Electronic noise attenuation method and apparatus for use in effecting such method

An electronic noise attenuation apparatus for achieving attenuation of a sound wave propagated from at least one noise source in a given region within an area for a sound wave to be propagatable in a three dimensional direction by generating at least one additional sound wave about 180.degree. out of phase and having nearly equal sound pressure with the propagated sound wave to thereby produce sound interference between the propagated sound wave and said at least one additional sound wave in the given region within the propagatable area, said electronic noise attenuation apparatus comprising:

• noise detection means for detecting noise from said at least one noise source and converting the noise into an electrical noise signal;
• at least one additional sound wave generation means for generating at least one corresponding additional sound wave to cancel said propagated sound wave from the at least one noise source in the given region;
• a plurality of error sensors disposed in the given region, each error sensor detecting interference between the propagated sound wave from the at least one noise source and the at least one additional sound wave from the at least one additional sound wave generation means, each error sensor converting the interference into electrical interference signals;
• at least one adaptive digital filtering generating a drive signal based on the electrical noise signal and adaptive filter coefficients corresponding to each adaptive digital filter, wherein the drive signal corresponding to each adaptive digital filter drives a corresponding one of said at least one additional sound wave generation means;
• and
• control means for sampling the electrical noise signal and the electrical interference signals, for calculating at least first adaptive filter coefficients as a first set and second adaptive filter coefficients as a second set, each of the first set and second set minimizing the electrical interference signals based on electrical signals that are sampled in accordance with a given algorithm in each sampling, and for updating the filter coefficients of each adaptive digital filter of the at least one adaptive digital filter by the first adaptive filter coefficients and the second adaptive filter coefficients, wherein said control means includes means for dividing said plurality of error sensors into at least a first error sensor group comprising at least one error sensor and a second error sensor group comprising at least one error sensor, the means for calculating the first adaptive filter coefficients being based on only the electrical interference relating to said first error sensor group at a first sampling time, the means for calculating the second adaptive filter coefficients being based on only the electrical interference signals relating to said second error sensor group at a next sampling time, and the calculating means repeatedly executing each sampling sequentially.

An electronic noise attenuation method comprising the steps of:

• (a) sampling a noise signal to form a digital noise signal at a present sample time;
• (b) generating reference signals based on the digital noise signal at the present sample time and predetermined filter coefficients;
• (c) selecting an error signal at the present sample time from a plurality of error signals generated by a plurality of error sensor groups;
• (d) generating adaptive filter coefficients for the present sample time based on adaptive filter coefficients of a previous sample time, the reference signals of the present sample time and the selected error signal of the present sample time;
• (e) generating separate drive signals for controlling a plurality of sound wave generating means based on the digital noise signal of the present sample time and the generated adaptive filter coefficients of the present sample time, said plurality of sound wave generating means includes a plurality of speakers;
• (f) applying the separate drive signals to the plurality of speakers, outputs of the speakers attenuating the noise.
• (g) repeating steps (a) through (f) for a subsequent sample time, wherein the error signal selected at the subsequent sample time is from a different error sensor group that the error sensor group used in the present sample time.

An electronic noise attenuation apparatus comprising:

• a sensor detecting a noise from a noise source and generating a digital noise signal;
• a plurality of sound wave generating means each outputting an attenuating wave for attenuating the noise, said plurality of sound wave generating means includes a plurality of speakers;
• a plurality of error sensing groups each containing at least one error sensor, each error sensor group generating an error signal in response to the detection of interference between the noise and outputs from the plurality of speakers;
• a plurality of adaptive digital filters, each outputting a speaker signal to one of the plurality of speakers based on the digital noise signal and adaptive filter coefficients;
• and
• a controller generating the adaptive filter coefficients for each one of the plurality of speakers based on the error signal from one of the plurality of error sensor groups and a reference signal, wherein the reference signal is generated from the digital noise signal and predetermined filter coefficients, and the error signal selected from generating current adaptive filter coefficients is from a different error sensor group than the error sensor group used to generate the previous adaptive filter coefficients.

