An improved ray-tracing algorithm for predicting sound propagation outdoors

Abstract

A new ray-tracing method for predicting the sound field near a flat impedance ground in a refracting atmosphere is developed that includes the effect of vector wind and turbulence explicitly. Improvements on previous ray-tracing schemes include the use of a generalized Snell’s law, an integration by means of a Gaussian quadrature, and a bracketing method for finding the ray paths. For the turbulence calculations, the interray coherence is determined from turning point heights rather than from integrals along the ray paths. A more efficient algorithm is developed for computing the sound field above an impedance plane in a realistic atmosphere. Despite the inherent limitations of the ray-trace approach, particularly in respect of logarithmic wind profiles, the algorithm is valid over a wide range of practical situations.