The propagation of a scattered acoustic boundary wave over a rough wedge.

Abstract

The theory for the generation of a scattered acoustic boundary wave over a slightly rough planar surface has been developed by I. Tolstoy [J. Acoust. Soc. Am., _66_ 1135-1144 (1979)] and experimentally verified by Medwin et al., [J. Acoust. Soc. Am., 6_6 1131-1134 (1979)]. In the present experiment the propagation of the boundary wave over a wedge is studied. It is found that the boundary wave and the geometrically spreading volume wave diffract from the crest in the same manner. The amplitude ratio of the boundary wave to the diffracted volume wave, where the growth of the boundary wave from the crest is due to a phased line source at the crest caused by the diffracting volume wave, was found to have an average frequency dependence, f², and an average range dependence, R⁺⁰˙⁵. The amplitude ratio of boundary wave to diffracted volume wave due to propagation over the rough wedge gave an average frequency dependence of f² and an average range dependence of R⁰˙³. Low wave number grazing propagation over a wedge produces a boundary wave whose amplitude can be many times that of a diffracted volume wave for a smooth surfaced wedge.