A general theory is presented to derive the coarse-grained equations governing the macroscopic behaviour of sound-wave propagation in suspensions from the standpoint of statistical continuum mechanics. The expressions for effective physical properties are obtained. The resulting general expression for the effective sound-wave velocity is applied to acoustic wave propagations in bubbly fluid. It is shown that the result for the sound-wave velocity agrees well with experiment. It is found that the basic equation for wave propagation in continuous random media does not apply to wave propagation in discrete random media (or suspensions). The expressions for the effective viscosity and thermal conductivity agree with those for the effective viscosity and thermal conductivity in a dilute suspension in the dilute limit and are applied to more concentrated suspensions.