:: Biblioteca Digital de Ecopsicologia (BDE)

EFFECTS OF NATURE AND CITY SOUNDS ON PHYSIOLOGICAL AND PSYCHOLOGICAL VARIABLES IN COLLEGE STUDENTS

EFFECTS OF NATURE AND CITY SOUNDS ON PHYSIOLOGICAL AND

PSYCHOLOGICAL VARIABLES IN COLLEGE STUDENTS

Domenic DiPietro

A Thesis

Submitted to the Graduate College of Bowling Green

State University in partial fulfillment of

the requirements for the degree of

MASTER OF SCIENCE

December 2020

Committee:

Maria G. Bidart, Advisor

Verner Bingman

Daniel Wiegmann

Domenic DiPietro

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ABSTRACT

M. Gabriela Bidart, Advisor

With an increasing human population, there are more densely-populated urban cities.

Although this supports our gregarious lifestyles, it consequentially inhibits our contact with

nature. This study focuses on the effects of different types of sounds on physiological and

psychological variables in college students. Specifically, nature sounds (a mixture of birdsongs

and water sounds) and man-made, city sounds (a mixture of traffic, construction, and siren type

of sounds) were evaluated for their potential effects on heart rate, breathing rate, and emotional

states using the Positive and Negative Affect Schedule (PANAS) questionnaire. Participants

included 20 female students ranging from 18-28 years old. Using a within-subject design, each

participant was assigned to listen to both a 7-minute segment of nature sounds and a 7-minute

segment of city sounds (order of type of sounds was randomized). Sound volume was set at

approximately 70 dB (conversational volume) through their own device and headphones. All

dependent variables were recorded manually before the sound intervention and after each of the

two sound treatments. Since this study was performed throughout the COVID-19 global

pandemic, each experimental trial was performed remotely over a WebEx virtual conference, and

variables were self-recorded by each of the participants. Results showed that a seven-minute

segment of nature sounds significantly decreased respiration rate (P < 0.0001) and negative

affect schedule score (P < 0.0001) when compared against a seven-minute segment of urban

sounds. Additionally, a survey prior to sound treatments revealed that participants had a higher

preference for nature than for urban environments (P < 0.0001). Future research would help

further understand variability in physiological responses, as well as human preferences for

different types of sounds.

I dedicate this thesis to my parents, who have given me unconditional love, support, and the

belief that we are all life-long learners, regardless of our endeavors.

ACKNOWLEDGMENTS

I cannot extend enough thanks to my advisor, Dr. M. Gabriela Bidart, for her unending

support and patience throughout my graduate pursuits. Her patience through our hurdles,

solutions to common problems, knowledge in the field of science, and unending aid have been

invaluable through both my academic and social lives. I am fortunate to have her as a mentor as

she has helped confirm that I love working as a scientist.

I would also like to thank my committee members, Dr. Daniel Wiegmann and Dr. Verner

Bingman for their inputs, advice, support, and adaptability throughout my graduate experience.

I’d also like to thank my lab mates Claire Thelen, Lauren Greenwell, and Kelsey Dietrich for

their feedback, opinions, and tremendous help with brainstorming ideas and broadening my

horizons.

A big thank you to my friends and family who have helped keep me grounded with

motivation, fellowship, and the subtle reminder of the importance in quality of life. I’d like to

specifically mention Isabella DiPietro, Liam DiPietro, Michael Sheehan, and Michael March for

my special ties to them. Daniel Walton gets thank you for introducing me to Ableton Live and

its cross compatibility with files. Finally, a special thanks to Abigail Jarosz for reminding me to

eat, get some sleep, being a guinea pig for trials, and enjoying my quarks in lab and life.

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TABLE OF CONTENTS

Page

INTRODUCTION ............................................................................................................... 1

MATERIALS AND METHODS ......................................................................................... 5

Participants and Recruitment .................................................................................... 5

Experimental Sounds ................................................................................................ 6

Experimental Design ................................................................................................ 7

Statistical Analysis ................................................................................................... 9

RESULTS......…….................................................................................................................. . 10

DISCUSSION......……............................................................................................................. 12

LITERATURE CITED ........................................................................................................ 18

APPENDIX A. PARTICIPANT INFORMED CONSENT ................................................... 25

APPENDIX B. BASELINE QUESTIONNAIRE ................................................................. 27

APPENDIX C. POSITIVE AND NEGATIVE AFFECT SCHEDULE (PANAS)

QUESTIONNAIRE......…….................................................................................................... 28

APPENDIX D. PARTICIPANT INSTRUCTIONS FOR ONLINE LOUDNESS METER ... 29

APPENDIX E. FIGURES...................................................................................................... .. 30

APPENDIX F. TABLES.…..................................................................................................... 33

INTRODUCTION

There has been a growing interest in enhancing our relationship with nature around the

world in the past few decades. Originating almost 40 years ago in Japan, the practice of Shinrin-

yoku, translating to forest-air bathing, relates to the experience of individuals immersing into a

natural environment (Hansen et al. 2017). This activity is broadly thought to increase our overall

wellness (Park et al. 2010). Forest bathing is still a relatively new research topic, and the

scientific and medical communities are just beginning to ascertain how to implement shinrin-

yoku as a natural, wellness medicinal approach (Largo-Wight et al. 2016).

