Controlling sound absorption by an upstream resistive layer

Resistive screens, or perforated plates, are widely used upstream of porous materials. They can be used either for protection or decoration, or for acoustic properties enhancement. This study points out the role that a resistive layer can have upstream on a porous material. Based on numerical simulations, this work gives the guidelines for rational use of high resistive layers in order to maximize the normal sound absorption of porous multilayers. Two major results emerge: (i) the upstream resistive layer can control the sound absorption of the porous multilayer, while nullifying the acoustic properties of downstream layer and (ii) this upstream layer may be detrimental to sound absorption of porous multilayer. Experimental validation on a porous multilayer, controlled by a woven textile, supports these findings. The sound absorption of material with poor sound absorption performance can be enhanced with a conveniently designed resistive layer. (C) 2011 Elsevier Ltd. All rights reserved.