QLAN Zuwen 

(Laboratory of Medical Acoustics ,Institute of Acoustics ,Chinese Academy of Sciences Beijing 100190) 

Received May 14, 2008 

Abstract Based on the author,s theory for acoustic propagation in granular media and by employing the extinction theorem, the sound speed formulae in these media were derived. The numerical computations of sound speed in marine sediments and air-filled sand were carried out , and the results demonstrated that under the normal atmosphere the sound speed in air-filled sand is lower than the sound speed in the air . The numerical results also indicated that the influence of scattering interaction between the grains upon the sound speed in the marine shallow-layer sandy sediments has to be taken into account; however, the influence of the viscous-wave interaction can be neglected. The theoretical results obtained from the rigid-granular model seem to match the measured data better than from the elastic-granular model, even the latter model fits better for the real situation, indicating further measurements are necessary in order to gain an insight into this problem thoroughly. Through an analysis of experimental data published in journals a conclusion can be drawn that the theory of granular media is suited to deal with the problems of the sound propagation in air-filled sand better than the theory of porous media.

PACS numbers: 43.30, 43.20