Sound propagation in a semi-infinite liquid overlying a homogeneous viscoelastic halfspace

Approximate results are obtained for the acoustic response due to a steady-state point source in a semi-infinite liquid overlying a viscoelastic halfspace. The study is intended for application to the acoustic classification of sediments on the continental shelf. The response in the acoustic field is formulated as a Green´s function expressed in an integral form. The integral is evaluated approximately for two cases corresponding to two types of experiment: one for nearbottom testing, and the other for oblique-incidence testing in the radiation zone. Evaluation of the integral yields various expressions, each representing the leading term in an asymptotic expansion. The terms are interpreted physically as reflected, lateral (refracted) and surface waves. The types of response for both cases are discussed and compared with previous results.