SOUND-PROPAGATION FROM A POINT-SOURCE OVER EXTENDED-REACTION GROUND

Through comparisons with numerical predictions, with data from laborat ory experiments and with outdoor data obtained over snow, heuristic mo difications of the classical analytical approximation for the field du e to a point source above an impedance plane are shown to be adequate for predicting sound propagation from a point source close to layered porous media with extended reaction. The main deficiencies are for ext remely low flow resistivities and at close ranges. It is shown that mu ltiple layering offers a possible explanation for previously reported difficulties in obtaining theoretical fits to propagation data over sn ow [J. Acoust. Soc. Am; 77, 67-73(1985)]. (C) 1998 Acoustical Society of America. [S0001-4966(98)00808-X]