The Propagation of Sound in an Inhomogeneous and Moving Medium I

In this paper the wave equations for the propagation of sound in an inhomogeneous and moving medium are established (Section I). In Section II special cases are considered and a generalization of Kirchhoff's theorem (Huygens' principle) is given for a moving medium. In Section III the general equations of acoustics are considered in the approximation of geometrical acoustics. And finally, in Section IV the equations are generalized for the case of a medium containing a salt solution (sea water).