Nonlinear sound in a gas-saturated sediment layer.

Wave propagation in a near-bottom layer containing gas bubbles is analyzed. Evolution equations are derived for intense acoustic waves and wave beams in a medium with an inhomogeneous bubble distribution. The field of an intense beam along the axis of the focusing sound channel is calculated. The coefficients of reflection and passage of sound from a homogeneous medium into a bubble layer and back again are calculated. It is shown that the near-bottom layer can effectively trap rays incident on it and ensure a waveguide propagation character. The presence of bubbles increases both the interval of angles at which the wave penetrates the layer and the interval of angles at which rays undergo total internal reflection and do not depart the layer. The acoustic field in the layer from a point source is calculated. [ABSTRACT FROM AUTHOR]