Nissan Motor Company Limited

Hitachi, Ltd.

Other

Bridgestone Corporation

Hitachi Plant Engineering Construction Co., Ltd.

Akio Kinoshita

Kazuhiro Doi

Kenichiro Muraoka

Noriharu Sato

Tsutomu Hamabe

Minoru Takahashi

Keiichiro Mizuno

Yoshiharu Nakaji

Tanetoshi Miura

Hareo Hamada

Isutomu Hamabe

An active noise eliminating system comprises microphones for detecting residual noise, speakers for generating noise elimination sound for interference with the residual noise, a noise generating condition sensor for generating noise condition, a controller for generating noise elimination signals inputted to the speakers and determined by the detected residual noise signals and the detected noise condition signal in accordance with a control algorithm including transfer functions between the speakers and microphones respectively. The transfer functions are updated on the basis of a test signal generated when noise sound diverges.

Active noise eliminating system

An apparatus for active reduction of noises transmitted from a noise source into a space. The active noise reduction apparatus comprises residual noise sensors for detecting the residual noises in the space. A reference signal is produced based upon the noise generating condition of the noise source. The reference signal is used, along with the detected residual noises, to drive control sound sources so as to reduce the noises in the space. A filter is adjusted to correspond to acoustic transfer characteristics between the control sound sources and the residual noise sensors. An identification sound is generated to correspond to the background noise level detected in the space and to the spectral distribution of the noises transmitted into the space. The coefficients of the filter are updated according to acoustic transfer characteristics between the control sound sources and the residual noise sensors. The acoustic transfer characteristics are obtained based upon the identification sound and the residual noises.

Active noise reduction apparatus

An apparatus for reducing noise for an interior of enclosed space, e.g., a vehicular compartment using an FIR adaptive digital filter is disclosed in which a control circuit is provided which outputs drive signals to a plurality of loud speakers which generate control sounds to interfer with a noise sound propagated in the interior so that a performance function including terms of residual noise signals output from residual noise signal detecting microphones and drive signals to the loud speakers is minimized and contributivity of the drive signals to the performance function is changed according to an occurrence of divergence in the noise reducing apparatus.

Apparatus for actively reducing noise for interior of enclosed space

In an apparatus for reducing noises in a space, signals related to noise generating conditions of a plurality of noise sources are detected, a signal component of the detected signals is selected on the basis of determination of which signal component is predominant over the other signal component in the noises in the space, and the selected signal component is filtered through adaptively determined filter coefficients to output drive signals to control sound source, the filter coefficients being updated through a control algorithm so as to reduce a residual noise of a residual noise detector such as microphones. The signal components to be selected include a signal component having a relatively high auto-correlated function characteristic and a signal component having a random characteristic.

Apparatus for reducing noise in space applicable to vehicle compartment

A method for electrically attenuating a noise in an area for a sound wave to be propagatable in a three dimensional direction by making up a drive signal from the information on the noise and previously given filter coefficients by use of an adaptive digital filter and then generating an additional sound wave in accordance with the drive signal for cancellation of the noise. In the electric noise attenuation method, there are provided in a given region for noise attenuation, first and second error sensor groups for detecting an interference sound wave produced between the noise and additional sound wave, at a sampling time, a filter coefficient is calculated based on the information relating to the first error sensor group, at the next sampling time, another filter coefficient is calculated based on the information relating to the second error sensor group, and these operations are repeatedly executed sequentially for each error sensor to thereby update the filter coefficient of the adaptive digital filter.

Electronic noise attenuation method and apparatus for use in effecting

Growing community of inventors

Fujisawa, Japan

Akio Kinoshita