Wenderoth, Lind & Ponack
Electronic attenuator
 An electronic attenuator uses a speaker which is sheet-like in shape and is made of a piezoelectric material for generating a reversal sound. The attenuator uses a microphone installed in a noise transmittable space for detecting a noise and uses a control circuit for generating a reversal sound signal having a reverse phase and same sound pressure in relation to a noise on the basis of the noise signal detected by the microphone. The speaker receives the reversal sound signal from the control circuit and emits the reversal sound to the noise transmittable space so as to cancel the noise signal detected by the microphone. This electronic attenuator solves the problems of space required for the installation of a speaker, and reduces manufacturing costs and the like. 
Daikin Industries, Ltd.
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Hiroyuki
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