Two dimensional sound propagation over a ridge

The sound propagation over an arbitrarily-shaped ridge situated on an infinite plane is treated using the Boundary Element Method, for which the Helmholtz integral equation in two-dimensional half space is formulated. A previously developed computational scheme for the acoustic problem at wave length shorther than the characteristic dimension of the radiator or scatterer is applied to the propagation of relatively low frequency sound over large terrain features. The numerical results using the Boundary Element Method are compared to those using algorithms for the Matched Asymptotic Expansion technique.