Abstract
Street canyons are basic components of modern cities. Sound propagation in streets has been proven to be significantly affected by reflections from building façades. In this paper, an iterative model combining acoustic radiosity and the image source method (IMCRI) is proposed to investigate the effect of diffuse reflections on sound propagation in urban street canyons. By applying image patches, this model calculates both specular reflected components and diffuse reflected components in every reflection. The accuracy of this model is then validated with full-scale measured data from five actual streets with different scattering conditions. Good agreements of sound pressure level and reverberation time are found between the IMCRI and the measurements. The performance of the IMCRI is found to be superior to those of the existing energy models, especially for the reverberation time simulation.
Highlights
Noise is one of the problems that has arisen in modern cities and has been shown to have a significant influence on people’s life quality, such as speech interference [1], annoyance [2,3], sleep disturbance [4] and further health effects [5,6,7]
Various calculation models have been used to investigate the influential factors of noise propagation in urban streets, which can be classified into three groups: wave-based models [11,12], diffusion equation models [13], and geometrical acoustic (GA) models [14,15]
Models have been widely applied to investigate the fundamental principles of sound propagation in streets, including the image source model (ISM) [16], ray tracing model (RTM) [17], acoustic radiosity model (ARM) [18] and hybrid models based on these models [19,20]
Summary
Noise is one of the problems that has arisen in modern cities and has been shown to have a significant influence on people’s life quality, such as speech interference [1], annoyance [2,3], sleep disturbance [4] and further health effects [5,6,7]. As suggested by Ismail, this scheme could lead to considerable errors with the increase of the scattering coefficient and reflection order, especially for acoustic parameters determined by high-order reflections [26] Another key problem is model validation, especially in actual street canyons. Model validation can only prove that the measured data is in the range of the simulation result instead of analyzing the detailed accuracy of the calculation model This leads to difficulties in applying the model in actual street canyons with many surface conditions. Measurements in five actual streets with different building façades are carried out to investigate the accuracy of the calculation model.
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