Acoustic waves at the interface of a gaseous and dusty media

The effect of a dusty gas on the reflection and refraction of acoustic waves at the interface with a gaseous medium of different density and sound speed is analysed. It has been found that the nonequilibrium effects of gas-particle interactions give rise to modified laws of refraction. The reflection and transmission coefficients are modified versions of the results for single-phase media. The reflected wave can be amplified if the shear flow speed exceeds the phase speed of the incident wave. Detailed comments have been made on the effects of the parameters of the twin media on the directions of propagation and amplitude relations.