Promoting Healthy and Supportive Acoustic Environments Going beyond the Quietness Printed Edition of the Special Issue Published in International Journal of Environmental Research and Public Health /www.mdpi.com/journal/ijerph Francesco Aletta and Jian Kang Edited by Promoting Healthy and Supportive Acoustic Environments Promoting Healthy and Supportive Acoustic Environments Going beyond the Quietness Special Issue Editors Francesco Aletta Jian Kang MDPI • Basel • Beijing • Wuhan • Barcelona • Belgrade • Manchester • Tokyo • Cluj • Tianjin Special Issue Editors Francesco Aletta Institute for Environmental Design and Engineering, University College London UK Jian Kang Institute for Environmental Design and Engineering, University College London UK Editorial Office MDPI St. Alban-Anlage 66 4052 Basel, Switzerland This is a reprint of articles from the Special Issue published online in the open access journal International Journal of Environmental Research and Public Health (ISSN 1660-4601) (available at: https: //www.mdpi.com/journal/ijerph/special issues/PHSAE). For citation purposes, cite each article independently as indicated on the article page online and as indicated below: LastName, A.A.; LastName, B.B.; LastName, C.C. Article Title. Journal Name Year , Article Number , Page Range. ISBN 978-3-03928-272-2 ( H bk) ISBN 978-3-03928-273-9 (PDF) Cover image courtesy of Tin Oberman. c © 2020 by the authors. Articles in this book are Open Access and distributed under the Creative Commons Attribution (CC BY) license, which allows users to download, copy and build upon published articles, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. The book as a whole is distributed by MDPI under the terms and conditions of the Creative Commons license CC BY-NC-ND. Contents About the Special Issue Editors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii Francesco Aletta and Jian Kang Promoting Healthy and Supportive Acoustic Environments: Going beyond the Quietness Reprinted from: Int. J. Environ. Res. Public Health 2019 , 16 , 4988, doi:10.3390/ijerph16244988 . . . 1 Angel M. Dzhambov, Iana Markevych, Boris Tilov, Zlatoslav Arabadzhiev, Drozdstoj Stoyanov, Penka Gatseva and Donka D. Dimitrova Lower Noise Annoyance Associated with GIS-Derived Greenspace: Pathways through Perceived Greenspace and Residential Noise Reprinted from: Int. J. Environ. Res. Public Health 2018 , 15 , 1533, doi:10.3390/ijerph15071533 . . . 5 Marcus Hedblom, Bengt Gunnarsson, Martin Schaefer, Igor Knez, Pontus Thorsson and Johan N Lundstr ̈ om Sounds of Nature in the City: No Evidence of Bird Song Improving Stress Recovery Reprinted from: Int. J. Environ. Res. Public Health 2019 , 16 , 1390, doi:10.3390/ijerph16081390 . . . 21 Sarah R. Payne and Neil Bruce Exploring the Relationship between Urban Quiet Areas and Perceived Restorative Benefits Reprinted from: Int. J. Environ. Res. Public Health 2019 , 16 , 1611, doi:10.3390/ijerph16091611 . . . 33 Shilun Zhang, Xiaolong Zhao, Zixi Zeng and Xuan Qiu The Influence of Audio-Visual Interactions on Psychological Responses of Young People in Urban Green Areas: A Case Study in Two Parks in China Reprinted from: Int. J. Environ. Res. Public Health 2019 , 16 , 1845, doi:10.3390/ijerph16101845 . . . 59 Gunnar Cerw ́ en Listening to Japanese Gardens: An Autoethnographic Study on the Soundscape Action Design Tool Reprinted from: Int. J. Environ. Res. Public Health 2019 , 16 , 4648, doi:10.3390/ijerph16234648 . . . 73 Gunnar Cerw ́ en and Frans Mossberg Implementation of Quiet Areas in Sweden Reprinted from: Int. J. Environ. Res. Public Health 2019 , 16 , 134, doi:10.3390/ijerph16010134 . . . 103 Karmele Herranz-Pascual, Itziar Aspuru, Ioseba Iraurgi, ́ Alvaro Santander, Jose Luis Eguiguren and Igone Garc ́ ıa Going beyond Quietness: Determining the Emotionally Restorative Effect of Acoustic Environments in Urban Open Public Spaces Reprinted from: Int. J. Environ. Res. Public Health 2019 , 16 , 1284, doi:10.3390/ijerph16071284 . . . 121 Francesco Aletta and Jian Kang Towards an Urban Vibrancy Model: A Soundscape Approach Reprinted from: Int. J. Environ. Res. Public Health 2018 , 15 , 1712, doi:10.3390/ijerph15081712 . . . 141 Daniel Steele, Edda Bild, Cynthia Tarlao and Catherine Guastavino Soundtracking the Public Space: Outcomes of the Musikiosk Soundscape Intervention Reprinted from: Int. J. Environ. Res. Public Health 2019 , 16 , 1865, doi:10.3390/ijerph16101865 . . . 159 v Jieling Xiao and Andrew Hilton An Investigation of Soundscape Factors Influencing Perceptions of Square Dancing in Urban Streets: A Case Study in a County Level City in China Reprinted from: Int. J. Environ. Res. Public Health 2019 , 16 , 840, doi:10.3390/ijerph16050840 . . . 197 Luis Hermida, Ignacio Pav ́ on, Antonio Carlos Lobo Soares and J. Luis Bento-Coelho On the Person-Place Interaction and Its Relationship with the Responses/Outcomes of Listeners of Urban Soundscape (Compared Cases of Lisbon and Bogot ́ a): Contextual and Semiotic Aspects Reprinted from: Int. J. Environ. Res. Public Health 2019 , 16 , 551, doi:10.3390/ijerph16040551 . . . 