An Engineering Model for Sound Pressure in Shadow Zones Based on Numerical Simulations

A model is introduced to calculate the sound in meteorologically generated shadow zones. The method uses raytracing to determine the border of the shadow zone. An empirical formula was defined which uses the relative position of the receiver in respect to this border to calculate a spectral meteorological access attenuation. The model was derived from reference data using a simulation based on wave theory, where sound propagation was calculated applying the finite difference time domain (FDTD) method. In the proposed empirical model, the influence of refraction upon ground effect is not explicitly taken into account. Therefore, the behaviour of the ground effect was investigated using further numerical simulations.