Diffraction of sound due to moving sources by barriers and ground discontinuities

Abstract

The solution for diffraction of sound by a wedge is extended to sources in uniform motion parallel to the obstacle. By means of an auxiliary transformation the problem is reduced to that of a set of stationary sources so that the resulting solution is in accordance with well-known models. Applications to prediction and abatement of transportation noise are considered. The formulation for the diffracted wave is combined with the solution for ground reflection of sound due to moving sources. New models for the sound field due to a source in motion along a barrier above the ground and for a source moving parallel to an impedance discontinuity are derived. In both situations, greater sensitivity to motion of the resulting sound pressure levels is found on source approach. However, attenuation of sound from moving sources by barriers is found to be so little affected by motion that design schemes for stationary source are relevant. On the other hand, it is noted that noise predictions must account for source motion.