213 Francesco Aletta, Tin Oberman and Jian Kang Associations between Positive Health-Related Effects and Soundscapes Perceptual Constructs: A Systematic Review Reprinted from: Int. J. Environ. Res. Public Health 2018 , 15 , 2392, doi:10.3390/ijerph15112392 . . . 235 Mercede Erfanian, Andrew J. Mitchell, Jian Kang and Francesco Aletta The Psychophysiological Implications of Soundscape: A Systematic Review of Empirical Literature and a Research Agenda Reprinted from: Int. J. Environ. Res. Public Health 2019 , 16 , 3533, doi:10.3390/ijerph16193533 . . . 251 Armin Taghipour, Tessa Sievers and Kurt Eggenschwiler Acoustic Comfort in Virtual Inner Yards with Various Building Facades Reprinted from: Int. J. Environ. Res. Public Health 2019 , 16 , 249, doi:10.3390/ijerph16020249 . . . 271 Sonja Di Blasio, Louena Shtrepi, Giuseppina Emma Puglisi and Arianna Astolfi A Cross-Sectional Survey on the Impact of Irrelevant Speech Noise on Annoyance, Mental Health and Well-being, Performance and Occupants’ Behavior in Shared and Open-Plan Offices Reprinted from: Int. J. Environ. Res. Public Health 2019 , 16 , 280, doi:10.3390/ijerph16020280 . . . 291 Shan Shu and Hui Ma Restorative Effects of Classroom Soundscapes on Children’s Cognitive Performance Reprinted from: Int. J. Environ. Res. Public Health 2019 , 16 , 293, doi:10.3390/ijerph16020293 . . . 309 vi About the Special Issue Editors Francesco Aletta , AFHEA has been Research Associate at the Institute for Environmental Design and Engineering, The Bartlett, University College London since 2018. He was Postdoctoral Research Fellow at the Department of Information Technology of Ghent University from 2016 to 2018 and Research Associate at the School of Architecture of the University of Sheffield, working on the soundscapes of both indoor and outdoor spaces. He has been Visiting Lecturer at Birmingham City University and Visiting Professor at the Polytechnic Institute of Turin and the University of Roma Tre. His work on soundscape descriptors and predictive models has informed policy documents and international standards. He is Secretary of the Technical Committee for Noise of the European Acoustics Association. He serves on the editorial board of several peer-reviewed international journals in the fields of building and environmental acoustics, environmental psychology, and urban studies. Dr. Aletta has worked in soundscape studies for 10 years, with 70+ publications. He is the recipient of several research awards and funding for research equipment. He serves as a reviewer for 50+ journals and works as a referee for research projects for the Italian Ministry for Education, University, and Research. Jian Kang , FREng, FIOA, FASA, FIIAV, CEng has been Chair in Acoustics at the Institute for Environmental Design and Engineering, The Bartlett, University College London since 2018. He was Professor of Acoustics at the School of Architecture of the University of Sheffield from 2003 and is now Visiting Professor. He has also worked at the University of Cambridge, the Fraunhofer Institute of Building Physics in Germany, and Tsinghua University in China. He chairs the Technical Committee for Noise of the European Acoustics Association and the EU COST Action on Soundscape of European Cities and Landscapes. He was awarded the IOA Tyndall Medal in 2008, the Peter Lord Award in 2014, the NAS Lifetime Achievement Award in 2014, and the CIBSE Napier Shaw Bronze Medal in 2013. In addition, he is Fellow of the Royal Academy of Engineering. Professor Kang has worked in environmental and architectural acoustics for 30+ years, with 70+ research projects, 800+ publications, 90+ engineering/consultancy projects, and 20+ patents. His work on acoustic theories, design guidance, and products has brought major improvements to noise control in underground stations/tunnels and soundscape design in urban areas. He was the recipient of the prestigious Advanced ERC Grant Award and is currently working internationally on developing soundscape indices. vii International Journal of Environmental Research and Public Health Editorial Promoting Healthy and Supportive Acoustic Environments: Going beyond the Quietness Francesco Aletta * and Jian Kang * UCL Institute for Environmental Design and Engineering, The Bartlett, University College London (UCL), Central House, 14 Upper Woburn Place, WC1H 0NN London, UK * Correspondence: francesco.aletta@virgilio.it (F.A.); j.kang@ucl.ac.uk (J.K.); Tel.: + 44-(0)20-3108-7338 (J.K.) Received: 22 November 2019; Accepted: 30 November 2019; Published: 8 December 2019 When confronted with the topic of the quality of the acoustic environments, society and communities around the world tend to consider “sound” mainly in its negative facet of “noise”. This approach is reflected in