Potential restorative effects of urban soundscapes: Personality traits, temperament, and perceptions of VR urban environments

https://doi.org/10.1016/j.landurbplan.2021.104188Get rights and content

Highlights

  • Urban environments with preferred soundscapes have restorative potential effects.

  • New criteria were introduced based on restoration-related semantic terms.

  • Physically low-frequency content in a sound environment may affect restoration.

  • Participants’ overall space preference is key to determine restoration effects.

  • Individual traits are examined in depth as they affect perception of soundscapes.

Abstract

This study investigated the potential restorative (PR) effects of urban soundscapes. To establish a new set of PR criteria for urban environments, this study recreated 10 urban sites in virtual reality, instead of using the typical method of questionnaires. A list of restoration-related semantic terms was derived from narrative interviews of 50 subjects who freely expressed their perceptions of the space. PR criteria were determined based on the derived list and two groups were found: the PR group and potential non-restorative group. The objective characteristics of urban soundscapes—acoustic and visual characteristics and characteristics of moving objects—were analyzed. Participants provided their subjective responses regarding sound source identification, perceived affective quality, and overall quality. The Temperament and Character Inventory-Revised-Short Version and Satisfaction with Life Scale were utilized to analyze participants’ individual characteristics. Based on it, a model was developed to predict whether PR criteria could be satisfied, which was 82.6% accurate (85.9% specificity, 71.8% sensitivity). It was determined that the overall level of preference regarding an urban soundscape is a significant factor in satisfying PR criteria. In particular, the design and planning of urban spaces should aim to reduce a space’s loudness and increase the revisitation rate to promote the restoration of the urban residents’ mental health. Furthermore, for individuals, a trait based on acquired experience has a greater impact on the PR effects of urban soundscapes than innate temperament. This study’s findings can serve as supporting data to design sustainable and health-promoting urban soundscapes.

Introduction

Environmental noise caused by the rapid urbanization of modern society negatively impacts the health and well-being of urban dwellers, causing stress as well as mental and physiological problems; hence, there is an amplified desire for restoration amid stressful urban life (Basner et al., 2014, Stansfeld et al., 2000). Active use of green infrastructure during urban planning processes promotes stress reduction in city residents (Navarrete-Hernandez & Laffan, 2019). Additionally, the following measures have been proposed to reduce environmental noise: controlling physical noises, redesigning spaces using building materials or noise barriers to control noise transmission, and remodeling urban spaces based on the perspectives of residents affected by noise (European Union, 2002, World Health Organization (WHO), 2018).

However, approaching the issue of urban sound environment solely from the perspective of noise and reducing the noise level does not necessarily lead to improved satisfaction (Kang & Schulte-Fortkamp, 2016). Therefore, instead of using the existing noise management approach that considers noise as waste, a new soundscape concept has emerged that defines wanted sound as a resource and attempts to resolve problems in the sound environment from the perspective of preferred sounds (Brown, 2010, Raimbault and Dubois, 2005, Schafer, 1993, Southworth, 1969). Through cooperation among various interested parties, such as architects, acousticians, and researchers, strategies can be designed to amplify wanted sounds (water or nature sounds) while eliminating or reducing unwanted sounds (traffic noise or other noise). As such, practical design elements, such as vegetation, noise barriers, topography designs, or reducing source activity can be applied to the soundscape to affect unwanted noise (Brown, 2012, Cerwén et al., 2017).

Many studies have examined the restorative effects of positive soundscapes (Aletta et al., 2018, Herranz-Pascual et al., 2019, Zhao et al., 2018). Studies have investigated how the distinct psychological and physiological effects of natural environments (such as green space, and waterfronts) affect the restorative capacity of soundscapes. To understand the mechanism behind such restorative effects, an examination of Attention Restoration Theory (ART; Kaplan, 1995, Kaplan and Kaplan, 1989) and Stress Recovery Theory (SRT; Ulrich, 1983, Ulrich et al., 1991) is beneficial. Both theories assume that environments restore the psycho-physiological energy of urban residents experiencing ego depletion. ART emphasizes attention restoration and reflection and establishes four components of an environment’s restorative effects: being away, extent, fascination, and compatibility. It also posits that experiencing environments restores both individuals’ psycho-physiological energy and their cognitive resources, including attention and memory. SRT, a representative theory regarding how the natural environment alleviates stress reactions, is also referred to as psycho-evolutionary theory. It proposes that emotional and perceptional reactions in the natural environment could alleviate stress through various psychological and physiological means (Ulrich et al., 1991). Han (2003) tested the validity of self-rating restoration scales by comparing the results of various survey responses across natural and laboratory environments. He determined that an acceptable range of similar results could be obtained regardless of the type of scale that was used. Measures such as perceived restorativeness soundscape scale have been proposed to evaluate the subjective restorative effects of soundscapes in the field. These were tested and verified within particular urban functional areas, such as parks (Payne, 2013, Payne and Guastavino, 2018). Other studies demonstrated that natural environments improved individuals’ cognitive functions (Shu and Ma, 2019, Van Dijk-Wesselius et al., 2018), fostered stress reduction, and promoted positive emotions (Aletta et al., 2018, Choe et al., 2020, Medvedev et al., 2015). Many studies have also been conducted on the restorative effects of natural environments from a psychological perspective using questionnaires. Scale-based questionnaires are useful in quantifying a subject's psychological restoration response. However, the use of close-ended questionnaires to conduct evaluations may cause acquiescence and demand characteristics bias, as this method can force participants to focus on the evaluation of specific items (Furnham, 1986). We overcame such limitations by introducing a new set of criteria to determine potential restorative (PR) effects (PR criteria) based on the voluntary emotional expressions of participants regarding urban soundscape experiences.

