The generalized inhomogeneous wave equation that governs magnetoacoustic, vortical and thermal motions in compressible fluids and that thus is applicable to the problem of the heating of the solar chromosphere and corona is obtained. The effects of kinematic and bulk viscosity, heat conduction, Joule dissipation and magnetic diffusivity are included. Under the usual assumptions, the generalized wave equation reduces to the well-known equations of Lighthill, Kulsrud, Phillips and others. The major problems encountered in applying Lighthill's mechanism to sound generation in turbulent media are reviewed for both the subsonic and supersonic cases.