Acoustic properties of a stretched membrane with a sound absorbing backing

Abstract

The normal sound absorption properties of a composite acoustic material consisting of a plastic membrane stretched to uniform tension and located in front of a fiberglass blanket were investigated. Performance of the composite material was evaluated both theoretically and experimentally. Very low sound absorption was exhibited by the composite material at frequencies of membrane antiresonance. However, at frequencies between membrane antiresonances the material displayed acceptable sound absorption characteristics. Choice of membrane radius and tension permitted frequencies of antiresonance, and, thus, of low absorption, to be specified. Membrane density, membrane thickness, and the distance from the absorber to the membrane were shown to be controling factors in acoustic absorption at frequencies between membrane antiresonances.