Point Source Scattering in a Porous Barrier

The diffraction of a spherical acoustic wave by a half plane in an infinite plane, porous barrier is considered. The barrier is modeled as a rigid material filled with narrow pores, more or less normal to the plane, that provide sound damping. However, the compressibility of the gas in the pores is also considered so that some sound transmission takes place. An approximate boundary condition is derived that models both these effects. The principal purpose of the barrier is to reduce the transmitted sound so that the flow resistance of the pores is large. This consideration is important in the sense that point sources are also regarded as reasonable substitutes for real sources. The far field is calculated using integral transforms, the Wiener-Hopf technique and asymptotic methods.