Abstract
It was investigated experimentally whether the sound decreasing effects of sound absorbing material structures on the sinusoidally vibrating rigid surface are obtained or not. In the experiment, the one-dimensional acoustic tube was used and its one end is excited by the sound absorbing material structure and the other end is closed by glass wool. The experiments showed that almost 70% sound pressure decreasing effect is obtained at the maximum in the frequency range of 1∼3 kHz for the hard porous or fiber aluminum sound absorbing materials with the back air space made by using honeycomb structures. And it is observed that the frequency dependency of this decreasing effects is qualitatively and almost quantitatively coincident with the square root of reflectivity of the stationary absorbing material structure. But, for the urethane foam, this tendency could not be observed. It is supposed to be the flexible vibrational characteristics of urethane foam.
