Combined effects of dominant sounds, conversational speech and multisensory perception on visitors’ acoustic comfort in urban open spaces

People’s perceptions are an important part of a landscape; however, little attention is paid to acoustic comfort in landscape planning and design for various urban open spaces. This study was primarily conducted to examine the effects of dominant sound types, conversational speech and multisensory perception on the subjective evaluations of acoustic comfort of open space based on an on-site questionnaire survey in typical urban open spaces. The results showed that as the first dominant sounds moved from being mechanical and anthropogenic to being nature-related, the acoustic comfort evaluations increased significantly within the dominant sound identification dimension. The subjective loudness of the background sound level and perceived speech intelligibility were significant indicators for acoustic comfort in each type of open space within the conversational speech perception dimension; decreased subjective loudness could contribute the most to higher acoustic comfort evaluations among indicators at the same perceptual levels (on a five-point scale). Olfactory comfort, thermal comfort, sunshine, and visual aesthetic quality of view were significant indicators for acoustic comfort depending on different types of open spaces within the multisensory perception dimension; increasing positive olfactory perception to the ‘very comfortable’ level could promote higher acoustic comfort evaluations than other indicators at the same perceptual level in multisensory interactions. In terms of the combined effects of the indicators within the three dimensions and the visitors’ sociodemographic factors, the combined indicators would better fit in predicting the acoustic comfort evaluations, in which the indicators of conversational speech and the multisensory perception were key determinants with high important values contributing to acoustic comfort evaluations.