The Examination of the Upper Layers of the Seabed by the Means of the Acoustic Methods

Propagation of acoustic waves in the sea, in particular in shallow sea, depends on several factors. The basic of them are source power and frequency of acoustic waves, spatial distribution inhomogeneous medium in which acoustic wave propagates, and distributions of speed of sound and density of seawater. The coastal conditions, which limit water medium from above (free surface of the sea) and from bottom (the seabed), are no less important. In this paper we will consider the examination of the layer structure of the seabed by the means of the acoustic methods. By the notion of acoustic methods we mean use of phenomena in the field of nonlinear hydroacoustics. Based on this, the parametric sonar was constructed and was used to the seabed sounding. This parametric sonar is commonly called sub-bottom profiler. The selected results of extensive experimental research, that have been performed in waters of the Gulf of Gdańsk in the years 2008-2010, will be presented in this work.