Statistical analyses
To validate the physiological and psychological effects of auditory stimulation using nature and city sounds, we compared the physiological and psychological responses to nature and city sounds during auditory stimulation by paired t-test and Wilcoxon signed-rank test, respectively. In addition, as a subanalysis, we compared the physiological status before (NIRS, 10 sec; HRV and HR, 60 sec) and during the stimulation (60 sec) of nature sounds. The Statistical Package for the Social Sciences software version 25.0 (IBM, NY) was used, and a 