Other studies have investigated the restorative effects of soundscapes from a physiological perspective. Physiological response indicators, such as heart rate (HR), HR variability (HRV), R-wave amplitude (ΔR), skin conductance level (SCL), respiration rate (RR), respiratory frequency (RF), respiratory depth (RD), and electroencephalography (EEG) have been examined. These studies indicate that natural soundscapes can lead to positive changes in physiological responses (Alvarsson et al., 2010, Hume and Ahtamad, 2013, Li and Kang, 2019, Medvedev et al., 2015, Yu et al., 2018). By investigating overall physiological indicators, Li and Kang (2019) determined that soundscapes that include natural sounds reduce the levels of HR, RF, and RD and increase the levels of ΔR, HRV, α-EEG, and β- EEG. A multitude of studies have already been conducted on the restorative effects of natural environments, sufficiently verifying their positive effects (Collins et al., 2020, Huang et al., 2020, Lachowycz and Jones, 2013).

In this study, the term “natural environment” includes green areas such as forests, valleys, grasslands, and parks, and waterfronts such as seas, lakes, wetlands, and streams, and is defined as a setting that is contrary to the urban environment. While many studies have examined the restorative effects of natural environments, few have examined the restorative effects of urban environments, despite their potentially frequent occurrence (Krzywicka & Byrka, 2017). Studies have presented urban environments in opposition to natural environments, representing the former as negative stimuli that hinder restorative environmental effects (Park et al., 2020, Tsunetsugu et al., 2013, Yu et al., 2018). Furthermore, most settings used to evaluate urban environments portray unpleasant situational components, including traffic noise, industrial areas, and buildings (Medvedev et al., 2015, Yu et al., 2018). However, some cultural facilities in urban environments, like museums and monasteries, can aid in urban residents’ mental recovery (Kaplan et al., 1993, Ouellette et al., 2005, Packer, 2008). Moreover, one study indicated that the HRV response in an urban environment does not differ much from the physiological response in a forest environment; in comparison with office or minibus environments, the urban environment can trigger a physiological restoration effect. (Stigsdotter, Corazon, Sidenius, Kristiansen, & Grahn, 2017). Accordingly, studies have investigated how cultural activities in urban environments, such as concerts, plays, and sporting events, contribute to the health and well-being of urban residents and increase life satisfaction (Chick et al., 2016, Johansson et al., 2001). Moreover, interesting and attractive urban environments can reduce stress and improve urban residents’ moods (Karmanov & Hamel, 2008).

Urban designs generally aim to enhance the beauty, functionality, and sustainability of cities, while considering design factors such as buildings and infrastructure during planning (Carmona, Heath, Tiesdell, & Oc, 2010). As Kaplan (1995) suggested, any environment has the latent potential for restorative qualities, meaning that all design elements should be examined closely. As research into the restorative effects of urban environments has been insufficient, the PR effects of urban soundscapes must be examined by focusing on the diverse functions of urban locations.

Differences in individuals’ lifestyles, health, expectations, and sociodemographic characteristics change soundscape perception (Herranz-Pascual et al., 2010, Jo and Jeon, 2020a). Personality traits, especially emotional stability, affect how individuals evaluate soundscape quality, particularly its perceived pleasantness and eventfulness (Lindborg & Friberg, 2016).

