To damp or vibrate a wall body of an intake system, and effectively reduce the intake noise, by mounting a piezoelectric element in a condition that it is closely kept into contact with a wall face of the intake system, and control the distorting motion of the piezoelectric element by a control means.

When the vibration is generated on a housing 1a of an air cleaner 1, the distortion of which the directions are periodically reversed, is generated on a piezoelectric element of a piezoelectric module 4 which is mounted in a condition that it is closely kept into contact with the inner and outer both faces of the housing 1a. Whereby a voltage signal which is periodically changed, is output from the piezoelectric element to be input to a control circuit. When the vibration of the housing 1a is started with the resonance frequency, a control circuit having the frequency characteristic corresponding to the resonance frequency, is made to act, so that the distortion of the piezoelectric element 5 is inhibited. That is, when the housing 1a is elastically deformed by the vibration, the compression stress is generated on the piezoelectric element of the piezoelectric module 4 on the tensile side, and the tensile stress is generated on the piezoelectric element of the piezoelectric module 4 on the compression side, whereby the deformation of the housing 1a is inhibited.