Investigation of the sound distribution in street canyons with non-parallel building Façades

Abstract

Sound propagation in street canyons have been a topic of interest for decades. In a congested city such as Hong Kong, street canyons with large height to width ratios are a common sight. Many prediction models have been developed over the years, but the problem is still of interest because of the complexity due to the multiple reflections and varying surface conditions in real life cases. In this paper, a 1:4 scale model experiment of a street canyon, 4 m long and 2 m high, is presented where one of the facades is inclined. The reference case is with two parallel facades, which is compared with cases when one facade is tilted 80°, 70°, and 60°. The measurements were conducted in an anechoic chamber and a line source array generating white noise was used for simulating traffic noise. The sound distribution patterns were studied on the reference wall and the inclined wall. It was observed that the sound strength and the reverberation decrease rapidly when inclining the opposite wall. For low and mid frequencies, the sound reduction was more significant closer to the top of the inclined facade, while the opposite could be seen for the vertical facade.