Experimental investigation of the effect of absorption material on the non-linear properties of perforated plates

Abstract

Combinations of perforated plate and porous material are used in numerous applications for noise reduction at high sound pressure level, such as in aircraft engines and automotive mufflers. Therefore, it is important to have a better understanding of the acoustic property of these systems. A semi-empirical model is a common way to calculate and understand the sound absorption of these systems. Previous studies show that the interface between a perforated plate and porous material have direct effect on the non-linear property of the perforated plate and sound absorption. Therefore, in this study two conditions of perforated plate and porous material combinations was considered. First, when the perforated plate has direct contact to the porous material and second, when there is air gap between them. Results of this research shows that the variation of non-linear acoustic resistance in case either with or without a cavity gap of air is relatively small.