The restorative potential of soundscapes: A physiological investigation Oleg Medvedev a , Daniel Shepherd a,⇑ , Michael J. Hautus b a Faculty of Health, Auckland University of Technology, New Zealand b School of Psychology, The University of Auckland, New Zealand article info Article history: Received 3 August 2014 Received in revised form 27 February 2015 Accepted 11 March 2015 Available online 29 March 2015 Keywords: Soundscapes Emotion Subjective evaluation Physiological recordings abstract Acoustic environments can have negative or positive effects on human health and wellbeing. Two studies investigating the impact of soundscapes on physiological measures obtained after a stressor or a period of rest, are reported. Subjective appraisals of the soundscapes were also considered when examining the relationship between soundscape and physiological response. Following a stress task, larger decreases in heart rate were associated with the least eventful, soundscapes. When at rest, sounds perceived as pleasant produced lower skin conductance levels compared to sounds perceived as unpleasant. Together these findings suggest that autonomic function during stress recovery and at rest can be influ- enced by subjective response to the acoustic environment. Further, the co-variance between subjective estimates of, and physiological response to, soundscapes suggests there is some worth in developing self-report soundscape surveys as a tool to use when considering soundscapes accessible to the public. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction Humans relate to their acoustic environments on an emotional level by interpreting the sensory information they afford, this giv- ing rise to the concept of the soundscape: ‘‘the acoustic environ- ment as perceived and understood, by people, in context’’ [1]. In particular, soundscape characteristics mark an environment as a desirable or undesirable place to occupy, as uniquely judged by the individual. Localities hosting acoustic stressors (i.e., noise) tend to induce negative emotions, and motivate an avoidance response (the so called defensive motivation system), while localities free from such stressors may induce positive emotions and motivate an approach response (the appetitive motivation system). Generally, people are motivated to seek places that minimize stress and maximize restoration. As a consequence, town planners, archi- tects, and acousticians work together to provide such areas: typi- cally parks, green spaces, and natural or wilderness areas. There is evidence suggesting that quiet areas make a positive contribution to public health [e.g., 2] and enhance physiological recovery from stress [3]. It is argued that natural environments can facilitate restorative physiological processes by either inducing positive emotions [4] and ‘‘undoing’’ the physiological changes brought about by negative emotional states [5], by restoring attentional capacity and reducing mental exhaustion [6], or a combination of the two [7]. To date, however, much of the research has been biased towards visual stimuli, focusing on pictures and videos of natural environments or urban settings [8], either with- out sound, without exploring interaction effects [9], or without controlling for important acoustical variables such as sound pres- sure level [3]. Physiological measures such as heart rate (HR) and skin conduc- tance level (SCL) reflect autonomic activity, whereby the sympa- thetic (‘‘Fight or flight’’) or parasympathetic (‘‘rest and digest’’) branches adopt a dynamic balance depending on the demands of the hosting environment. For both visual and auditory stimuli, autonomic measures such as HR and SCL co-vary with self-report levels of valence (i.e., ‘‘pleasantness’’) and arousal (i.e., degree of perceived autonomic response), respectively [10], results that are consistent with the valence–arousal model of emotional response [11]. Intrinsic to the valence–arousal model is the role of cognitive evaluations of sound, and thus the importance of collecting both physiological and subjective ratings when undertaking investiga- tions of the covariance between environmental factors and human response. The importance of subjective assessment of soundscapes has recently been explored in the literature [12], supporting a sur- vey approach to soundscape impacts. However, self-report surveys measuring emotional responses to soundscapes risk over- or under-estimation due to response biases, and objective physiologi- cal measures coupled to subjective soundscape evaluations have been recommended [13]. Hume and Ahtamad [13], adopting an approach very similar to Bradley and Lang [10], reported that http://dx.doi.org/10.1016/j.apacoust.2015.03.004 0003-682X/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: Department of Psychology, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand. Tel.: +64 9 921 9999; fax: +64 9 921 9780. E-mail address: daniel.shepherd@aut.ac.nz (D. Shepherd). Applied Acoustics 96 (2015) 20–26 Contents lists available at ScienceDirect Applied Acoustics journal homepage: www.elsevier.com/locate/apacoust