Sounds of Nature in the City: No Evidence of Bird Song Improving Stress Recovery.

Pontus Thorsson,Johan N Lundström,Marcus Hedblom,Martin Schaefer,Bengt Gunnarsson,Igor Knez

doi:10.3390/ijerph16081390

Abstract

Noise from city traffic is one of the most significant environmental stressors. Natural soundscapes, such as bird songs, have been suggested to potentially mitigate or mask noise. All previous studies on masking noise use self-evaluation data rather than physiological data. In this study, while respondents (n = 117) watched a 360° virtual reality (VR) photograph of a park, they were exposed to different soundscapes and mild electrical shocks. The soundscapes—“bird song”, “bird song and traffic noise”, and “traffic noise”—were played during a 10 min recovery period while their skin conductance levels were assessed as a measure of arousal/stress. No significant difference in stress recovery was found between the soundscapes although a tendency for less stress in “bird song” and more stress in “traffic noise” was noted. All three soundscapes, however, significantly reduced stress. This result could be attributed to the stress-reducing effect of the visual VR environment, to the noise levels being higher than 47 dBA (a level known to make masking ineffective), or to the respondents finding bird songs stressful. Reduction of stress in cities using masking with natural sounds requires further studies with not only larger samples but also sufficient methods to detect potential sex differences.

Highlights

The health and well-being of an urban population are strongly influenced by the characteristics of the urban systems where factors such as density of houses, the presence of green spaces, urban heat island effects, population densities, traffic, air pollution, and noise pollution all have an impact [1].when it comes to environmental stressors associated with disease, noise pollution has been identified as one of the most significant factors [2,3,4,5,6,7]
We discuss the importance of the context of the physiological responses to the soundscapes: (i) the link to the visual feature of urban green; (ii) masking sounds; (iii) dBA levels; (iv) demography, such as sex aspects and dose-response for the setting, for example, the time spent in the experimental setup; (v) the physiological tests of stress in the experimental set up; and (vi) the conclusions with recommendations based on results
We found no significant results for a reduction in physiological stress when masking traffic noise with bird songs

Summary

Introduction

The health and well-being of an urban population are strongly influenced by the characteristics of the urban systems where factors such as density of houses, the presence of green spaces, urban heat island effects, population densities, traffic, air pollution, and noise pollution all have an impact [1].when it comes to environmental stressors associated with disease, noise pollution has been identified as one of the most significant factors [2,3,4,5,6,7]. In larger European cities, half the population is likely to be exposed to noise levels that produce physiological and psychological stresses that affect health and well-being (The European Directive COM 2002/49/EC), a problem that has been predicted to increase, leading to even higher societal costs [8,9]. Whereas research into this topic has traditionally. Public Health 2019, 16, 1390; doi:10.3390/ijerph16081390 www.mdpi.com/journal/ijerph

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