On a modification of the wave equation for a layered medium

A new form of the wave equation in inhomogeneous media is presented which does not contain derivatives of the medium parameters in its coefficients. Hence this equation can be used not only for the case of smooth but also for the case of abrupt changes of the parameters with the coordinates. The equation can be used for waves of different nature.

To illustrate the advantages of the new form of the wave equation four problems have been solved. They are: scattering of a plane sound wave by weak inhomogeneities; excitation of a lateral wave; the symmetry of the plane-wave transmission coefficient with respect to inversion of the path of the wave; and plane were reflection from a thin inhomogeneous layer.