An active noise control system includes an error adder that generates an error signal by adding an output of a left-seat left microphone and an output of a left-seat right microphone, an adaptive filter that generates a noise canceling sound from a reference signal by performing an adaptive operation using the reference signal and the error signal, a left channel gain adjustment section that adjusts a gain of the noise canceling sound to be output to a left-seat left speaker, and a right channel gain adjustment section that adjusts a gain of the noise canceling sound to be output to the left-seat right speaker. A ratio between the gains of the left channel gain adjustment section and the right channel gain adjustment section matches a ratio between loudness levels of noise transmitted to the output of the left-seat left microphone and the output of the left-seat right microphone.

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.

An integrated circuit for implementing at least a portion of a personal audio device may include an output for providing an output signal to a transducer, wherein the output signal includes a pilot signal, a microphone input for receiving a microphone signal from a microphone indicative of an output of the transducer, and a processing circuit. The processing circuit may be configured to implement a pilot signal control to apply an adjustment to the pilot signal as necessary to maintain the pilot signal at a substantially constant magnitude regardless of proximity of the transducer to a pinna and implement a proximity determination block configured to determine proximity of the transducer to the pinna based on the adjustment.

Active noise control systems and methods are disclosed that include generating with a first sub-system, anti-noise that is configured to reduce or cancel noise occurring at a listening position. Generating with a second sub-system, anti-noise that is configured to reduce or cancel noise occurring at the listening position. The first active noise control sub-system has a higher robustness than the second active noise control sub-system.

The present invention relates to methods, apparatus and systems for audio playback via a personal audio device following a biometric process. A personal audio device may be used to obtain ear model data for authenticating a user via an ear biometric authentication system. Owing to that successful authentication, the electronic device is informed of the person who is listening to audio playback from the device. Thus the device can implement one or more playback settings which are specific to that authorised user.

Engine order cancellation (EOC) systems generate feed forward noise signals based on the engine or other rotating shaft RPM and use those signals and adaptively configured W-filters to reduce the in-cabin SPL by radiating anti-noise through speakers. An EOC system may include a drive mode detector for detecting different vehicle drive modes based on an analysis of signals indicative of current vehicle operating conditions. Upon detection, the EOC system may adaptively adjust various tuning parameters for the EOC algorithm based on the current vehicle drive mode. The EOC system may also selectively target different sets of engine orders for noise cancellation according to the current vehicle drive mode based on which engine orders are dominant during that drive mode.

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 signal representative of the undesired sound present in the target space. Sound reduction further includes producing, based on the cancelling signal, sound to destructively interfere with the undesired sound present in the target space, producing sound based on an audio signal in the target space, and removing from the reference signal, based on the audio signal, a reference signal component representative of audio signal components transferred via a feedback path from the transducer to the reference sensor.

Audio (noise source) is output as a cancellation sound through a variable filter and a first filter, and transmitted to the second filter. A subtractor subtracts an output of a second filter from an output of a microphone, and an adaptive algorithm execution unit updates a transfer function of the variable filter so that the subtracted result becomes zero (0). A transfer function A for the first filter is a transfer function which can cancel noise at a position of a user's ear by setting, as the cancellation sound, a sound obtained by applying the transfer function A to audio at the time of learning, and a transfer function B for the second filter is a transfer function which can eliminate, for the cancellation sound, a difference between a sound obtained by applying the transfer function B to audio and the output of the microphone.

A noise cancellation filter structure for a noise cancellation enabled audio device, in particular headphone, comprises a noise input for receiving a noise signal and a filter output for providing a filter output signal. A first noise filter produces a first filter signal by filtering the noise signal and a second noise filter produces a second filter signal by filtering the noise signal. The second noise filter has a frequency response with a non-minimum-phase, in particular maximum-phase. A combiner is configured to provide the filter output signal based on a linear combination of the first filter signal and the second filter signal.

An active noise cancellation system for reducing unwanted noise in a target area by attenuating a disturbance noise signal (d(n)), which is the remaining noise in the target area originated from an ambient noise signal (x(n)) present in the vicinity of the target area that is transferred to the target area via a main path described by a transfer function P(z)), the active noise cancellation system including a processing unit that implements an ANC-controller which is configured to provide a control signal (y(n)) for controlling a speaker in the target area in order to generate an acoustic signal (y(n)) that destructively overlaps with the disturbance noise signal (d(n)) and thereby attenuates the same.