Assessment of adequacy of ray acoustics approach for prediction of barrier insertion loss in the presence of a reflecting ground

Abstract

The precision of insertion loss prediction obtained by applying Kurze–Anderson formula to each of the four possible ray paths connecting source and observer in the presence of a reflecting ground, and computing interference appropriately, is discussed. To this end, the field behind the barrier, given by the method described, is compared to that obtained by solving numerically the continuity and momentum equations simultaneously, using the appropriate boundary conditions to account for the perfectly reflecting ground and the barrier. Analysis of the agreement of the interference patterns obtained in both cases, for pure tones and for octave bands, permits determining the range in which the much simpler ray method provides sufficient results. Calculations with the Kurze–Anderson formula are performed with Mathematica 4.0, while the numerical propagation code is written in Fortran.