a number of recommendations and prescriptions to reduce people’s exposure to excessive sound levels from transportation and industry, promoted by international institutions and authorities, such as the World Health Organization or the European Union [ 1 , 2 ]. Notwithstanding, such a strategy is not always e ff ective in delivering the desired enhancements in terms of health and quality of life, and this is because “quietness” and the pursuit of “silence” are not necessarily enough to define an acoustic environment of high quality [ 3 ]. Indeed, environmental sounds often have positive e ff ects on people, as they provide information, communicate safety, enable certain desirable activities, and, more generally, contribute to people’s appeasement and psychophysical well-being [ 4 , 5 ]. With the rapid increase of urbanization, more research is needed towards alternative approaches for the characterization, management, and design of urban acoustic environments that support (and not only allow) restoration, health, and better quality of life, as well as basic research on the mechanisms underpinning the perception of environmental sounds in context and how their experience might a ff ect health-related outcomes. Researchers in the environmental acoustics and soundscape domains are addressing these challenges by exploring new inter- and trans-disciplinary approaches to the characterization of the quality of the acoustic environments, new prediction and modeling methodologies for the acoustic environments and their qualities, and the relationships between sound, space, and behaviors in the built environment. From the 16 contributions published in this Special Issue, three main research themes were identified, which are briefly discussed below. 1. Rethinking Quiet Areas and Their Restorative Potential for Health and Well-Being The concept of perceived quietness has been thoroughly investigated over the years, partly also due to the emphasis put on this topic by major environmental agencies and policymakers. However, clear criteria that go beyond setting a mere sound level threshold for identifying areas where quietness can be experienced have not been internationally agreed on so far. The connection with natural elements and the experience of greenery seem to be prerequisites for quietness and similarly related perceptual constructs (e.g., tranquillity, calmness), and this applies at di ff erent urban scales; however, many aspects still need to be clarified, as some of the contributions of this Special Issue highlighted. Dzhambov et al. [ 6 ] show that more green areas in residential environments are associated with lower noise annoyance, whereas higher tree cover is similarly e ff ective only in small-radius bu ff er zones. Hedblom and colleagues [ 7 ] question a relatively well-established concept in soundscape studies, that birdsong typically facilitates stress recovery, by reporting that in their listening experiment, such e ff ect was, in fact, not observed. This more generally raises the point about what sound sources one would expect to contribute more to quietness perception, as well as supporting health and Int. J. Environ. Res. Public Health 2019 , 16 , 4988; doi:10.3390 / ijerph16244988 www.mdpi.com / journal / ijerph 1 Int. J. Environ. Res. Public Health 2019 , 16 , 4988 well-being. To some extent, the work by Payne and Bruce [ 8 ] also claims that the type of sounds heard and other aspects of a site experience are likely to be related to a non-linear relationship between sound levels and perceived restoration of an acoustic environment. Other contextual aspects might indeed play a role, such as audio–visual interactions in environmental perception, as suggested in the work by Zhang et al. [9] . Cerw é n [ 10 ] explores new autoethnographic approaches to propose possible actions, which are organized into three main categories (i.e., localization of functions, reduction of unwanted sounds, and introduction of wanted sounds) that designers can take into account when managing quiet areas in the urban realm. Finally, Cerw é n and Mossberg [ 11 ] report on a study about the implementation of quiet areas in accordance with the EU Environmental Noise Directive (END) of 2002, conducted with several municipalities in Sweden. They find out that at the local authority level, many initiatives have dealt with mapping and identification of quiet areas, but less has been done regarding their maintenance and enforcement, and this is likely to be a common issue for other (European) countries too. 2. Extending the Research Scope to More Soundscape Quality Dimensions, Contextual, and Physiological Factors While quietness is certainly a key theme in the current discourse about community noise, other dimensions might be relevant in di ff erent contexts to characterize the acoustic quality of public spaces. It is fair to assume that non-quiet spaces might still have the potential to