ACTIVE NOISE REDUCTION DEVICE

Japanese Patent JP3545082

B2

PURPOSE: To provide a noise reduction device capable of rapidly and surely reducing a noise in space to be muffled without being affected by a noise state and an environmental state such as a temp. and humidity, etc.
CONSTITUTION: In the device that a control sound signal Y of a phase opposite to and the same amplitude as a noise signal X detected by a microphone 10 is generated by an ADF 32, and a control sound is generated from a speaker 14, and the filter coefficient W of the ADF 32 is updated successively by an operation part 40 so that a remaining noise signal (e) detected by the microphone 12 becomes minimum, a convergence coefficient operation part 46 successively calculating a convergence coefficient μ for updating the filter coefficient based on the square sum total ΣX2 of all noise signals is provided. Further, the filter coefficients (transfer functions Gs, Ge) etc., of a DF 34 operating the correction value II of the noise signal X and the DF 38 operating a reference signal R for calculating the filter coefficient are stored in transfer function storage parts 56, 58 at every environmental state beforehand dividing the environmental state of a duct 2, and an environment decision part 54 selects/sets a value according to the real environmental state.

Osamu Kato
Masaki Hase
Miki Goto

JP5288995A

July 21, 2004

March 13, 1995

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Nippon Vehicle Manufacturing Co., Ltd.

F01N1/00; F24F13/02; G10K11/16; G10K11/178; H03H21/00; H04R3/02; (IPC1-7): G10K11/178; F01N1/00; F24F13/02; G10K11/16; H03H21/00; H04R3/02

JP6130970A
JP6130969A
JP6193912A
JP6348284A
JP7056579A
JP5061481A
JP7028477A
JP6319189A
JP3237208A

Tsutomu Adachi

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