Sound waves of finite amplitude are subject to progressive distortion or change in form during propagation. Theoretical analysis of this phenomenon for a plane wave neglecting dissipative forces leads ultimately to a multiple valued solution for acoustic pressure, displacement, etc. This is inconsistent with fact. R. D. Fay, introducing viscosity into the analysis, arrived at a solution in which the progressive distortion is balanced by the dissipative effects of viscosity. This wave, called the “stable” form, is essentially sawtoothed, varyi...
