A system includes a microphone unit coupled to a roof of an autonomous vehicle. The microphone unit includes a microphone board having a first opening. The microphone unit also includes a first microphone positioned over the first opening and coupled to the microphone board. The microphone unit further includes an accelerometer. The system also includes a processor coupled to the microphone unit.

An active noise control device includes a control signal generating unit including a first adaptive filter configured to generate a control signal by performing a filtering process on a reference signal corresponding to noise, an identifying unit configured to identify a peak frequency in an impedance frequency characteristic of an actuator, a peak frequency storage unit configured to store an initial peak frequency of the actuator, a first determination unit configured to determine whether or not a difference between the peak frequency currently identified and the initial peak frequency is greater than or equal to a threshold value, and a control unit configured to change a characteristic of the control signal generated by the control signal generating unit when the first determination unit determines that the difference is greater than or equal to the threshold value.

An audio processing system includes at least one first microphone, at least one adaptive filter, and a processor. The at least one first microphone acquires a first audio signal and outputs a first signal based on the first audio signal. The first audio signal includes at least one of a first audio component generated at a first position and a second audio component generated at a second position different from the first position. The first signal is input to the at least one adaptive filter. The at least one adaptive filter outputs a passing signal based on the first signal. The processor, when executing a program stored in a memory, performs: making a determination of which of the first audio component and the second audio component the first audio signal includes more; and controlling a filter coefficient of the adaptive filter based on a result of the determination.

Sound reduction includes producing an error signal representative of sound present in a target space, producing a reference signal corresponding to undesired sound present in the target space, and producing, based on the reference signal and the error signal a cancelling output signal representative of the undesired sound present in the target space. The method further includes producing, based on the cancelling output signal, sound to destructively interfere with the undesired sound present in the target space, and limiting the amplitude or power of at least one of the reference signal, the error signal and the cancelling output signal if a first condition is met, the at least one signal under examination is at least one of the reference signal, the error signal and the cancelling output signal, and fully or partially suspending the active noise controller update mechanism if a second condition is met.

A computer-implemented method for determining whether the noise floor of a sensor is deviated from an expected value, comprising the steps of: receiving a sensor signal from a sensor; determining a plurality of power spectral densities from a plurality of successive frames of samples of the sensor signal, each of the plurality of power spectral densities being determined from a respective frame of the plurality of successive frames, each power spectral density being comprised of a plurality of frequency bins, each frequency bin being associated with a power of the respective frame at the frequency of the respective frequency bin, wherein each successive frame of the plurality of successive frames differs by at least one sample; identifying a minimum power of the plurality of power spectral densities; and determining whether the minimum power exceeds a threshold value.

In certain aspects, an active noise control (ANC) method and system for a headphone are disclosed. It is determined whether a music signal is played by a speaker of the headphone. Responsive to the music signal not being played by the speaker and a noise level of an ambient noise signal being greater than a noise threshold, a set of noise feedforward (FF) signals is obtained based on a set of FF microphone signals acquired by a set of FF microphones of the headphone. A noise feedback (FB) signal is obtained based on a first FB microphone signal acquired by a FB microphone of the headphone. A set of leakage monitoring parameters is obtained based on the set of noise FF signals and the noise FB signal. A set of FF filter parameters for a set of FF filters is adjusted based on the set of leakage monitoring parameters.

An audio device with acoustic echo cancellation includes a device cabinet having a cabinet interior; a first open back driver receiving a first open driver input from an audio source; a second open back driver receiving a second open driver input from the audio source, wherein the first open back driver and the second open back driver are acoustically coupled to the cabinet interior; a reference microphone located in the cabinet interior to record a reference microphone signal based on sound emitted within the cabinet interior by the first open back driver and the second open back driver based on the first open driver input and the second open driver input, respectively; and an acoustic echo cancellation block subtracting a representation of the reference microphone signal from a representation of a set of input microphone signals to provide an echo-cancelled output.

A howling detector is described that is configured to receive an input signal and to determine measure of the linearity of a logarithmic representation of the energy of the input signal. In some examples, this triggers gain adjustment (e.g. of a noise control unit) and, in some further examples, the amount of the gain adjustment may be based on an estimation of the maximum stable gain of a noise control unit.

A method performed by an audio output device is provided for detecting instabilities and taking mitigating actions. Specifically, an A-weighted dBA level of a raw feedback signal exceeding a threshold level trigger, at least, muting the driver. The described methods apply to detecting instabilities across a broad frequency spectrum.

One example method includes performing sound quality operations. Microphone arrays are used to cancel background noise and to enhance speech. With arrays at each environment of each user participating in a call, a first microphone array can cancel or suppress background noise and a second array can generate enhanced speech for transmission to other users. Thus, for user, the audio signal output by the user's device includes an anti-noise signal to cancel background noise present in the user's environment and enhanced speech from other users.