The propagation of audible sound through air‐water fogs is studied theoretically using a generalized Burgers’ equation applicable to media exhibiting relaxational as well as classical thermoviscous absorption. The effects of vibrational and rotational relaxation of the gas molecules, and of polydisperse water droplet relaxation due to mass, momentum, and heat exchange with the gas are included in the formulation. Analytic expressions showing the dependence of dispersion and attenuation parameters on gas and droplet properties and on sound frequency are derived. Agreement between theoretical predictions and available experimental measurements is good. The results clarify those conditions under which sound propagation in fogs is significantly different from propagation through humid air containing no suspended droplets.