Measurement and analysis of broadband acoustic propagation in very shallow water

The results of an experiment conducted to understand the frequency dependence of acoustic propagation in very shallow water using a ship as an acoustic source are presented and the possible causes of the features appearing in the results are discussed. The result shows large propagation losses at a frequency of approximately 140 Hz. The results of numerical simulation including the shear property and layered structure of the bottom imply that the features might be caused by the shear property of the lower sediment that lies below the thin upper fluid sediment.