Acoustic characteristics of urban streets in relation to scattering caused by building facades

The relationship between scattering and the acoustic characteristics of urban streets is examined by computer simulation. The simulation method is a combination of the image method for specular reflection and the radiosity method for scattering reflection. The findings are as follows: (1) the effect of scattering on the SPL appears as an increase at short distances and as a decrease at great distances. The range of the increase in SPL is larger in high-facade streets. In low-facade streets, the primary effect of scattering on SPL is a decrease in SPL. (2) In low-facade streets the reverberation time is determined by the sum of absorption coefficient and scattering coefficient. In contrast, in high-facade streets, the reverberation time is determined by the absorption coefficient. (3) The simulated result for the reverberation time shows good agreement with measured value in actual streets. (4) The estimated values for the sum of absorption coefficient and scattering coefficient of facades of actual urban streets range from 0.1 to 0.25.