Sound fields inside street canyons with inclined flanking building façades

Abstract

Street canyons are common in modern cities. It is well known that the multiple sound reflections within the canyons tend to increase the noise levels inside the canyons. An scaled down model experiment was conducted in the present investigation to study the effect of the inclination of building façade on the sound field. A line source consisted of 100 2-inch aperture loudspeakers were used to simulate the road traffic source. The whole experiment was carried out inside an anechoic chamber. The canyon was 4m long, 2m high and 1m wide (1:4 scale down ratio). The case of a single façade was used acted as the reference. The reverberation inside the model canyon was strong when the two model façades are vertical (inclination 90 deg) and parallel to each other. However, it was found that such reverberation deteriorated very rapidly as the inclination of one of the model façade was reduced to 80 deg. The sound strength inside the model canyon was also reduced. The sound levels at the top region of the canyon decreased more rapidly. It was also found that the effect of the opposite façade was basically unchanged once its inclination was less than 60 deg.