An electronic noise attenuation method for detecting noise from at least one noise source, and for generating at least one additional vibration wave against the vibration wave propagated from said at least one noise source to an object, the at least one additional vibration wave being generated by at least one additional vibration wave generation means and being about 180.degree. out of phase and having substantially equal amplitude with the propagated vibration wave from the at least one noise source, thereby causing the propagated vibration wave and the at least one additional vibration wave to interfere with each other so as to attenuate the propagated vibration wave, said electronic vibration attenuation method comprising the steps of:

• (a) arranging on said object a plurality of error sensors, each error sensor detecting an interference vibration produced by interference between said propagated vibration wave from said at least one noise source and each additional vibration wave from said at least one additional vibration wave generation means;
• (b) dividing said plurality of error sensors into at least a first error sensor group comprising at least one of the plurality of error sensors and a second error sensor group comprising at least one of the plurality of error sensors, the first error sensor group and the second error sensor group containing different error sensors of the plurality of error sensors;
• (c) detecting and sampling said noise and an output signal from the first error sensor group at a present sampling time;
• (d) calculating a set of first adaptive filter coefficients for at least one adaptive digital filter based on said noise and the output of only the first error sensor group and in accordance with a given algorithm to minimize the output signal of said first error sensor group, and updating the adaptive filter coefficients of each adaptive digital filter of the at least one adaptive digital filter by said set of first adaptive filter coefficients;
• (e) detecting and sampling said noise and an output signal from the second error sensor group at a next sampling time;
• (f) calculating a set of second adaptive filter coefficients for the at least one adaptive digital filter based on said noise and the output of only the second error sensor group and in accordance with the given algorithm to minimize the output signal of said second error sensor group, and updating the adaptive filter coefficients of each adaptive digital filter of the at least one adaptive digital filter by said set of second adaptive filter coefficients;
• (g) repeatedly executing steps (c) through (f) sequentially for each group of said divided plurality of error sensors to thereby update the adaptive filter coefficients of each adaptive digital filter;
• and
• (h) generating the at least one additional vibration wave at every sampling time by producing drive signals to drive each of said at least one additional vibration wave generation means by convolution of the detected noise and updated filter coefficients.

An electronic noise attenuation apparatus for achieving attenuation of a vibration wave propagated from at least one noise source to an object by generating at least one additional vibration wave about 180.degree. out of phase and having nearly equal amplitude with the propagated vibration wave to produce vibration interference between the propagated vibration wave and said at least one additional vibration wave, said electronic vibration attenuation apparatus comprising:

• noise detection means for detecting noise from the at least one noise source and converting the noise into an electrical noise signal;
• at least one additional vibration wave generation means for generating corresponding at least one additional vibration wave to cancel said propagated vibration wave propagating from the at least one noise source to the object;
• a plurality of error sensors disposed on the object, each error sensor detecting interference between the propagated vibration wave from the at least one noise source and the at least one additional vibration wave from the at least one additional vibration wave generation means, each error sensor converting the interference into electrical interference signals;
• at least one adaptive digital filter generating a drive signal based on the electrical noise signal and adaptive filter coefficients corresponding to each adaptive digital filter, wherein the drive signal corresponding to each adaptive digital filter drives a corresponding one of the at least one additional vibration wave generation means;
• and
• control means for sampling the electrical noise signal and the electrical interference signals, for calculating at least first adaptive filter coefficients as a first set and second adaptive filter coefficients as a second set, such that each of the first set and second set minimize the electrical interference signals based on electrical signals that are sampled in accordance with a given algorithm in each sampling, and for updating the filter coefficients of each adaptive digital filter of the at least one adaptive digital filter by the first adaptive filter coefficients and the second adaptive filter coefficients, wherein said control means includes means for dividing said plurality of error sensors into at least a first error sensor group comprising at least one error sensor and a second error sensor group comprising at least one error sensor, the means for calculating the first adaptive filter coefficients being based on only the electrical interference signals relating to said first error sensor group at a first sampling time, the means for calculating the second adaptive filter coefficients being based on only the electrical interference signals relating to said second error sensor group at a next sampling time, and the calculating means repeatedly executing each sampling sequentially.