Acoustics of Mud Layers at the Bottom of Coastal Waters

The acoustic properties of mud as which occurs at the bottom of the ocean in coastal regions are discussed from a fundamental viewpoint. The definition of mud is taken as an unconsolidated sediment of clay and/or silt, together with material of other dimensions (such as sand), mixed with water, without connotation as to composition. It is contended that mud is distinguished from sandy sediments in that the particles in the mud, which are substantially smaller, are not in close contact with each other. Because of this, the commonly used Biot model for a porous medium is inapplicable.