Performance of noise barriers with random edge profiles

Abstract

A noise barrier prevents sound from reaching a listener by the direct propagation path. However, sound still gets to the listener by scattering from the top edge that is called diffraction. It is well known that the diffraction edge behaves like a virtual source to the diffracted field. For a traditional straight edge barrier, the phase of the source along the edge is coherent. However, it will be random and less coherent when a random edge profile is present on a barrier. In this paper, a numerical method based on the diffraction integration of Rubinowicz for simulating the performance of random edge barriers is proposed. Comparisons of the performance of the straight edge barrier and random edge barriers with different profiles are presented. The results show that random edge barriers can produce significantly more insertion loss than the straight edge barrier, especially at high frequency. Moreover, a better efficiency of noise reduction can be obtained with increased jaggedness of the edge. Contour maps showing the effect of the barrier at different receiving points are also presented. © 2001 Elsevier Science Ltd.