The Transmission of Sound through a Stochastic Interface.
PENNSYLVANIA STATE UNIV UNIVERSITY PARK ORDNANCE RESEARCH LAB
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The problem of sound transmission through a stochastic interface was investigated using a surface model which employed two scales of roughness. The theory was developed for application to the problem of sound transmission from air to water at the ocean surface. A perturbation method was applied to obtain the local surface values of the pressure and the normal derivative of the pressure at the stochastic interface for use in the Kirchhoff integral. Two different correlation function models were employed, one corresponding to isotropic surface roughness, with the other corresponding to anisotropic surface roughness. The isotropic model revealed the general behavior of the effect of the large scale roughness on the mean square pressure as a function of position and frequency but failed to indicate the effect of the small scale roughenss. In addition, the effect of change in wind speed was not observed. The anisotropic model a similar general behavior for the effect of the large scale roughness and, in addition, indicated the effect of the small scale roughness and the variation with change in wind speed. Author Modified Abstract