The Biot theory is used to compute compressional wave speeds and attenuation in fluid–solid suspensions. The frame moduli are estimated from the self‐consistent theory of composites, assuming needle‐shaped pores and spherical or ellipsoidal grains of uniform size. The permeability is computed from the Kozeny–Carman equation. The attenuation data are matched by assuming that all losses are caused by viscous absorption in the fluid.For suspensions of kaolinite, polystyrene beads, and glass beads in various fluids, the Biot model agrees with experimental sound speed data at least as well as do other models. For aqueous suspensions of kaolinite, of attapulgite, and of hydrous aluminum silicate pigments, the Biot model generally is in better agreement with attenuation data than are other models.