How the structure of a medium is seen by an acoustic wave*

Division of heterogeneous media into three types, depending on the dimen¬sions of heterogeneities. Media with macroheterogeneities occurring naturally and in technological materials. Chraracterization of microheterogeneities. Fre¬quency and energy transport ranges requiring quantum representation of waves in media with heterogeneities caused by crystal structure defects. Quantum phenomena and background noise for audible sounds. Density of phonons occur¬ring in acoustic impulses. Quantum phenomena possible in biological substances.