| 摘要 |
PROBLEM TO BE SOLVED: To suppress an echo caused by words spoken by a user, and a sound emitted from an acoustic device used by a user at a seat of an aircraft, etc., and to effectively reduce noise in the surrounding. SOLUTION: A noise reducing device includes a plurality of noise source microphones M1 to M4 that detect noise, an adaptive digital filter 332 that generates a control sound signal for canceling the noise detected by the noise source microphones M1 to M4 at a control center in a control space, a filter coefficient calculation part 333 that calculates a filter coefficient of the adaptive digital filter 332, and a speaker 340 that outputs a control sound based on the control sound signal. The plurality of noise source microphones M1 to M4 are arranged in the control space or its vicinity. The filter coefficient calculation part 333 sets control coefficients k1 to k4 related to distances d1 to d4 between the mouth of the user and the noise source microphones M1 to M4 for each of the plurality of noise source microphones M1 to M4 to perform weighting of detected values, and generates the control sound. COPYRIGHT: (C)2011,JPO&INPIT
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