High frequency backscattering from sandy sediments: Single or multiple scattering

Abstract

As the sand grain size approaches the acoustic wavelength, the underwater backscattering strength increases. Laboratory measurements show that the shallow-grazing angle backscattering strengt increases as the third power of the normalized grain diameter, until it reaches a saturation level. In this regime, it has been shown that th e attenuation of the sound in the sand increases as the fourth power of frequency and the speed of sound decreases with increasing frequency. The most likely explanation for the attenuation and speed dispersion is multiple scattering [Schwartz and Plona, Journal of Applied Physics, vol. 55, 1984, and Kimura, J. Acoust. Soc. Am. EL, vol. 129, 2011]. The multiple scattering model is applied to the backscattering process, and it is shown to be consistent with the published backscattering data. © 2013 Acoustical Society of America.