Sensitivity analysis of changes in human physiological indicators observed in soundscapes

The objective of this study was to determine changes in physiological indicators with time in different soundscapes and their correlation with the results of subjective restorative evaluation. Physiological indicators including the heart rate (HR), amplitude of the R-wave (ΔR), heart rate variability (HRV), electroencephalography alpha reactivity (α-EEG), electroencephalography beta reactivity (β-EEG), eye blink frequency (BF), respiratory frequency (RF), respiratory depth (RD), skin conductance level (SCL), and skin temperature (ST) were measured and analysed through audio-visual reduction in a laboratory, and the obtained data were compared with the answers to a perceived restorativeness soundscape scale survey. Through the analysis of variance by a repeated measures method, it was found that all physiological indicators (except for α-EEG) changed after one minute of measurements. Furthermore, BF and ST were not affected by the changes in the soundscape type, and the natural sound decreased the levels of HR, RF, and RD and increased the values of ΔR, HRV, α-EEG, and β-EEG. In addition, a canonical correlation analysis was performed to determine the correlation between the physiological indicators and subjective evaluation factors. The relationship between the physiological parameters measured within the first minute and results of subjective evaluation was relatively strong but insufficient for accurately interpreting the obtained physiological responses using only the subjective evaluation data.