ABSTRACT
A simplified Biot model can be used to evaluate reflection and transmission of sound waves on highly porous sound absorbing materials like plastic foams or mineral wools. Since the fluid saturating these materials is air, the large density difference with the frame will result in a partial decoupling of the two Biot waves. The energy transported by each of these waves depends on the material parameters and the edge conditions. In the case of open surface structure, the air-borne wave is generated most efficiently, whereas in the case of sealed surface structure, the frame-borne wave is generated. A case is presented where both waves can be observed simultaneously.