Studies that examine the effect of individual differences on restorative effects focus on factors like noise sensitivity and environmental preference (Lercher et al., 2016, Ojala et al., 2019, Wilkie and Stavridou, 2013). Wilkie and Stavridou (2013) investigated the restorative effects of environments according to individuals’ environmental preferences and determined that the PR effect of an environment increased when the participants’ experiences were congruent with their preferences. Interestingly, individuals who preferred urban environments perceived a similar level of restorative effect for both natural and urban environments. Ojala et al. (2019) showed that urban-natural orientedness and noise sensitivity triggered differences in psychological restoration and concluded that urban environments cannot restore noise-sensitive and low-urban-oriented persons.

It has also been shown that individuals perceive the affordance of nature differently (Faehnle, Bäcklund, Tyrväinen, Niemelä, & Yli-Pelkonen, 2014). Moreover, the restoration effect varies depending on an individual's life cycle or work environment, and people with health problems tend to favor natural environments (Korpela & Ylén, 2009). The purpose of visiting an environment is an important factor that triggers these individual differences; people who visit a space with the intention of alleviating stress tend to show a greater restoration effect than people who do not (von Lindern, Bauer, Frick, Hunziker, & Hartig, 2013). The restoration effect also differs for each individual depending on their behavioral characteristics. An experience of the natural environment does not have any restoration effect on people with overt behavioral syndromes that include excessive competitiveness, striving for achievement, and aggressiveness (Twedt, Rainey, & Proffitt, 2019).

There are limited studies on restoration effects depending on individual differences in terms of preference, but some studies do examine individual differences in detail, including personal characters and satisfaction of life (Gao et al., 2019, Van den Berg et al., 2003). In particular, no study examines restoration effects among individuals in terms of soundscape. This study is unique in that it investigates both the PR effects of diverse urban soundscapes and the detailed differences between individuals’ perceptions of those soundscapes based on personality and temperament.

This study investigates the PR effects of urban soundscape experiences, focusing on urban environments that fulfill different functions and asking the following research questions:

What influencing factors determine the PR effects of urban soundscapes?

What are the differences between soundscape perceptions in the PR and potential non-restorative (PNR) groups?

How do the restorative effects of urban soundscapes differ according to individual personality?

Section snippets

Research framework

The research framework of this study is as follow. First, audio-visual data on urban environments were collected. Virtual reality (VR) technology was used to create life-like evaluation environments within a (restricted) laboratory setting. In Step 1, we analyzed the objective characteristics of urban soundscapes, specifically the acoustic and visual characteristics of urban soundscapes as well as those of moving objects. In Step 2, the participants’ subjective responses were investigated.

Objective characteristics of evaluation sites

Each evaluation site’s objective soundscape characteristics were analyzed, including acoustic and visual characteristics and the characteristics of moving objects (Table 2). First, examination of the acoustic parameters demonstrated that the range of LAeq was 54.8–80.6 dB, the range of LA10-A90 was 4.1–17.6 dB, and the range of LCeq-Aeq was 3.7–20.3 dB. As the difference between the minimum and maximum values of each parameter is more than 10 dB, these ranges adequately represent the soundscape

Design strategy for urban soundscapes

This study proposes a soundscape design strategy based on a prediction model for PR effects, which was created using data for diverse soundscape variables. This strategy would provide urban residents with a pleasant and health-promoting environment. Urban environments should be designed to reduce low-frequency acoustic characteristics of soundscapes to increase PR effects. This method is based on the evidence that the objective characteristics of soundscapes, LCeq-Aeq, had the greatest negative

Conclusions

This study investigates PR effects that occur when individuals experience the soundscapes of urban environments, which include a variety of functions. To achieve this, we collected the results of the participants’ open responses regarding their perceptions of soundscapes, investigated the connection between terms related to restoration and to semantic terms, and established a new set of PR criteria. To create a prediction model that satisfies the PR criteria, we analyzed the objective

Funding

This research was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (Ministry of Science and ICT [MSIT]; no. 2020R1A2C2009716). This research was supported by the Bio & Medical Technology Development Program of the NRF and the Korea government MSIT (grant no. 2019M3E5D1A01069363].

Authors’ contributions

Conceptualization, J.Y.J. and H.I.J.; Formal analysis, H.I.J.; Funding acquisition, J.Y.J.; Investigation, H.I.J.; Methodology, H.I.J.; Project administration, J.Y.J.; Supervision, J.Y.J.; Visualization, H.I.J.; Writing - original draft, H.I.J.; Writing - review & editing, H.I.J., J.Y.J., K.L.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

We thank all the volunteers who participated in the research. We particularly wish to thank Rosa Seo, a member of Hanyang University’s Architectural Acoustics Laboratory, for her assistance with the experimental setup and evaluation process.

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