Makarewicz [J. Acoust. Soc. Am. 82, 1706–1711 (1987)] has proposed an interesting method for predicting the attenuation of the A-weighted sound-pressure level at long ranges from a point source above a locally reacting plane ignoring the influence of meteorological and topographical conditions. An error found in his derivation resulting from inconsistent use of his chosen sign convention for the time dependence is documented. Furthermore, use of a more versatile ground impedance model, namely, a two-parameter variable porosity model, is suggested. This enables a closed-form solution for minimizing the A-weighted mean-square sound pressure.