ACOUSTIC PROPERTIES OF AN INFINITE ELASTIC PLATE WITH A BACK CAVITY

The reflected sound field from an infinite elastic plate with an air back cavity is theoretically analyzed to clarify the effect of the back cavity on the reflectivity of the plate. The theory is verified by comparing the theoretical results with the existing measured data obtained in a reverberation room for the sound absorption coefficient of panel absorbers. Furthermore, the mechanism of the sound absorption by the panel absorbers is discussed in the light of the calculated results, which shows that the sound absorbing power existing in the back cavity has a significant effect on the sound absorption by the panels. The effects of the parameters relating to the sound reflecting system are also discussed with some numerical examples. The reflectivity of the plate with the air back cavity has a significant dip around the coincidence frequency in all cases, and at low frequencies in some cases.