Effects of nature sounds on the attention and physiological and psychological relaxation

This study aims to verify the effects of nature sounds on attention, and physiological and psychological relaxation. Twenty-six university students (mean age: 21.5 ± 1.9 years) participated in this study, and the experiment was conducted with one person at a time. A mixed sound of valley water and birds in a forest environment was used as the nature sound, and a road traffic sound was used as the urban sound (control). The participants performed the following steps: (1) closed their eyes and rested for 1 min; (2) opened their eyes and completed attention tasks while hearing nature or urban sounds for 1 min; (3) closed their eyes again and rested while hearing the same sound for 1 min. We used Harris and Harris grid for the attention task. We measured the participants’ oxy-hemoglobin concentration, heart rate variability, and heart rate for physiological evaluation, and used semantic differential method, and profile of mood states for psychological evaluation. As a result, ① There was no significant difference in the results of the attention task; however, the scores were slightly higher when hearing nature sound. ② The oxy-hemoglobin concentration and heart rate was lower, and parasympathetic nerve activity was enhanced when hearing nature sound than when hearing urban sound. ③ Once participants heard nature sound, they felt more comfortable, relaxed, and natural, and the negative mood state was lower, while the positive mood state was higher than urban sound. This suggests that hearing nature sounds may be an effective way to relieve stress in everyday life.