promote positive user experiences of an urban environment, or that quietness cab not necessarily always match less “loud” acoustic environments. Herranz-Pascual and colleagues [ 12 ] indeed suggest that lively and vibrant urban soundscapes may also enhance people’s restoration. Aletta and Kang [ 13 ] propose a model to predict urban “vibrancy” using a soundscape approach. Perceived vibrancy can be predicted by a set of (psycho)acoustic parameters, the number of visible people on site, and the presence of music in the auditory scene. Music is indeed a key component of modern urban soundscapes: Whether designed or not, it has the potential to enhance the social experience of a place. Steele and colleagues [ 14 ] carried out an interventional study with an unsupervised installation in a public pocket park allowing users to play audio content from personal devices over publicly provided speakers and they found out that the soundscape was experienced as more pleasant for both users and non-users, and the calmness and appropriateness of the place were not a ff ected. Xiao and Hilton [ 15 ] investigate the factors influencing sound environments perception in relation to “square dancing”, a growing social phenomenon in many Chinese cities. A better understanding of contextual factors and aspects related to the interactions between people and places is required to characterize soundscapes holistically, as pointed out by Hermida and colleagues [ 16 ] in their case studies in Lisbon and Bogot á . For this purpose, it is certainly useful to review the corpus of literature looking at the positive e ff ects that soundscapes and environmental sounds more generally can have on people’s quality of life and well-being [17,18]. 3. Supportive Indoor Soundscapes—A Perceptual Perspective on Building and Room Acoustics The quality of outdoor acoustic environments is, of course, a mainstream dimension in the narrative of soundscape studies. However, considering that people spend the vast majority of their time in indoor environments, addressing the acoustic quality of such spaces is of paramount importance. It is, therefore, right to question how we expect buildings to “sound like” in order to promote supportive indoor soundscapes. While the acoustics in buildings has typically been dealing with sound insulation and room acoustics performances, a new perceptual perspective on the topic is gradually finding its way in. Taghipour et al. [ 19 ] look at how di ff erent building facades are likely to a ff ect the perceived acoustic quality of inner yards of residential complexes. Di Blasio and colleagues [ 20 ] focus on the overall comfort and performance of open-plan o ffi ce workers when a ff ected by undue noise coming from irrelevant speech. Similarly, looking at cognitive performance, Shu and Ma [ 21 ] carry out a 2 Int. J. Environ. Res. Public Health 2019 , 16 , 4988 study to explore the restorative e ff ects of di ff erent soundscapes on children’s sustained attention and short-term memory. Overall, the works published in this special issue reflect an active and engaged research community, which is exploring the connections between human well-being and the acoustic quality of the built environment from a broad range of methodologies and perspectives in terms of quietness and other dimensions. This is promising, as more e ff orts are required to address the challenges we face in promoting positive acoustic environments beyond noise control and acoustically “sanitized” spaces. Author Contributions: Conceptualization, F.A. and J.K.; methodology, F.A. and J.K.; writing—original draft preparation, F.A.; writing—review and editing, F.A. and J.K.; funding acquisition, J.K. Funding: This work was funded through the European Research Council (ERC) Advanced Grant (No. 740696) on “Soundscape Indices” (SSID). Acknowledgments: The Editors would like to thank all authors for their submissions and all reviewers for their thorough work on the manuscripts. Furthermore, the Editors are grateful to all IJERPH Editorial sta ff , in particular to Lin Li and Florence Wang for their professionalism and patient support throughout this process. Conflicts of Interest: The Editors declare no conflict of interest. References 1. World Health Organization. Environmental Noise Guidelines for the European Region ; WHO Regional O ffi ce for Europe: Copenhagen, Denmark, 2018. 2. European Parliament and Council. Directive 2002 / 49 / EC Relating to the Assessment and Management of Environmental Noise ; Publications O ffi ce of the European Union: Brussels, Bergium, 2002. 3. Kang, J.; Aletta, F.; Gjestland, T.T.; Brown, L.A.; Botteldooren, D.; Schulte-Fortkamp, B.; Lavia, L. Ten questions on the soundscapes of the built environment. Build. Environ. 2016 , 108 , 284–294. [CrossRef] 4. Kang, J. Urban. Sound Environment ; Taylor Francis incorporating Spon: London, UK, 2007. 