Development of Indicators for the Soundscape in Urban Shopping Streets

This paper aims to find a series of objective indicators that can fully describe the soundscapes of urban shopping streets. The perceptual and physical features of soundscapes in urban shopping streets have been investigated via field surveys and a laboratory study. Using the semantic differential method, the perception structure of shopping street soundscapes was initially analysed, and five major perceptual factors were identified that explained 64% of the total sample variance, including preference, loudness, communication, playfulness and richness. Each perceptual factor explained approximately 10% to 15% of the total variance, which showed that they shared very similar importance in the representation of the overall soundscapes in urban shopping streets. Based on this semantic differential analysis, a laboratory study was performed to investigate the relationship between perceptual factors and physical indicators. Sound levels and psychoacoustic indicators were initially considered to be the most common indicators. The results showed that there were significant correlations between these indicators and three perceptual factors, including preference, loudness and communication. A new indicator (dynamic spectrum centre or DSC) was then developed in this study based on the concepts of spectrum gravity centre analysis and temporal variety analysis. This indicator combined spectral and temporal analysis to describe the contents of background sounds and sound events. The DSC indicator was found to have a significant correlation with the other two perceptual factors (playfulness and richness). Increasing the variability of the sound event (a higher standard deviation of DSC_E) could make soundscape more playful and richer.