A processor is configured to perform headphone playback with a playback audio signal. The processor produces a feedback signal from an internal microphone, compresses the feedback signal according to a variable compressor setting, and determines a context of usage of the headphone, as being one of running or jogging, transportation, and critical listening. In response, the processor changes the variable compressor setting and drives the headphone speaker with the compressed feedback signal combined with the playback audio signal. Other aspects are also described and claimed.

An active noise control device controls a speaker so as to output a canceling sound for canceling noise transmitted from a vibration source. The active noise control device includes a control signal generating unit configured to perform signal processing on a basic signal corresponding to a predetermined frequency by a feedback filter and a extraction filter, which is an adaptive notch filter, to generate a control signal that control the speaker, a secondary path filter updating unit configured to update sequentially and adaptively a secondary path filter, and a feedback filter setting unit configured to set the feedback filter based on the secondary path filter.

A noise reduction device includes a processor that converts a noise signal collected by a microphone disposed in a control space into a noise signal in a frequency domain, a storage that stores the converted noise signal in the frequency domain as a reference signal, and a signal generator that generates a noise reduction signal for reducing the noise signal collected by the microphone at a control position of the control space. The processor determines whether or not the noise signal is non-stationary noise based on a frequency characteristic of the converted noise signal in the frequency domain and a frequency characteristic of the reference signal. When it is determined that the noise signal is the non-stationary noise, the processor controls the signal generator so as to cancel generation of the noise reduction signal.

A method for reducing noise includes: obtaining an air conduction noise reduction parameter and a bone conduction noise reduction parameter, the air conduction noise reduction parameter being obtained by integrating an air conduction parameter of the current frame and an air conduction noise parameter of the current frame, and the bone conduction noise reduction parameter being obtained by integrating a bone conduction parameter of the current frame and a bone conduction noise parameter of the current frame; calculating a priori signal-to-noise ratio of air-bone integration according to the bone conduction parameter of the current frame and the air conduction noise parameter of the current frame; and performing noise reduction operation according to the priori signal-to-noise ratio of air-bone integration, the air conduction noise reduction parameter and the bone conduction noise reduction parameter.

An active noise reduction device includes: an adaptive filter that generates a cancelling signal by applying an adaptive filter to a reference signal that has a correlation with noise in a space in an automobile, the cancelling signal being used to output a cancelling sound for reducing the noise; and a filter coefficient updater that calculates a coefficient of the adaptive filter based on a predetermined update equation. At a first timing at which the output of the cancelling sound is started, the filter coefficient updater uses a first coefficient as an initial value of the update equation, the first coefficient being the coefficient of the adaptive filter calculated by the filter coefficient updater at a second timing that is prior to the first timing.

An active noise control device includes a determination unit configured to determine whether an abnormality has occurred in an acceleration sensor based on a direct-current component of a reference signal acquired by the acceleration sensor attached to a vehicle, and a control unit configured to, when the determination unit determines that an abnormality has occurred in any of a plurality of the acceleration sensors, stop generation of the control signal based on the reference signal acquired by the acceleration sensor that has been determined to have the abnormality, and stop updating a filter coefficient of an adaptive filter configured to perform the filtering process on the reference signal acquired by the acceleration sensor that has been determined to have no abnormality.

In at least one embodiment, an active noise cancellation (ANC) system is provided. The ANC system includes at least one microphone, a first filter, a first controllable filter, and at least one controller. The at least one microphone provides an error signal indicative of noise and an anti-noise sound within the cabin. The first filter modifies a transfer function between the at least one microphone and at least one remote microphone location to generate an estimated remote microphone error signal based at least on the error signal. The first controllable filter generates the anti-noise signal based on the estimated remote microphone error signal. The controller receives receive a first signal indicative of the vehicle exhibiting a fast-adapting event controls the first filter to execute a predetermined filter based on the first signal to reduce a group delay associated with the first filter.

An integrated circuit may include an output for providing an output signal to a transducer including both a source audio signal for playback to a listener and an anti-noise signal for countering the effect of ambient audio sounds in an acoustic output of the transducer, an error microphone input for receiving an error microphone signal indicative of the output of the transducer and the ambient audio sounds at the transducer, and a processing circuit. The processing circuit may implement a feedback path comprising a feedback filter having a response that generates a feedback anti-noise signal based on the error microphone signal, the feedback filter comprising a plurality of biquad filters and wherein the anti-noise signal is generated from the feedback anti-noise signal and an event detection and oversight control that detects that an ambient audio event is occurring that could cause the feedback filter to generate an undesirable component in the anti-noise signal, and controls filter coefficients of one or more of the plurality of biquad filters to reduce the undesirable component.

To reduce engine noise in the cabin of an aircraft a plurality of error microphones is deployed at predetermined locations within the cabin to produce error microphone response signals associated with the engine noise in the cabin. Engine vibration inputs are obtained from sensors coupled to the aircraft engines. A processor is used to code the error microphone response signals into an encoded modal response in the cabin through a coding matrix. A processor is used to apply an adaptive filter to determine a plurality of modal signals needed to cancel the encoded modal response in the cabin. A processor is used to decode the modal signals into speaker input signals through a decoding matrix. Speaker input signals are then sent to a plurality of speakers to reduce the engine noise in the cabin.

An electronic system includes a fan module, an embedded controller, a reference microphone, an error microphone, an active noise cancellation controller, and a micro speaker module. The reference microphone outputs a wide-band noise signal associated with the operation of the fan module. The error microphone outputs an error signal by detecting the noise level of the electronic system. According to the wide-band noise signal, the error signal and the fan information provided by the embedded controller, the active noise cancellation controller provides a speaker control signal by calculating narrow-band and wide-band noises of the fan module, and drives the micro speaker module to provide a noise cancellation signal which is adjusted according to the wind pressure under the current fan speed of the fan module. The error signal may be reduced to zero by adaptively adjusting the noise cancellation signal for canceling the noises in the electronic system.