5. Kang, J.; Schulte-Fortkamp, B. (Eds.) Soundscape and the Built Environment ; CRC Press: Boca Raton, FL, USA, 2015. 6. Dzhambov, A.M.; Markevych, I.; Tilov, B.; Arabadzhiev, Z.; Stoyanov, D.; Gatseva, P.; Dimitrova, D.D. Lower Noise Annoyance Associated with GIS-Derived Greenspace: Pathways through Perceived Greenspace and Residential Noise. Int. J. Environ. Res. Public Health 2018 , 15 , 1533. [CrossRef] [PubMed] 7. Hedblom, M.; Gunnarsson, B.; Schaefer, M.; Knez, I.; Thorsson, P.; Lundström, J.N. Sounds of Nature in the City: No Evidence of Bird Song Improving Stress Recovery. Int. J. Environ. Res. Public Health 2019 , 16 , 1390. [CrossRef] [PubMed] 8. Payne, S.R.; Bruce, N. Exploring the Relationship between Urban Quiet Areas and Perceived Restorative Benefits. Int. J. Environ. Res. Public Health 2019 , 16 , 1611. [CrossRef] [PubMed] 9. Zhang, S.; Zhao, X.; Zenz, Z.; Qiu, X. The Influence of Audio-Visual Interactions on Psychological Responses of Young People in Urban Green Areas: A Case Study in Two Parks in China. Int. J. Environ. Res. Public Health 2019 , 16 , 1845. [CrossRef] [PubMed] 10. Cerw é n, G. Listening to Japanese Gardens: An Autoethnographic Study on a Tool for Soundscape Design. Int. J. Environ. Res. Public Health 2019 , 16 , 4648. [CrossRef] 11. Cerw é n, G.; Mossberg, F. Implementation of Quiet Areas in Sweden. Int. J. Environ. Res. Public Health 2019 , 16 , 134. [CrossRef] 12. Herranz-Pascual, K.; Aspuru, I.; Iraurgi, I.; Santander, Á .; Eguiguren, J.L.; Garcia, I. Going beyond Quietness: Determining the Emotionally Restorative E ff ect of Acoustic Environments in Urban Open Public Spaces. Int. J. Environ. Res. Public Health 2019 , 16 , 1284. [CrossRef] [PubMed] 13. Aletta, F.; Kang, J. Towards an Urban Vibrancy Model: A Soundscape Approach. Int. J. Environ. Res. Public Health 2018 , 15 , 1712. [CrossRef] [PubMed] 14. Steele, D.; Bild, E.; Tarlao, C.; Guastavino, C. Soundtracking the Public Space: Outcomes of the Musikiosk Soundscape Intervention. Int. J. Environ. Res. Public Health 2019 , 16 , 1865. [CrossRef] [PubMed] 15. Xiao, J.; Hilton, A. An Investigation of Soundscape Factors Influencing Perceptions of Square Dancing in Urban Streets: A Case Study in a County Level City in China. Int. J. Environ. Res. Public Health 2019 , 16 , 840. [CrossRef] [PubMed] 3 Int. J. Environ. Res. Public Health 2019 , 16 , 4988 16. Hermida, L.; Pav ó n, I.; Lobo Soares, A.C.; Bento-Coelho, J.L. On the Person-Place Interaction and Its Relationship with the Responses / Outcomes of Listeners of Urban Soundscape (Compared Cases of Lisbon and Bogot á ): Contextual and Semiotic Aspects. Int. J. Environ. Res. Public Health 2019 , 16 , 551. [CrossRef] [PubMed] 17. Aletta, F.; Oberman, T.; Kang, J. Associations between Positive Health-Related E ff ects and Soundscapes Perceptual Constructs: A Systematic Review. Int. J. Environ. Res. Public Health 2018 , 15 , 2392. [CrossRef] [PubMed] 18. Erfanian, M.; Mitchell, A.J.; Kang, J.; Aletta, F. The Psychophysiological Implications of Soundscape: A Systematic Review of Empirical Literature and a Research Agenda. Int. J. Environ. Res. Public Health 2019 , 16 , 3533. [CrossRef] [PubMed] 19. Taghipour, A.; Sievers, T.; Eggenschwiler, K. Acoustic Comfort in Virtual Inner Yards with Various Building Facades. Int. J. Environ. Res. Public Health 2019 , 16 , 249. [CrossRef] [PubMed] 20. Di Blasio, S.; Shtrepi, L.; Puglisi, G.E.; Astolfi, A. A Cross-Sectional Survey on the Impact of Irrelevant Speech Noise on Annoyance, Mental Health and Well-being, Performance and Occupants’ Behavior in Shared and Open-Plan O ffi ces. Int. J. Environ. Res. Public Health 2019 , 16 , 280. [CrossRef] [PubMed] 21. Shu, S.; Ma, H. Restorative E ff ects of Classroom Soundscapes on Children’s Cognitive Performance. Int. J. Environ. Res. Public Health 2019 , 16 , 293. [CrossRef] [PubMed] © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http: // creativecommons.org / licenses / by / 4.0 / ). 4 International Journal of Environmental Research and Public Health Article Lower Noise Annoyance Associated with GIS-Derived Greenspace: Pathways through Perceived Greenspace and Residential Noise Angel M. Dzhambov 1, * ID , Iana Markevych 2,3 , Boris Tilov 4 , Zlatoslav Arabadzhiev 5 , Drozdstoj Stoyanov 5 , Penka Gatseva 1 and Donka D. Dimitrova 6 1 Department of Hygiene and Ecomedicine, Faculty of Public Health, Medical University of Plovdiv, 4002 Plovdiv, Bulgaria; gatseva_p@mail.bg 2 Institute and Clinic for Occupational, Social and Environmental Medicine, University Hospital, LMU Munich, 80336 Munich, Germany; iana.markevych@helmholtz-muenchen.de 3 Institute of Epidemiology, Helmholtz Zentrum München—German Research Center for Environmental Health, 85764 Neuherberg, Germany 4 Medical College, Medical University of Plovdiv, 4000 Plovdiv, Bulgaria; btilov@abv.bg 5 Department of Psychiatry and Medical Psychology, Faculty of Medicine, Medical University of Plovdiv, 4002 Plovdiv, Bulgaria; zlatolini@gmail.com (Z.A.); stojanovpisevski@gmail.com (D.S.) 6 Department of Health Management and Healthcare Economics, Faculty of Public Health, Medical University of Plovdiv, 4002 Plovdiv, Bulgaria; donka_d@hotmail.com * Correspondence: angelleloti@gmail.com; Tel.: +359-897-950-802 Received: 1 July 2018; Accepted: 19 July 2018; Published: 19 July 2018 Abstract: Growing amounts of evidence support an association between self-reported greenspace near the home and lower noise annoyance; however, objectively defined greenspace has rarely been considered. In the present study, we tested the association between objective measures of greenspace and noise annoyance, with a focus on underpinning pathways through noise level and perceived greenspace. We sampled 720 students aged 18 to 35 years from the city of Plovdiv, Bulgaria. Objective greenspace was defined by several Geographic Information System (GIS)-derived metrics: Normalized Difference Vegetation Index (NDVI), tree cover density, percentage of green space in circular buffers of 100, 300 and 500 m, and the Euclidean distance to the nearest structured green space. Perceived greenspace was defined by the mean of responses to five items asking about its quantity, accessibility, visibility, usage, and quality. We assessed noise annoyance due to transportation and other neighborhood noise sources and daytime noise level (L day ) at the residence. Tests of the parallel mediation models showed that higher NDVI and percentage of green space in all buffers were associated with lower noise annoyance, whereas for higher tree cover this association was observed only in the 100 m buffer zone. In addition, the effects of NDVI and percentage of green space were mediated by higher perceived greenspace and lower L day . In the case of tree cover, only perceived greenspace was a mediator. Our findings suggest that the potential for greenspace to reduce noise annoyance extends beyond noise abatement. Applying a combination of GIS-derived and perceptual measures should enable researchers to better tap individuals’ experience of residential greenspace and noise. Keywords: green space; greenness; noise exposure; noise perception; soundscape 1. Introduction Residential noise is a ubiquitous environmental stressor that has been linked to a wide range of non-auditory health outcomes, including cardiometabolic diseases, adverse pregnancy outcomes, Int. J. Environ. Res. Public Health 2018 , 15 , 1533; doi:10.3390/ijerph15071533 www.mdpi.com/journal/ijerph 5 Int. J. Environ. Res. Public Health 2018 , 15 , 1533 and mental ill-health, to name a few [ 1 ]. Reduction of noise annoyance, which serves as a proxy for noise exposure and is itself detrimental to health, is one of the possible explanations why people residing in green neighborhoods have better health compared to their counterparts [ 2 ]. Greener neighborhoods have less artificial noise-emitting sources [ 2 ]; moreover, vegetation can reduce noise levels by physical disruption of sound waves propagated from the source to the receiver [ 3 ]. Nevertheless, existing elements in the urban green network, such as street trees, have limited capacity as noise barriers and may even increase pedestrian noise exposure, for instance, in street canyons, where tree canopies can reflect sound waves to the level of pedestrian’s ears [ 4 , 5 ]. Additionally, a large proportion of the variation in residents’ annoyance is caused by non-acoustic factors [ 1 , 6 ]. Therefore, changes in annoyance may be disproportionate to the actual reduction in noise level [1,4]. Accumulating evidence is showing that greenspace can reduce traffic-related annoyance via psychological mechanisms, including visual screening of the noise source, increased restorative quality of the residential environment, and masking of unwanted noise with pleasant nature sounds [ 4 ]. Additionally, green spaces near the home may strengthen residents’ feeling of control over their acoustic environment by allowing respite from traffic noise, thereby diminishing their noise annoyance [ 7 ]. Investigating the latter hypothesis, Riedel et al. observed an indirect effect of near-dwelling greenspace on noise annoyance through perceived noise control [ 7 ]. Residing in quiet green areas has been associated with higher health-related quality of life, and that could be due in part to the “quietness” characteristic that people ascribe to greener areas [ 8 ]. Even if green spaces are not actively visited, the very knowledge that the residential environment has such natural areas may enhance residential satisfaction and possibly improve noise perception [ 4 , 9 ]. These psychological effects could explain findings that living in a neighborhood with more trees seemed to buffer the negative effect of traffic noise on mental health [10]. Most previous studies on psychological buffering of noise annoyance employed self-reported measures of greenspace and mostly considered only annoyance