Porous Sound-Absorbing Materials Part I: Applications and Parameters

Sound absorbing porous materials have a wide range of applications in various acoustic designs. In this paper, by introducing different types of acoustic porous materials, various applications of these materials in other industries are discussed. Since the designer needs to be familiar with the parameters expressing the acoustical and mechanical properties of porous materials, the main parameters of these materials are bulk density, modulus of elasticity, flow resistivity, porosity, viscosity characteristic length, etc. are introduced. Then, different methods of direct measurement of the parameters of this type of material based on the international standards are described. At the end of the article, direct and indirect methods of measuring materials are mentioned. In the second part of this paper, the mechanisms of sound absorption in porous materials, the existing experimental modeling and theory for porous materials, methods for measuring acoustic absorption coefficient, and current and future research subjects in this field are described.