The effect of water sound level in virtual reality: A study of restorative benefits in young adults through immersive natural environments

Virtual Reality (VR) can bring a person to a restorative natural environment-an immersive experience containing elements from blue and green space that help reduce stress and anxiety. However, the effect of different water sound levels on psychological and physiological health remains unclear. This study used a VR natural environment-combining forest scene and waterfall sounds-to compare the low and high water sound levels' effects on individuals' psychological (affective quality of place and state anxiety relief) and physiological benefits (heart rate variability). We focused on two comparisons in each of the two dimensions: (1) a before-and-after comparison that analyzes the effectiveness of the water sounds, and (2) a low-and-high comparison that investigates the differences between the two sound levels. A total of 45 university students (aged between 19 and 23) participated in the experiment. The results show that both low- and high-decibel levels improved in psychological dimension, and decrease individuals' heart rates from anxiety status. More importantly, while the high-decibel served to awaken emotions, the low-decibel was more effective at calming emotions and relieving anxiety. Overall, we found that natural waterscape sounds relieve transient anxiety states and promote healthy autonomic nervous activity. This study provides evidence for the planning of healthy environmental interaction patterns and the design of urban soundscapes.