Abstract
In this paper, we apply the multi-scale analysis developed by one of the author and predict sound absorption coefficients for normal incidence from the microscopic structures. Poroelastic sound absorbing media are generally classified into foam material and fibrous material. Here we capture the characteristics of micro structure of polyurethane foam and fibrous felt from the observation by SEM such as the pore size, thin membranes of polygonal faces and fiber diameter, and construct unit cell models assuming that sound absorbing materials have a geometric periodicity in microscopic point of view. We obtained practically good agreements between measured and calculated sound absorption coefficients.
