DETERMINATION OF THE ACOUSTIC PROFILES OF A SEABED IN SHALLOW-WATER USING THE OBSERVED CHANNEL FIELD WITH A GIVEN SOURCE

The acoustical characterization of the seabed in shallow water is aime d at. The seabed is modeled as follows: a homogeneous fluid layer (wat er) lying on a inhomogeneous fluid layer (sediment) above a homogeneou s fluid half-space (subbottom). Acoustical parameters (compressional w ave velocity, density) depend on the depth only. A cylindrical source and horizontal ligne of receivers are placed in the water. The data ar e the pressure field amplitude and phase on the hydrophone at several frequencies (from a few Hz to one kHz). The Green function of the stra tified medium can be obtained by Fourier transform of the field. From the result at low wavenumbers, the plane wave reflection coefficient o f the seabed is reconstructed at several frequencies and precritical a ngles. It can then be used as data in inversion algorithms retrieving the seabed parameters.