To reduce structural load and installation work.
A canceling-purpose acoustic signal s (n) is made by making a noise reference signal x (n) pass through a filter 5 with a transfer function W, and is power-amplified by a power amplifier 7 after processed by D/A converter, and is made to drive a canceling loudspeaker 2 located near the right ear of a subject person for the noise control. The sound picked up by an error detecting microphone 1 located near the right ear of the subject person for the noise control is amplified by a microphone amplifier 8, and then A/D converted by an A/D converter 9 for obtaining an error signal y (n). A filter 21 is provided in which an estimate C' of a transfer function C from an input point of a power amplifier 7 to an output point of the microphone amplifier 8 is set, and only the noise component is taken out by subtracting the signal s (n) passed though the filter 21 from the signal y (n) by means of an arithmetic and logic unit 22 for being outputted to a filter 5. In the filter 5, W=-1/C" is set as an estimation value C of the transfer function C.
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