Sound fluctuations due to soliton-like internal waves crossing shallow water acoustic trace

The subject of the paper is natural internal waves packets (IWP) influence on low-frequency sound in shallow water (ocean shelves). We consider two distinct case: IW propagation approximately along and across acoustic trace. In the first case the coupling modes method is used to consider sound scattering due to WP. Sound scattering leads to two processes: redistribution of full sound intensity both between modes and between coherent and noncoherent (fluctuating) components. Sound scattering by IWP can be reason of a both additional (resonance) sound absorption by bottom and increasing of sound fluctuations. In the second case horizontal refraction of sound waves is considered. The possibility of existence of `horizontal waveguide' is estimated.