A simple model for the acoustic cross section of sand grains

Previous work on determining the acoustic cross section of sand grains [Geophys. Res. Lett. 9(2), 175–178 (1982)] identified a problem with the application of the simple compressible sphere model for the cross section. Use of the complete elastic sphere model [J. Acoust. Soc. Am. 34, 1582–1592 (1962)] failed to remove the conflict with observation. Application of the bistatic cross-section theorem to the angle averaged cross section shows that the appropriate cross section is the total absorption cross section, not the backscatter cross section. The total absorption cross section for the fluid sphere model is found to be in semiquantitative agreement with scattering data for sand grains.