Acoustic Propagation and Scattering within Sand Sediments: Laboratory Experiments, modeling based on porous media theory, and comparisons to SAX99 results

As part of the Sediment Acoustics Experiment 1999 (SAX99) several researchers measured sound speed and attenuation. Those sound speed and attenuation results have been compared to the frequency dependence predicted by Biot theory. The comparisons indicate that the variation of sound speed with frequency is well modeled by Biot theory as frequency increases, but the variation of attenuation with frequency deviates from Biot theory as frequency increases [1]. Examination of received waveforms has lead to the hypothesis that this deviation is due to increased scattering a high frequencies that is not accounted for in the present version of Biot theory. The objective of the present work is to determine whether the discrepancy between the measured attenuation and that predicted by Biot theory can be explained by the presence of scatterers or whether a theory which accounts for the unconsolidated nature of the sediment such as that suggested by Buckingham[2] is necessary to properly model the sound propagation.