Field study on the influence of spatial and environmental characteristics on the evaluation of subjective loudness and acoustic comfort in underground shopping streets

A large-scale measurement and subjective survey was undertaken in five underground shopping streets to determine the influence of spatial and environmental characteristics on users' subjective loudness and acoustic comfort. The analysis on the spatial characteristics shows that the subjective loudness is higher in "street type" than in "square type" underground shopping streets when the equivalent continuous A-weighted sound pressure level (LAeq) is relatively high (75 dBA). Acoustic comfort is higher in "square type" than in "street type" underground shopping streets where LAeq is relatively low (55 dBA). Considering spatial functions, it is found that acoustic comfort is higher in a dining area than in a shopping area. In terms of environmental characteristics where air temperature, relative humidity, luminance and visual aspect were considered, the subjective loudness is influenced by humidity and luminance, with correlation coefficients of 0.10-0.30. The evaluation of acoustic comfort is influenced by air temperature, humidity, and luminance, with correlation coefficients of 0.10-0.40. There are significant correlations between the evaluation of environmental factors and subjective loudness, as well as, acoustic comfort. The correlation coefficients are 0.10-0.50. Moreover, respondents' attitude to sound environment could influence their evaluation of subjective loudness and acoustic comfort.