TRAFFIC NOISE IN URBAN AREAS

Although environmental factors are known to play an important part in controlling urban noise levels, the exact effects of processes such as scattering and absorption, and their complex interactions, are not well understood. Most research has concentrated on problems involving propagation in only one or two well defined streets. In these cases, the problem of describing sound propagation may be studied usng discrete image-source techniques. However, over larger distances, the number of image sources necessary to describe multiple reflections of sound from even a single source becomes very large. In these circumstances, it would seem reasonable to adopt a statistical treatment of the problem. In this paper, propagation over large distances from a dense traffic noise source is considered, and is described by a random walk model. The resulting expression for sound level arising from road traffic is given preliminary verification by comparing its predictions with the results of a traffic noise survey conducted in Copenhagen. The level of agreement between predicted and measured sound levels suggests that this approach may be useful in describing urban sound propagation on a large scale. (Author/TRRL)