Practical Description of Diffraction at Wedges Applied to Propagation Model in a Built-Up Area

In a propagation model of the environmental noise model for a built-up area, wave multiple interactions are presented as chains of elementary interactions. The chain can contain sequences of reflections and transmissions and diffraction, which can be of any arbitrary order (higher than one) and can appear at any place in a chain. The procedure developed for diffraction description is the one appropriate to be applied in the propagation model. The diffraction description assumes validation of high frequency approximation and the thick boundary for the region in the vicinity of boundaries of shadows where the sound pressure is assumed to be equal to its value exactly at the boundary. The reflection properties of a diffraction wedge are included into the description of diffraction process. The comparison between results of the exact solution and the experiment has shown better agreement than expected. Enough good agreement is observed up to a source and observation point distances from a wedge of a wavelength order.