Development and validation of a model predicting the performance of hard or absorbent parallel noise barriers

This paper deals with the development and the validation of a model used to evaluate the performance of parallel noise barrier configuration. These barriers are generally used to reduce the noise emitted by traffic roads. The formulation and algorithm used combine the multiple reflections occuring between the parallel barriers by the acoustical imagery method, and the barriers absorption by the modified Delany-Bazley impedance model. They also take into account parallel barriers with different heights, the ground effect, and a spectral sound power for various type of traffic noise. A complex summation between acoustical waves originating from a single source is used to obtain rigorously constructive and destructive acoustical interferences. This approach has been validated against systematic experimentations in controlled conditions in a semi-anechoic room. A case study is also presented which highlights the importance of applying absorbent materials on the barriers in terms of an increase in efficiency.