DIRECTIONAL SPECTRAL SPREADING IN RANDOMLY INHOMOGENEOUS-MEDIA

The redirection of the energy flux in an acoustic signal due to random volume scatter can be described by a radiative transport theory. We consider and compare three such theories, differing one from another in the form of the beam pattern of the incrementally scattered energy, sometimes referred to as an effective scattering cross section. Two of the three theories (termed here quasi-isotropic and highly anisotropic) have already received some attention in the acoustics literature. The third (termed here exact) contains the other two as limiting approximations. The comparison is both analytical and numerical; the numerical phase accomplished for an illustrative acoustic experiment carried out in a canonical environment. The results emphasize the importance of the high anisotropy of the sound-speed fluctuations caused by internal waves on the redirection of energy flux measured in a vertical plane. © 1979, Acoustical Society of America. All rights reserved.