Birdsong good for your wellbeeing

5. januar 2023 | Relaxound

• Fokus på bæredygtighed
• Design
• Have & uderum
• Bolig & brugskunst

downloadKun til redaktionelt brug

Significance
This study examines evidence of the health benefits of natural soundscapes and quantifies the prevalence of restorative acoustic environments in national parks across the United States. The results affirm that natural sounds improve health, increase positive affect, and lower stress and annoyance. Also, analyses reveal many national park sites with a high abundance of natural sound and low anthropogenic sound. Raising awareness of natural soundscapes at national parks provides opportunities to enhance visitor health outcomes. Despite more abundant anthropogenic sound, urban and frequently visited sites offered exposure to natural sounds associated with health benefits, making them a valuable target for soundscape mitigation. Our analysis can inform spatial planning that focuses on managing natural soundscapes to enhance human health and experiences.

Abstract
Parks are important places to listen to natural sounds and avoid human-related noise, an increasingly rare combination. We first explore whether and to what degree natural sounds influence health outcomes using a systematic literature review and meta-analysis. We identified 36 publications examining the health benefits of natural sound. Meta-analyses of 18 of these publications revealed aggregate evidence for decreased stress and annoyance (g = −0.60, 95% CI = −0.97, −0.23) and improved health and positive affective outcomes (g = 1.63, 95% CI = 0.09, 3.16). Examples of beneficial outcomes include decreased pain, lower stress, improved mood, and enhanced cognitive performance. Given this evidence, and to facilitate incorporating public health in US national park soundscape management, we then examined the distribution of natural sounds in relation to anthropogenic sound at 221 sites across 68 parks. National park soundscapes with little anthropogenic sound and abundant natural sounds occurred at 11.3% of the sites. Parks with high visitation and urban park sites had more anthropogenic sound, yet natural sounds associated with health benefits also were frequent. These included animal sounds (audible for a mean of 59.3% of the time, SD: 23.8) and sounds from wind and water (mean: 19.2%, SD: 14.8). Urban and other parks that are extensively visited offer important opportunities to experience natural sounds and are significant targets for soundscape conservation to bolster health for visitors. Our results assert that natural sounds provide important ecosystem services, and parks can bolster public health by highlighting and conserving natural soundscapes.

Results
Systematic Review and Meta-Analysis.
In our systematic review of peer-reviewed literature, only 19% of studies examining the health benefits of natural sounds (n = 7) measured traditional health outcomes, including heart rate, blood pressure, perceived pain, skin conductance, cortisol, and t-wave amplitude. Other studies examined the potential precursors along the pathway to health, including metrics of perception, mood, and cognitive performance. For 52% of outcomes measured (13 studies in the meta-analysis), we expected to see an increase due to natural sound (i.e., health and positive affect), and in the other 48% (12 studies in the meta-analysis), we expected to see a decrease due to natural sound (i.e., stress and annoyance).
Most studies (61%, n = 22) occurred in a laboratory or hospital setting rather than in the field. Research occurred in 11 different countries, with the largest number in Sweden (22%, n = 8). Studies had a mean sample size of 150.6 (±304.3 SD) and a mean quality score, based on the Quality Assessment Tool for Quantitative Studies, of 1.8 (±0.4 SD; SI Appendix, Fig. S1).
The overall mean effect size for health and positive affect outcomes was 1.63 (95% CI = 0.09, 3.16), corresponding to a 184% overall improvement in groups exposed to natural sounds relative to comparison groups (Fig. 1). The large variance in effect sizes was due to one study with particularly large effect sizes (28). The overall mean effect size for stress and annoyance outcomes was −0.60 (95% CI = −0.97, −0.23), corresponding to a 28% overall decrease in groups exposed to natural sounds relative to comparisons We found significant heterogeneity between effect sizes in all models (Q > 248.4, P < 0.001), suggesting that moderators not considered in the model influenced the health benefits of natural sound exposure. We found no obvious pattern of publication bias in the funnel plot (SI Appendix, Fig. S1). If we only included studies with high quality scores (≤1.5), mean effect sizes of models were still significant (SI Appendix, Table S1).
Of the three types of natural sounds (birds, water, and mixed), we found that water sounds had the largest mean effect size for health and positive affect outcomes (2.01, 95% CI = 0.35, 3.67), and bird sounds had the largest mean effect size for stress and annoyance (1.11, 95% CI = −1.82, −0.4, Fig. 2). Yet, relatively few studies tested bird sounds explicitly (11 effect sizes in 2 studies). Comparing natural sound and noise to noise had the largest mean effect size for health and positive affective outcomes (9.9, 95% CI = 8.46, 11.29), although only one study tested this effect. Comparing natural sound to noise had the largest mean effect size for both health and positive affective outcomes (1.7, 95% CI = 0.16, 3.24) and stress and annoyance (−0.81, 95% CI = −1.21, −0.40, Fig. 2). Comparing more natural sounds versus fewer natural sounds and natural sounds versus no sound also significantly improved health and positive affect and decreased stress and annoyance. The weakest contrast in our results was between natural sounds and natural sounds mixed with noise. Only one study tested the influence of more natural sounds versus fewer (11 effect sizes).