Considerations on the sound absorption of non locally reacting porous layers

The sound absorption coefficient describes the ability of a porous material to absorb energy. It depends on the intrinsic acoustic properties of the porous material and is sensitive to the type of the wave-front impinging on the porous layer. From the total sound pressure field on the porous material, it is possible to obtain the sound absorption coefficient by separating the incident sound pressure field from the reflected one at the air/porous layer interface. The purpose of this work is to compare the ability of current analytical models to estimate the sound absorption coefficient of porous layers and others acoustical properties such as surface acoustic impedance and reflection coefficient, by using Finite Element Method (FEM) simulations as reference. This study also shows how the sound absorption coefficient of the porous layer varies when a spherical wave-front impinges on its surface.