On the acoustic transparency of perforated metal plates facing a porous fibrous material

Abstract Thin impervious layers, cloths or perforated plates are usually utilized with fibrous absorbing materials in order to avoid small particles, coming from deterioration over time flow abrasive effect, becoming dislodged and polluting the environment. These protective facings be carefully considered analyzed, since they can affect acoustical behavior of “backing” material. This study addresses this issue through an experimental survey a theoretical analysis using Transfer Matrix Method (TMM). Experiments have been performed frequency range 160–2,500 Hz, analyzing different behaviors due multiple combinations percentage open area air gap between facing Experimental data shown marked effect perforation, at least up threshold value 20%, whereas slightly affected acoustic covered The TMM was applied tested faced system, results were compared, showing good accuracy model. Several geometrical configurations then modeled possibility method assess transparency metal assessed.