An apparatus for noise reduction in audio signal processing includes a power amplifier, a zero-crossing detector, and a threshold detector. The power amplifier has an input signal terminal for receiving an audio input signal and an output signal terminal. The audio input signal is a digital-to-analog converted version according to a version of a digital audio signal. The power amplifier has an analog gain which is controllable in response to an analog gain control signal. The zero-crossing detector determines a zero-crossing detection signal according to an internal signal provided between the input signal terminal and the output signal terminal. The threshold detector determines a gain setting according to the digital audio signal and the zero-crossing detection signal to generate the analog gain control signal indicating the gain setting, wherein the threshold detector controls the analog gain of the power amplifier according to the analog gain control signal.

A speaker system uses destructive wave interference to generate “dead spots” with respect to an audio presentation. The signal for the dead spot generating device can be an inverted signal generated using the audio signal. In one embodiment, the inverted signal is generated using the audio signal, an indication of loudness at one or more active speakers, and a determination of the characteristics of the sound path from the one or more active speakers (including delay and attenuation).

An active noise cancelling system (20) comprising: an earphone (8′) comprising: an electro-acoustic driver (11); and at least one sensing microphone (12, 13); tunable active noise cancelling circuitry (7) operative to receive a signal from the at least one sensing microphone (12, 13), the tunable active noise cancelling circuitry (7) being pre-configured in a standard tuning for a reference ear and comprising at least one noise-control filter (14, 15); and a tuning module (24) operative to configure the earphone (8′) for an individual wearer by: comparing acoustic coupling of the earphone (8′) to the individual wearer's ear with acoustic coupling to the reference ear to determine a deviation in acoustic coupling; and using the determined deviation in acoustic coupling to modify the tunable active noise cancelling circuitry (7) by a predetermined degree based on the determined deviation in acoustic coupling.

Method for automatably or automated tuning at least one operational parameter of an engine-order-cancellation (“EOC”) apparatus, the EOC apparatus being operable on the basis of a number of operational parameters, comprising the steps of: providing a defined tuning rule for automatably or automated tuning at least one operational parameter of an EOC apparatus, and automatably or automated tuning the at least one operational parameter of the EOC apparatus on basis of the provided tuning rule.

A method for tuning filter parameters of a noise cancellation enabled audio system with an ear-mountable playback device comprising a speaker and a feedback noise microphone located in proximity to the speaker comprises provision of acoustic transfer functions between the speaker and the feedback noise microphone, between the speaker and an eardrum, between an ambient sound source and the eardrum and between the ambient sound source and the feedback noise microphone. The parameters of a feedback filter function, which is designed to process a feedback noise signal, are tuned. A noise cancellation performance of the audio system at the eardrum is determined based on each of the acoustic transfer functions and on the feedback filter function.

A speaker system uses destructive wave interference to generate “dead spots” with respect to an audio presentation. The signal for the dead spot generating device can be an inverted signal generated using the audio signal. In one embodiment, the inverted signal is generated using the audio signal, an indication of loudness at one or more active speakers, and a determination of the characteristics of the sound path from the one or more active speakers (including delay and attenuation).

A sound output device according to an embodiment includes: an acoustic path (70) and a microphone (100b). The acoustic path connects a first space (54b) formed on a front surface of a driver unit (106) and the outside of a housing (50b) including the driver unit separately from a second space (55b) formed on a back surface of the driver unit. The microphone is disposed in the vicinity of an opening where the acoustic path is connected to the outside of the housing.

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.

For example, a controller of an Active Acoustic Control (AAC) system may be configured to process input information, the input information including AAC configuration information corresponding to a configuration of AAC in a sound control zone; a plurality of noise inputs representing acoustic noise at a plurality of noise sensing locations; and a plurality of residual-noise inputs representing acoustic residual-noise at a plurality of residual-noise sensing locations within the sound control zone. For example, the controller may determine a sound control pattern to control sound within the sound control zone based on the AAC configuration information, the plurality of noise inputs, and the plurality of residual-noise inputs. For example, the controller may output the sound control pattern to a plurality of acoustic transducers.

The present disclosure provides an automobile and a noise reduction method thereof, wherein the automobile includes an automobile body having an accommodating space and a plurality of doorways communicating with the accommodating space, a door configured for closing each doorway, at least one seat, at least one sound collecting device mounted on the automobile body at a periphery of each door, at least two sound devices mounted on at least one seat, and a processor electrically connected to all the sound devices and all the sound collecting devices. A noise reduction system composed of all the sound devices, all the sound devices, and the processor can perform noise reduction on a preset area in the accommodating space. The embodiments of the present invention expand and reuse a system composed of original sound collecting devices and sound devices in the automobile, without stacking materials on the doors or the automobile body.