An active noise reduction device reduces noise in a space in an automobile. The active noise reduction device includes: a reference signal input terminal that receives a reference signal outputted by a reference signal source and having a correlation with the noise, the reference signal source being attached to the automobile; a compressor that compresses and outputs the reference signal received by the reference signal input terminal and having an amplitude greater than or equal to a threshold; an adaptive filter unit that applies an adaptive filter to the reference signal outputted from the compressor to generate a canceling signal to be used to output a canceling sound for reducing the noise; and a filter coefficient updater that updates a coefficient of the adaptive filter.

The present invention provides an improved noise separation hybrid type ANC system, which includes a reference audio receiving device, an error audio receiving device, an audio output device, and an audio processing device. The audio processing device includes a feed-forward noise cancellation filter module, a feedback noise cancellation filter module, a mixer, a noise shaper, a first infinite impulse response filter, and a second infinite impulse response filter. When the noise bandwidth detector detects irregular noise, it adjusts the coefficient of the first infinite impulse response filter to set it as a low-pass filter; when regular noise is detected, the coefficient of the second infinite impulse response filter is adjusted to set it as a band-pass filter.

A transfer function of a first variable filter is updated to output, from an output of a first seat microphone, a cancel sound that minimizes a level of a signal obtained by subtracting an output of an auxiliary filter that generates a correction signal for correcting a difference between positions of the first seat microphone and the first seat. In the ICC mode in which the uttered voice of the user in the first seat is output from a second seat speaker, a selector sets an uttered voice Dp output from the second seat speaker as an input to the first variable filter, and in the non-ICC mode, the selector sets an output sound of a second seat audio source output from the second seat speaker as an input to the first variable filter. The uttered voice Dp is generated by removing a component of the cancel sound from the output of the first seat microphone.

A first variable filter receives a sound of a second seat audio source as an input and generates a cancel sound for canceling the sound of the second seat audio source at a first seat. The transfer functions of the first variable filter and the second variable filter are updated such that the level of a signal obtained by subtracting the output of the auxiliary filter that generates a correction signal for correcting the difference between the positions of the first seat microphone and the first seat and the output of the second variable filter that receives the sound of the first seat audio source from the output of the first seat microphone is minimized. While the level of the signal exceeds a threshold, the signal is relayed to the second seat as a spoken voice.

An active noise reduction device includes an impulsive signal generator that generates an impulsive signal, a signal output terminal that outputs the impulsive signal to a loudspeaker, and a signal detector that detects a rising signal and a falling signal from a microphone signal outputted from a microphone collecting sound. The device also includes a connection determiner that determines, based on respective peak values of the rising signal detected and the falling signal detected, whether or not the loudspeaker is connected to the signal output terminal. The device further includes a polarity determiner that determines a connection polarity between the loudspeaker and the signal output terminal based on respective timings of the rising signal and the falling signal with respect to the impulsive signal, when it is determined that the loudspeaker is connected to the signal output terminal.

An illustrative hearing device includes a housing configured to be partially inserted into an ear canal; an acoustic transducer having an oscillator element configured to generate sound waves, the housing accommodating the acoustic transducer inside an inner volume of the housing; and a sound outlet provided at the housing and configured to enable propagation of sound waves from the inner volume into the ear canal. The acoustic transducer and the housing are configured such that an output impedance of the hearing device measured at the sound outlet has a value of at most 3.5.Math.10.sup.7 kg/(m.sup.4.Math.sec) within a frequency bandwidth of at least 50 Hz comprised in a frequency range between 1000 Hz and 2000 Hz.

A method of calibrating a feedback-based noise cancellation system of an ear device may involve obtaining a measured plant response of the ear device, obtaining a reference plant response value and determining a plant response variation between the reference plant response value and a value corresponding to the measured plant response. The method may involve obtaining a measured a coupler response of the ear device, obtaining a reference coupler response value and determining a coupler response variation between the reference coupler response value and a value corresponding to the measured coupler response. The method may involve determining, based at least in part on the plant response variation and the coupler response variation, a microphone signal gain correction factor and applying the microphone signal gain correction factor to ear device microphone signals that are input to a feedback loop of the feedback-based noise cancellation system.

A method for operating a hearing aid includes providing the hearing aid with an ANC unit having a feedforward unit outputting a feedforward signal for suppressing external interference noises penetrating from the outside into an auditory canal of a user of the hearing aid. The ANC unit has a feedback unit outputting a feedback signal for suppressing internal interference noises present inside the auditory canal. The hearing aid has a signal processing unit which has a settable amplification and which amplifies an input signal of the hearing aid and outputs it as an amplified signal. The feedback signal is used as a measure of the user's own voice, and the amplification of the signal processing unit is set depending on the feedback signal and thus also depending on the user's own voice. A hearing aid having a control unit for executing the method is also provided.

Detecting a divergence in an adaptive system includes the steps of determining a power of a component of an error signal at a first frequency, the component being correlated to a noise-cancellation signal, the noise-cancellation signal being produced by an adaptive filter and being configured to cancel noise within a predetermined volume when transduced into acoustic signal, wherein the error signal represents a magnitude of a residual noise within the predetermined volume; determining a time gradient of the power of the component of the error signal; and comparing a metric to a threshold, wherein the metric is based, at least in part, on a value of the time gradient of the power of the component of the error signal over a period of time.

Described herein is a speakerphone system (system) comprising: at least one loudspeaker, the loudspeaker adapted to generate mechanical vibrations on an enclosure of the system; at least one microphone (mic) adapted to convert an input sound acoustic signal into an input sound electrical signal and adapted to convert the mechanical vibrations into a mechanical vibrations electrical signal, and to output both of the input sound electrical signal and the mechanical vibrations electrical signal as a mic output signal; at least one mechanical vibration sensor (MVS) adapted to convert the mechanical vibrations to a mechanical vibration error signal to output the mechanical vibration error signal as an MVS output signal; and circuitry adapted to subtract the MVS output signal from the mic output signal and output the resultant signal as a speakerphone output signal.