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Open AccessArticle

Physiological and Psychological Effects of Forest and Urban Sounds Using High-Resolution Sound Sources

1
Center for Environment, Health and Field Sciences, Chiba University, 6-2-1 Kashiwa-no-ha, Kashiwa, Chiba 277-0882, Japan
2
Department of Wood Engineering, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
3
JVCKENWOOD Victor Entertainment Corporation, 1-2-20 Higashi, Shibuya-ku, Tokyo 150-0011, Japan
4
Department of Nursing, Ishikawa Prefectural Nursing University, 1-1 Gakuendai, Kahoku, Ishikawa 929-1210, Japan
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Int. J. Environ. Res. Public Health 2019, 16(15), 2649; https://doi.org/10.3390/ijerph16152649
Received: 14 June 2019 / Revised: 19 July 2019 / Accepted: 21 July 2019 / Published: 24 July 2019
Exposure to natural sounds is known to induce feelings of relaxation; however, only few studies have provided scientific evidence on its physiological effects. This study examined prefrontal cortex and autonomic nervous activities in response to forest sound. A total of 29 female university students (mean age 22.3 ± 2.1 years) were exposed to high-resolution sounds of a forest or city for 60 s, using headphones. Oxyhemoglobin (oxy-Hb) concentrations in the prefrontal cortex were determined by near-infrared spectroscopy. Heart rate, the high-frequency component of heart rate variability (which reflects parasympathetic nervous activity), and the ratio of low-frequency to high-frequency (LF/HF) components (which reflects sympathetic nervous activity) were measured. Subjective evaluation was performed using the modified semantic differential method and profiles of mood states. Exposure to the forest sound resulted in the following significant differences compared with exposure to city sound: decreased oxy-Hb concentrations in the right prefrontal cortex; decreased ln(LF/HF); decreased heart rate; improved feelings described as “comfortable,’’ “relaxed,” and “natural”; and improved mood states. The findings of this study demonstrated that forest-derived auditory stimulation induced physiological and psychological relaxation effects. View Full-Text
Keywords: forest sound; natural sound; physiological relaxation effects; prefrontal cortex activity; autonomic nervous activity; near-infrared spectroscopy; heart rate variability; heart rate; semantic differential method; profile of mood states forest sound; natural sound; physiological relaxation effects; prefrontal cortex activity; autonomic nervous activity; near-infrared spectroscopy; heart rate variability; heart rate; semantic differential method; profile of mood states
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Jo, H.; Song, C.; Ikei, H.; Enomoto, S.; Kobayashi, H.; Miyazaki, Y. Physiological and Psychological Effects of Forest and Urban Sounds Using High-Resolution Sound Sources. Int. J. Environ. Res. Public Health 2019, 16, 2649.

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