Effect of macroscopic parameters on sound absorption and sound transmission loss of porous materials.

Abstract

Sound absorbing materials are indispensable nowadays for noise control applications. The acoustical behavior of these acoustic materials is governed by five physical (e.g., porosity, flow resistivity, tortuosity, viscous characteristic length, and thermal characteristic length) as well as three mechanical parameters (e.g., Young’s modulus, Poisson ratio, and loss factor). The characterization of these porous materials is very crucial as it plays a crucial role in design and development stage itself for predicting acoustic behavior of multilayer porous materials for higher sound absorption and transmission loss. This prediction depends on measurement accuracy of macroscopic physical parameters which are very difficult to measure except porosity and flow resistivity, which is the only standardized test until today; also availability of such rigs is also a problem for manufactures as they are available only at specialized test laboratories. This paper presents effect all of these parameters on sound absorption coefficient and transmission loss of the porous materials using Johnson–Champoux–Allard and Biot model for poroelastic materials. It also discusses results of simulation with effect of each parameter on acoustic behavior of the sound absorbing materials.