Approximate solutions to the wave equation for a medium with one discontinuity

This thesis deals with a particle limit for the n dimensional wave equation and shows that there are asymptotic solutions for certain pulses in the high-frequency limit. These pulses are shown to propagate along rays predicted by geometrical optics. The solutions are computed up to an error which approaches zero as the pulse approaches the particle limit. The method gives a closed solution to the question of where the energy propagates. We assume that the n dimensional space is divided into two halfspaces with two different wave speeds and that these two halfspaces have an interface where the wave speed is not continuous.