Sound Propagation in a Shallow Water Region Overlying a Viscoelastic Halfspace

Sound propagation in shallow water is investigated using the Green´s function and normal mode expansion techniques. The ideal fluid is bounded above by a pressure-release condition and below by a viscoelastic solid. A depth-dependent sound velocity is considered in the fluid column. Numerical results are evaluated using a digit- al computer to perform the calculations determined by the theory. The input parameters are chosen from the conditions described at an experimental site in the Baltic Sea. The output is in the form of a plot of transmission loss versus horizontal source-receiver separation distance. The computer simulation agrees qualitatively with the experimental results and demonstrates the importance of the bottom boundary composition on the attenuation of the sound. The authors´ approach to the bottom boundary condition incorporates the concept of impedance and hence is very general in application.