Sound propagation in air-saturated random packings of beads

In the pore space of packed grain material, transport properties are characterized by macroscopic parameters. Some of them, tortuosity, characteristic dimensions, viscous permeability, and trapping constant, are measured for a random packing of glass beads and compared to evaluations performed in previous studies. These parameters are used to predict the surface impedance at normal incidence of a layer of glass beads. The predictions are compared to measurements performed at normal incidence in a Kundt tube. (C) 1998 Acoustical Society. of America. [S0001-4966(98)04610-4]