Influence of surface shape and perforation of plastics on sound absorption

Abstract

The aim of the paper is to study the effect of the surface shape and perforation of plastics on sound absorption. Samples with different asperity heights, depths and numbers of holes were prepared by means of CNC milling machine. Experimental measurements of frequency dependencies of the sound absorption coefficient were realized by the transfer function method using Kundt́s impedance tube at normal incidence of acoustic wave on the investigated materials. The study was performed on two types of polyurethanes. Different factors, that have influence on sound absorption, are evaluated in the conclusion of this work. Both investigated materials are also compared in terms of their ability to absorb sound. © (2014) Trans Tech Publications, Switzerland.