Sound propagation over ground: Analytical approximations and experimental results

Approximations of the sound field emitted by a point source in the presence of the ground have recently been developed 1]. In this paper, these analytical expressions, slightly improved for computation, are compared with an exact representation of the sound pressure and two kinds of experimental results. The approximations, easy to compute, provide a reasonable accuracy for predictions of the sound levels in the asymptotic and intermediate (preceding the asymptotic) regions. Furthermore, numerical techniques (an optimization method) are presented for obtaining the “best value” of the ground normal impedance, from data obtained in Kundt's tube and far field measurements.