To provide a noise reduction device adopting an FF (Feed Forward) control system effectively exerting a noise reducing effect under an environment without satisfying a limit of time causality in a positional relation between a noise detecting microphone, a speaker and a control point (silencing center), in passenger seats in an aircraft, etc.
In this noise reduction device for controlling noise up to a prescribed upper limited frequency, a distance from a noise source 610 to the control point X is set longer than a distance subtracted by one-half wavelength from a distance added with a distance from the noise source 610 up to the noise detecting microphone 620, a distance equivalent to time summed with each delay time of the noise detecting microphone 620, a noise control device 630 and a control speaker 630 and a distance from a control speaker 640 up to the control point X, where one wavelength is a period corresponding to the upper limited frequency.
ASAO KEISHI
KANO HIROYUKI
Hiroki Naito
Daisuke Nagano
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