The effects of sound source visibility on noise annoyance

Among all the multi-sensory interactions, audio-visual interaction is one of the topics which has attracted the greatest attention in relation to human sound perceptions. Previous studies indicated that road traffic or wind turbine noise would invoke higher noise annoyance ratings if the road or wind turbine was visible. Up to now, most of these studies were mainly focused on unwanted sounds. However very few investigated the effect of the visibility of wanted sound sources (e.g. water sound) on noise annoyance responses. The aim of the study is to reveal the effect of visibility of different types of neighborhood sceneries on noise annoyance responses at different sound pressure levels. In addition, it aims to investigate whether noise annoyance responses will differ if the types of sound perceived by individuals do not match with the visible sound sources. In this study, both wanted (water sound) and unwanted (road traffic) sound have been studied through a series of laboratory experiments. The results of the study found that the effect of source visibility on noise annoyance differed at different sound pressure levels of road traffic. Noise annoyance ratings would be higher if the sound source (irrespective of wanted sound or unwanted sound) was visible and when sound pressure level of traffic was at 65 dBA. The results of the study can provide valuable insights for building designers and urban planners to make use of visibility of sound sources to provide better acoustic environment and mitigate noise annoyance induced by road traffic.