Experimental Research on the Normal Absorption Coefficient of the Multilayer Material

Abstract

The normal absorption coefficient of the multilayer material was studied in this research. A measurement duct system was established at first, and then the absorption coefficients of multilayer material with different structures were measured through this experimental system. Some conclusions could be drawn: Compared with the uniform material, the multiple layer material can change the absorption coefficient significantly without increasing the thickness of the material in low frequency band. The position and the area density of the aluminum plate can both change the absorption coefficient significantly. The frequency corresponding to the absorbing peak value decreases with the increasing of the area density of aluminum plate. The absorption coefficient becomes larger near to one in low frequency band and in the meantime changes lower than 0.1 in the high frequency band. The position and area density of the aluminum plate can be designed to satisfy the requirements of the sound absorption.