Relationship between street scale and subjective assessment of audio-visual environment comfort based on 3D virtual reality and dual-channel acoustic tests

We examine the influence of street scales (the street width, building height, and street-width-to-building-height ratio, referred to as 'width-to-height ratio' in the paper) on visual, acoustic, and audio-visual comfort evaluation (as evaluated by a set of participants) in urban areas. In addition, we examine the relationships between the sound level and the abovementioned subjective comfort evaluation except the visual one. After measuring the street scales and recording the street visual information with a 3D camcorder, the virtual 3D models of the streets were generated. Meanwhile, dual-channel acoustic signals of the streets were collected. Subsequently, subjective tests were carried out using a 3D virtual reality with corresponding sounds using 164 participants. The analysis shows that subjective attitudes are directly related to the street scales. In particular, there is a strong positive correlation between audio-visual comfort and the street width-to-height ratio. In contrast, the three indicators (visual, acoustic, and audio-visual comfort) are strongly negatively correlated to the height, and this type of negative correlation is also observed between subjective indicators (except the visual one) and the sound level. Overall, the respondents found the audio-visual level most comfortable when the street width-to-height ratio is greater than 1, street width is within 20 m, height of street buildings is less than 26 m, and the sound level is less than 58 dBA. It is expected that these findings can aid designers in predicting the ideal audio-visual environment quality for urban streets.