Signal Variation in a Random Medium.

An acoustic ray-wave synthesis was developed by combining the wave theory methods of Kirchoff and Helmholtz with the ray theory methods of Sommerfeld and Runge. The result is a generalization of the Kirchoff-Helmholtz integral formulation of the wave equation in which the kernels are ray theory expressions and in which an additional term appears. The ray theory kernels represent the gross properties of the fields, while the extra term represents scattering by the medium and is the additional field required for an exact solution. The acoustic ray-wave synthesis was applied to the problem of signal variation in a random medium. The problem is found to separate naturally into three regions which are designated near field, intermediate field, and far field. The expressions for the coefficient of signal variation in the three regions define a function of range and frequency and plots of this function are compared to the results of various experiments.