Diffraction near a porous half plane

The diffraction of a spherical acoustic wave by a porous half plane is considered. An approximate boundary condition, depending upon the thickness and material properties of the half plane, is obtained. The mathematical problem corresponds to an approximate model for a noise barrier which is not perfectly rigid and transmits sound. The principal purpose of the barrier is to reduce the transmitted sound, so the flow resistance of the pores is large. This consideration is important in the sense that point sources are regarded as reasonable substitutes for real sources. Expressions for the total far field for the leading edge (no wake present) and the trailing edge (wake present) situations are given.