Impact of spatial factors of environmental sounds on psychological and physiological responses: A virtual reality study on direction and distance

The acoustic environment has a significant impact on our emotional well-being and overall health. While earlier research in environmental noise and soundscape has studied acoustic/psychoacoustic and semantic factors of sound sources on human perception and emotional responses, the spatial factors of sound sources in relation to the listener remain underexplored. This gap may be attributed to the limitations of conventional experimental techniques in replicating spatial characteristics, whereas the advent of virtual reality (VR) technology provides a new opportunity to overcome these constraints. In this research, we utilised VR in a laboratory experiment involving forty-five participants across three countries to investigate the effects of spatial factors, particularly the distance and direction of sound sources, on emotional responses, assessed through both self-reported ratings and physiological measures of electrodermal activity (EDA). The results indicate that the spatial positioning of sources has statistically significant effects on emotional responses. Frontal sources are perceived as significantly more positive and elicit significantly lower EDA than lateral or rear sources (e.g., Δ_max = 0.9 on 9-point scale). Closer sources are rated significantly more arousing (for both wanted and unwanted sources; Δ_max = 0.7 and 0.6, respectively) and significantly more negative (for unwanted sources; Δ_max = −1.3) than distant ones, even when the received sound level remains constant. The contributions of the spatial factors are comparable to, if not greater than, those of sound level. These findings provide a fundamental evidence base with wide-ranging implications, extending from urban planning, architecture, and landscape to soundscape design and beyond.