due to road traffic noise [ 11 ]. Van Renterghem and Botteldooren’s study was one of the prominent exceptions, as they examined the effect of both objectively-measured and self-reported green view from home on general and traffic noise annoyance [ 12 ]. Another such example is the study by Riedel et al. who used land use maps to assess residential greenspace [ 7 ]. Spatial and perceived indices should be used together to better understand the effect of greenspace on health, including noise perception [ 2 ]. Metrics derived from Geographic Information Systems (GIS) would be useful when investigating the indirect path linking objective greenspace to noise annoyance through reduced noise levels, whereas self-reports would better highlight residents’ greenspace experience [ 2 ]. Another issue that should be considered is that both objective and perceived greenspace can be defined differently, and these metrics may be related differently to noise annoyance [ 13 ]. Consistent with this idea, a meta-analysis showed lower odds of high noise annoyance in people who had a green view from their home, whereas the overall greenness (i.e., vegetation degree) in the neighborhood did not reduce noise annoyance [ 11 ]. Another study examined the effect of different objective greenspace measures and observed a beneficial effect only for tree cover density in the 100 m buffer zone, but not for overall greenness [14]. To our knowledge, no previous study has investigated whether the effect of greenspace on noise annoyance is mediated by a reduction in noise level and higher perceived greenspace. Such knowledge could help us understand whether relying on objective measures in urban planning and forestry is sufficient to gain insight into these human-environment interactions. In the present study, we examined the association between objectively-measured greenspace and noise annoyance, with a focus on underpinning pathways through residential noise and perceived greenspace in the neighborhood. We tested the model shown in Figure 1 using different measures of greenspace. 6 Int. J. Environ. Res. Public Health 2018 , 15 , 1533 Figure 1. Conceptual diagram showing theoretically-indicated pathways linking Geographic Information System (GIS)-derived greenspace to noise annoyance. (Positive associations are marked with “+”, and negative associations, with “ − ”.) 2. Materials and Methods 2.1. Study Design and Sampling We used data from a cross-sectional survey conducted between October and November 2017 in students from the Medical University of Plovdiv, Bulgaria. Plovdiv is the second largest city in the country with a population of around 342,000 and a territory of around 102 km 2 . Public green spaces in the city account for 75.3% (381.5 ha) of all green areas, which is 11.2 m 2 per capita. The distribution of these green spaces is scattered, and in some parts of Plovdiv, there are less than 4 m 2 of green space per capita [ 15 ]. At the same time, the 2016 noise mapping campaign indicated that 77% of residents were exposed to day-evening-night road traffic noise above 60 dB(A) [16]. The aim of our study was to investigate the mental health-supporting effects of residential greenspace. To be included in the study, students had to be aged from 18 to 35 years and reside in Plovdiv or its surroundings for the last six months. We targeted potential participants with different ethnic and cultural backgrounds, ages, and program enrollments to ensure sufficient variation in the data. During a class or lecture, members of the research group advertised the study, informing the students about its general objectives, and asked them to complete a questionnaire. In addition to questions on sociodemographic factors and residential environment, participants were asked to report their current living address for subsequent assignment of geographic variables. The study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the Ethics Committee of the Medical University of Plovdiv (1/02.02.2017). All participants provided their informed consent for inclusion before they participated in the study. No incentives were offered. A more detailed account of the survey design has been reported previously [17]. Of the 1000 students invited, 823 (82%) agreed to participate. Residential addresses were manually converted into geocodes with the help of Google maps. Of the 823 students, 720 provided sufficient data, including residential addresses, to be included in the study. The majority of them (n = 642, 89.2%) lived in the city of Plovdiv (Figure 2). 7 Int. J. Environ. Res. Public Health 2018 , 15 , 1533 Figure 2. Map of residential addresses superimposed over Normalized Difference Vegetation Index (NDVI) geographic layer. 