A active noise cancellation (ANC) system may include an adaptive filter divergence detector for detecting divergence of the one or more controllable filters as they adapt, based on various temporal or frequency domain amplitude characteristics. Upon detection of a controllable filter divergence, the ANC system may be deactivated, or certain speakers may be muted. Alternatively, the ANC system may modify the diverged controllable filters to restore proper operation of the noise cancelling system. This may include adjusting a leakage value of an adaptive filter controller.

An active noise cancellation (ANC) system may include an adaptive filter divergence detector for detecting divergence of the one or more controllable filters as they adapt, based on dynamically adapted thresholds. Upon detection of a controllable filter divergence, the ANC system may be deactivated, or certain speakers may be muted. Alternatively, the ANC system may modify the diverged controllable filters to restore proper operation of the noise cancelling system.

A noise reduction system includes sensors configured to generate an input signal, an adaptive filter configured to represent a transfer function of a path traversed by the input signal, one or more processing devices, and one or more transducers. The processing devices receive the input signal and generate an updated set of filter coefficients of the adaptive filter by separating the input signal into frequency subbands; determining for each subband, coefficients of a corresponding subband adaptive module; and combining the coefficients of multiple subband adaptive modules. Determining the coefficients of the corresponding subband adaptive module includes selecting a subset of a precomputed set of filter coefficients of the adaptive filter. The processing devices process a portion of the input signal using the updated set of filter coefficients of the adaptive filter to generate an output that destructively interferes with another signal traversing the path represented by the transfer function.

A method may include receiving a user trigger signal indicating a user desire to update characteristics of an adaptive filter, receiving an error microphone signal indicative of the output of the transducer and the ambient audio sounds at the transducer, wherein the transducer reproduces both a source audio signal for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer, implementing the adaptive filter having a response that generates the anti-noise signal to reduce the presence of the ambient audio sounds in the error microphone signal, determining an acoustic coupling of the transducer to an error microphone for producing the error microphone signal, and responsive to a change in the acoustic coupling, prompting a user to assert the user trigger signal to indicate user desire to update characteristics of the adaptive filter.

A method of equalising sound in a headset comprising an internal microphone configured to generate a first audio signal, an external microphone configured to generate a second audio signal, a speaker, and one or more processors coupled between the speaker the external microphone, and the internal microphone, the method comprising: while the headset is worn by a user: determining a first audio transfer function between the first audio signal and the second audio signal in the presence of sound at the external microphone; and determining a second audio transfer function between a speaker input signal and the first audio signal with the speaker being driven by the speaker input signal; determining an electrical transfer function of the one or more processors; determining a closed-ear transfer function based on the first audio transfer function, the second audio transfer function and the electrical transfer function; and equalising the first audio signal based on a comparison between the closed-ear transfer function and an open-ear transfer function to generate an equalised first audio signal.

A propagation delay identification system for active noise cancelation for a vehicle audio system may include at least one sensor configured to transmit sensor data indicative of acceleration data, hammer data and microphone data, at least one output sensor configured to transmit an impulse response, and a processor. The processor may be programmed to receive the sensor data and pulse function, identify a propagation path delay between the microphone data and a cross-correlation between the acceleration data and hammer data, and generate a source pulse function. The processor further identify a secondary path delay based on an arrival time of peak energy of a convolution of the impulse response and filtered pulse function, and apply a binary limiter to a reference signal in response to the secondary path delay exceeding the propagation path delay to reduce boosting of an audio signal based on coherent reference and error signals.

A method for voice detection, the method may include (a) generating an in-ear signal that represents a signal sensed by an in-ear microphone and fed to a feedback active noise cancellation (ANC) circuit; (b) generating at least one additional signal, based on at least one out of a playback signal and a pickup signal sensed by a voice pickup microphone; and (c) generating a voice indicator based on the in-ear signal and the at least one additional signal.

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.

An active noise cancellation (ANC) system may include provisions for validating the accuracy of a modeled transfer characteristic stored in secondary path filters, which provides an estimate of the secondary path (i.e., the transfer function between a speaker and an error microphone). Using estimated anti-noise or music signals to adjust an error signal from the error microphone, a signal analysis controller may detect ANC instability or noise boosting. Such noise boosting may indicate the stored transfer characteristic in the secondary path filter does not accurately represent the actual secondary path. According, upon detection of noise boosting, the stored transfer characteristic of the secondary path filters may be modified.

A system and method for integrating a home media system and other home systems. As a non-limiting example, various aspects of this disclosure provide a system and method that flexibly and efficiently provide communication and/or resource sharing between a home media system and various other home systems.