The effects of audio-visual factors on perceptions of environmental noise barrier performance

As concerns on the adverse effects of noise pollution in the environment grow, the use of environmental noise barriers has increased. Noise barriers are commonly considered to be public structures that affect landscape quality. Hence, both acoustic and landscape issues need to be taken into consideration to design effective noise barriers in urban environments. This study aims to investigate the intersensory perceptions of noise barrier performance in terms of the spectral characteristics of noise reduction combined with visual impressions of five different barrier types: aluminum, timber, translucent acrylic, concrete, and vegetated barriers. Illustrations of five barrier types were taken in a real urban environment, and the noise reduction characteristics of these five barrier types were predicted based on their acoustic characteristics. Noise annoyance, preconceptions regarding the noise attenuation performance of the barrier, the esthetic preference, and the overall preference for noise barriers were assessed through laboratory experiments. Three different types of experiments were conducted: audio-only experiments, visual-only experiments, and audio-visual experiments. The results of the experiments revealed that noise reduction, particularly low frequency components, had a dominant effect on the perception of the noise-attenuating performance of barriers. The preconceptions of noise attenuation by barriers affected the overall preference for noise barriers at 55 dBA, while esthetic preferences for noise barriers were significant at 65 dBA. In addition, barriers covered with vegetation increased the perceived noise barrier performance with increasing esthetic preference and preconceptions of noise reduction. (C) 2014 Elsevier B.V. All rights reserved.