2.2. Greenspace Based on previous evidence that different types and properties of greenspace may have different potential to reduce noise annoyance [ 14 ], objective greenspace was defined by several GIS-derived metrics: Normalized Difference Vegetation Index (NDVI), percentage of green space, tree cover density, and the Euclidean distance to the nearest structured green space. NDVI [ 18 ] served as a measure of surrounding greenness. NDVI is commonly used as a proxy for overall vegetation level and ranges from − 1 to +1, with positive values close to 1 indicating dense vegetation [ 19 ]. The NDVI equation is based on the difference in surface reflectance in two vegetation-informative wavelengths: visible red and near infrared light. For these calculations, we used six Sentinel 2 MultiSpectral Instrument satellite images with a resolution of 10 × 10 m for the needed bands, obtained on 16 and 18 October 2017. Because bluespace is thought to share the capacity of greenspace to improve noise perception, we wanted to differentiate the effect of greenspace from the effect of bluespace. So, we removed all water pixels from the satellite images prior to assigning NDVI to the geocodes by using the Open Street Maps (OSM) water layer [ 20 ]. Tree cover density was calculated based on the Tree Cover Density 2012 map developed by the European Environmental Agency at a resolution of 20 × 20 m . Percentage of structured green space was calculated from the Urban Atlas 2012 land use map. Mean NDVI, mean tree cover density, and percentage of structured green space were abstracted in circular buffers of 100, 300 and 500 m around the residence [ 17 , 20 ]. Euclidean distance to the edge of the nearest structured urban green space was calculated based on the OSM data, and included parks, allotments, and recreation grounds. Geographic data management and calculations were performed using ArcGIS 10.3–10.4 Geographical Information System (GIS) (ESRI, Redlands, CA, USA). Perceived greenspace was assessed with five items asking respondents about different aspects of their experience of, and interaction with, greenspace in their neighborhood [ 17 ]. Specifically, we considered the overall perceived neighborhood greenness, visible greenery from home, accessibility to the nearest structured green space, time spent in green space, and quality of green space. Items could be answered on a 6-point scale. The score for this measure was the mean of item responses, with higher values indicating greater perceived greenspace in the living environment. Cronbach’s alpha for this scale was 0.81. 2.3. Noise Level Noise level was calculated by a combination of measurements and modelling at each participant’s address with the help of a land use regression (LUR) model. The LUR was developed specifically for this study and was based on noise measurements recorded by the Regional Health Inspection at 40 locations in Plovdiv in 2016. Measurements were conducted over a 12-hour period from 7:00 a.m. to 7:00 p.m. (L day ) according to ISO 1996-2:1987. Predictor variables derived from GIS were considered in the regression equation, following a supervised forward stepwise selection procedure, 8 Int. J. Environ. Res. Public Health 2018 , 15 , 1533 as described by Aguilera et al. [ 21 ]. The final LUR had an adjusted correlation coefficient (R 2 ) of 0.72 and leave-one-out cross validation R 2 of 0.65. More details about model development have been reported previously [17]. 2.4. Noise Annoyance Noise annoyance was calculated by the mean of responses to two items. Items asked about annoyance/disturbance by traffic noise and other neighborhood noise sources included: “How much does road traffic noise bother, disturb, or annoy you?” and “How much does noise from neighbors/construction/recreational establishments bother, disturb, or annoy you?”. The response scale ranged from “0 = Not at all” to “4 = Extremely” and followed the recommendation by the International Commission on Biological Effects of Noise [ 22 ]. The correlation between the two items was strong enough to justify their combination into one scale, r = 0.47 ( p < 0.001). The mean of the responses served as a measure of noise annoyance in the living environment. 2.5. Confounders We also considered several potential confounding factors, including participants’ age, sex, ethnicity, duration of residence at the address, and average time spent at home per day. Individual-level economic status was assessed by a single item: “Having in mind your monthly income, how easy is it for you to “make ends meet”, meet your expenses without depriving yourself?”. Responses could range from “0 = Very difficult” to “5 = Very easy”. Recently experienced stressful life events were assessed with the item “Have you lately experienced a stressful life event, such as death/illness of a relative, separation from a loved one, or being fired?”. The geocodes were used to assess population density in a 500 m buffer zone around the address from the 2011 Census population grid of Bulgaria and whether participants lived in Plovdiv or any other settlement nearby. We also considered the presence of b