The McKinney-Anderson paper and its impact on sediment acoustics

Abstract

The earliest comprehensive, in-situ measurements of the acoustic backscattering strength of the seabed as a function of frequency, grazing angle and sediment type were made by McKinney and Anderson, and published in the society’s journal in 1964. It was a landmark paper and laid the groundwork for subsequent measurements and models. It is widely referenced in books and papers where seabed scattering and sonar performance prediction are concerned. Scattering strength and sediment classification, usually quantified in terms of the mean grain diameter, were thought to be closely connected. In the laboratory, using pristine samples of sorted sand, this connection was clearly demonstrated, but in situ it was overwhelmed by other factors, such as uneven size distributions, biological activity and roughness. The underlying nature of the seabed is also reflected in the scattering strength. For the same roughness, density and sound speed, the solid/fluid model consistently overestimates the scattering strength because it cannot account for the relative motion between grains and pore water. Thus, recent advances in poroelastic modeling can shed new light on the measurements of McKinney and Anderson. [Work supported by ONR, Ocean Acoustics Program.]