic transducer. The driver signal is also filtered by a filter having a second transfer function that is inverse of the first transfer function, to provide a reference signal. The feedback signal is compared to the reference signal to determine a feedback instability, based upon the comparison.

Abstract: A method and system for a noise cancellation comprises an amplifier in communication with the three or more speakers disposed in an area. A system controller produces a driver signal for each of the speakers in response to a signal from at least one microphone detecting sound in the area and communicates the driver signals to the amplifier. The amplifier drives each speaker with the driver signal produced for that speaker. In response to the driver signals, the speakers emit sound that combined produces a substantially uniform sound pressure field for a particular zone within the area. The substantially uniform sound pressure field produced by the speakers has a magnitude and phase adapted to attenuate a noise field in the area corresponding to the sound detected by the at least one microphone.

Abstract: The technology described in this document can be embodied in a method that includes receiving an input signal representing audio captured by one or more sensors of an active noise reduction (ANR) headphone, and generating, based on the input signal, a first signal by a compensator disposed in an ANR signal flow path. The method also includes determining one or more characteristics of the first signal, and selecting, based on the one or more characteristics of the first signal, a plurality of filter coefficients for a digital filter disposed in series with the compensator in the ANR signal flow path. The filter coefficients are selected in accordance with a target frequency response of the digital filter. The method further includes generating, by processing the input signal using the plurality of filter coefficients of the digital filter, a feedback control signal for an electroacoustic transducer of the ANR headphone.