  In this paper we revisit the classical sound dispersion and attenuation
theory due to Stokes [5], 1845, and Kirchhoff [3], 1868, for the propagation of
sound in non-ideal fluids. In particular we reformulate the analysis due to
Fletcher[2], 1974, showing conditions for which the sound propagates at the
isothermal speed of sound. Also we presents asymptotic developments making
precise the physical conditions under which the different dispersion and
attenuation formulas apply.The more complex case of two-fluid flow is addressed
by Benjelloun and Ghidaglia [1] to which the reader is referred.
