title: Propagation of elastic waves in granular solid hydrodynamics.
abstract: The anisotropic stress-dependent velocity of elastic waves in glass beads--as observed by Khidas and Jia [Phys. Rev. E 81, 021303 (2010)]--is shown to be well accounted for by "granular solid hydrodynamics," a broad-range macroscopic theory of granular behavior. As the theory makes no reference to fabric anisotropy, the influence of which on sound is in doubt.
authors.affiliation: Institut für Theoretische Physik, Universität Tübingen, 72076 Tübingen, Germany, EU.
authors.forename: Michael
authors.initials: M
authors.lastname: Mayer
authors.forename: Mario
authors.initials: M
authors.lastname: Liu