A simple method for accurate prediction of finite barrier insertion loss

A simple model of diffraction is developed that can predict accurately the insertion loss of finite length barriers. The model is based on the geometric theory of minimum diffracted paths. Assumptions are made on the phase and amplitude of each diffracted wave to obtain a new and rather simple formulation of the solution. It provides a clear picture of the sound attenuation performance of a barrier as a function of barrier length. Extensive model experiments are used to verify the model. The model’s accuracy in predicting the overall pattern of the narrow-band insertion loss is found to be comparable to that of an integral equation method, although the latter method produces better prediction in the fine details of the sound field. The model is much simpler than and as accurate as other methods that apply the usual geometric solutions to each diffracted path, and represents a major improvement on Maekawa’s energy summation method for octave band finite barrier calculations.