A headphone having a speaker, a feedforward microphone, a feedback microphone, and an OED processor. The speaker is configured to transmit an audio playback signal based on a headphone audio signal. The feedforward microphone is configured to sense an ambient noise signal and transmit a feedforward microphone signal based at least in part on the ambient noise signal. The feedback microphone is configured to sense a total audio signal and transmit a feedback microphone signal based at least in part on the total audio signal, in which the total audio signal is the sum of the audio playback signal and at least a portion of the ambient noise level. The OED processor is configured to determine whether the headphone is off ear or on ear, based at least in part on the headphone audio signal, the feedforward microphone signal, and the feedback microphone signal.

Provided is a technology for generating an elimination filter coefficient for suppressing degradation of noise elimination performance. An elimination filter coefficient generation method for inputting a reference signal output from a reference microphone for collecting noise and an error signal output from an error microphone for collecting sound at a position that needs to be silent, and generating an elimination filter coefficient used for filtering for generating an elimination signal for eliminating noise at the position that needs to be silent from the reference signal includes: a route filtering step for generating a filtered reference signal from the reference signal by filtering using a route filter coefficient indicating acoustic characteristics of a route from a speaker for emitting sound based on the elimination signal to the error microphone; a first noise signal generation step for generating a predetermined signal as a first noise signal; a noise signal addition step for generating an added reference signal from the filtered reference signal and the first noise signal; and an elimination filter coefficient generation step for generating the elimination filter coefficient from the error signal and the added reference signal.

An audio processing system is provided with a speaker, a plurality of microphones, and an audio processing device. The audio processing device includes a plurality of filters that allow audio signals of audio collected by the plurality of microphones to pass any respective first bands included in a band of the audio output from the speaker, a plurality of delayers that delay the audio signals passed through the plurality of filters by delay times corresponding to the first bands respectively, a correlation value calculator that calculates a correlation value of a plurality of audio signals delayed respectively by the plurality of delayers and an audio signal of the audio output from the speaker, and a determinator that determines presence or absence of abnormality in the plurality of microphones and the speaker based on the correlation value.

The present application describes techniques for noise control which utilize a feedback control unit comprising a filter, derived from one or more predetermined filter candidates, for reducing or cancelling a feedback component of a noise control signal.

An active noise control device reduces noise inside a cabin of a car. The active noise control device includes: a controller that decreases a signal level of a canceling signal when a signal level of a received reference signal is lower than a threshold; and a threshold controller that changes the threshold based on at least one of a signal level of an error signal and information on the car.

The technology described in this document can be embodied in a method that includes receiving an input signal representing audio captured by a microphone of an active noise reduction (ANR) headphone, processing, by one or more processing devices, a portion of the input signal to determine a noise level in the input signal, and determining that the noise level satisfies a threshold condition. The method also includes, in response to determining that the noise level satisfies the threshold condition, generating an output signal in which ANR processing on the input signal is controlled in accordance with a target loudness level of the output signal, and driving an acoustic transducer of the ANR headphone using the output signal.

The handling of disturbances to audio signals may be improved with an adaptive noise cancellation (ANC) system that performs frequency-domain adaption. The ANC systems may be configured to determine if a disturbance is present at a first frequency in the second input signal received from the reference microphone. The ANC systems may update an algorithm of an adaptive filter based, at least in part, on the first input signal, the second input signal, and a feedback signal that is based on an output of the adaptive filter by changing parameters of the algorithm such that the adaptive filter adapts around the first frequency differently than other frequencies when the disturbance is present.

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.

An integrated circuit for implementing at least a portion of a personal audio device may include a processing circuit to implement an adaptive filter having a response that generates an anti-noise signal to reduce the presence of the ambient audio sounds at an error microphone, implement a coefficient control block that shapes the response of the adaptive filter in conformity with the error microphone signal by computing coefficients that determine the response of the adaptive filter to minimize the ambient audio sounds at the error microphone, and responsive to detecting a condition that triggers a reset of the adaptive filter, increment the coefficients in a plurality of steps from initial values of the coefficients at a time of triggering the reset to final values of the coefficients at a conclusion of the reset.

The handling of disturbances to audio signals may be improved with an adaptive noise cancellation (ANC) system that performs tone suppression and howl suppression in a collaborative manner. Such ANC systems may be configured to detect a first tone in an input signal at a first tone frequency and extract the detected first tone from the input signal. The ANC systems may also be configured to adaptively filter the extracted first tone to generate a second tone that has a magnitude that is approximately equal to a magnitude of the extracted first tone and a phase that is approximately opposite the phase of the extracted first tone. The ANC systems may be further configured to add the second tone to an intermediate signal that is based, at least in part, on the input signal to generate the output signal.