Strength and wave parameters for sound propagation in random media.

Abstract

Line-of-sight sound propagation of plane and spherical waves in a statistically isotropic, random moving medium is considered. The variances of the phase and log-amplitude fluctuations of these waves are expressed in terms of the strength and wave parameters for arbitrary spectra of temperature and velocity fluctuations, and results are then derived specifically for the Gaussian and generalized von Kármán spectra. This representation of the variances reduces significantly the number of independent parameters of the problem and enables better understanding of sound scattering by plane and spherical waves, and due to temperature and velocity fluctuations. Using this representation, the boundary between the weak and strong scattering regimes is determined in terms of the strength and wave parameters. The results obtained are compared with the Λ - Φ diagram adopted in ocean acoustics. Other statistical moments of plane and spherical waves in a medium with arbitrary spectra of temperature and velocity fluctuations such as the mean sound field, the spatial and temporal mutual coherence functions, the coherence bandwidth, and the variance of the angle-of-arrival fluctuations are expressed in terms of the strength parameter and length scale of the fluctuations.