Slow wave in a two-layer acoustic wave guide, placed in an elastic medium

Kinematic characteristics of a slow wave, propagating in acoustic medium consisting of a two layer (water-oil, gas-oil), and locating inside elastic medium are considered. It is shown that the slow wave appear for arbitrary parameters of model. Its velocty in the low-frequency approx-imation depend on the gas and liquid densities and do not depend on the velocities in its. Dispersion curves of phase velocity of wave are constructed for the wide band of frequencies.