There are a few challenges related to the modern world that may interfere with humans’

potential for reconnecting with nature. Access to natural areas with plants and wildlife may be

difficult to find; especially, for individuals living in metropolitan areas (Hoffimann et al. 2017).

According to the United States 2010 Census, 80.7% of the population lives in an urban area or

cluster (“Urban Areas Facts” 2018). When compared against each other, individuals in a forest

setting have significantly lower risks of cardiovascular disease than those in a city environment

(Hassan et al. 2018). Among recent studies, rapidly urbanizing areas are changing the selective

pressures of animal populations around them (Tüzün et al. 2017). Plants also change in

responses to the presence and abundance of pollinators in a certain area (Veits et al. 2019). If

availability of parks and wildlife is scarce, the next best option would be to create more natural

areas with gardens in outdoor settings, which can still boost activity levels and wellness for

humans (Wolf 2008). An abundance of outdoor plants attracts positive attention, and can also

increase property values, especially in urban areas with dense populations and construction sites

(Wolch et al. 2014). City designers and organizers may avoid incorporating too many trees in an

urban environment due to potential risks related to branches falling or high maintenance,

especially if trees are closer to the road or electrical poles (Dixon and Wolf, 2007). However,

completely removing trees and plants from cities can have negative effects on human health

(Grinde and Grindal, 2009). The lack of green landscape can cascade along with other problems,

such as financial or personal struggles, which can all influence stress levels in humans (Wolch et.

al., 2014). Those who are immersed in a green environment may feel less stressed than those

living in a completely urban landscape (Mitchell and Popham 2008). From a commissioner’s

standpoint, there are still ways to receive the benefits of nature without sacrificing roads and

economic space. Strategically placing plants in urban communities may induce a greater

parasympathetic nervous system activity, and thus, relaxation, while decreasing sympathetic

nervous system activity associated to stress responses (Park et al. 2010).

From a fiscal point of view, having plants in a workplace can boost creativity and

cognitive function (Mangone et al. 2017). This general nature exposure can subconsciously

influence daily decisions as fundamental as where people would want to shop (Wolf 2007).

Findings generally show that stores with a more “biophilic” design yield greater satisfactory

ratings by consumers (Joye et al. 2010). This connects with other findings such as how tree

canopy area is significantly correlated to perceived general health (Maas et al. 2006). With such

a positive influence of nature exposure, it may be a good effort to amend our seclusion from

green spaces.

Positive effects of nature on humans is induced by sensory signals. A nice view, bird

songs, water sounds, the scent of plants and flowers can stimulate relaxation. Although full

immersion in nature (with all senses) would be best, individuals can still reap benefits from

artificial and partial exposure to nature (Wackermannová et al. 2016). Sounds that relax us can

be associated with natural environments that potentially maximize the effectiveness of auditory

stimuli. Videos and images of natural environments are known to ease a stressed state (Ulrich et

al. 2008). Additionally, nature sounds and scents may provide just as many benefits as visual

stimuli (Franco et al. 2017). Nature sounds may be similar than effects of music on humans.

Some studies show that music can lessen the impacts of a stressful event, (Thoma et al. 2013).

Those suffering from depression and other psychological conditions can be calmed by music

therapy (Ray and Götell, 2018). These auditory relaxers may have a wide range of variability as

bias of musical preference could skew results from subject to subject (Gruhlke et al. 2017). The

benefit of certain sounds, such as natural running water, may even be more beneficial than

listening to soft music, and could be linked to human evolution in natural environments (Thoma

et al. 2018). In a society where urbanization is expanding, maximizing the integration of urban

areas with nature can be of major psychological benefit (van den Berg et al. 2007). These

patterns suggest that negative effects of daily stressors, in the absence of direct access to nature,

may be alleviated by simply listening to recordings of nature sounds, and/or videos incorporating

both auditory and visual stimuli.

Traffic, for example, can be a seemingly unavoidable daily encounter for populations in

metropolitan areas. The noises alone from traffic can insinuate stress (Franek et al. 2017).

Individuals walking with the sound of traffic walk significantly faster than in an alternate route

of equal distance with forest birdsong (Franek et al. 2017). After applied auditory stressors,

nature sounds can quickly help individuals to relax (Alvarsson et al. 2010). In addition, nature

sounds played before a stressful experience; like surgery, can significantly reduce patient anxiety

(Amiri et al. 2017). With an array of situations in which natural sounds can help, we may

wonder why we don’t see “more nature” in our urbanized environments. With an ever-

increasing demand for urbanization, it can be very difficult for some individuals to have the

opportunity to be immersed with nature (Hoffimann et al. 2017). For these individuals, listening

to nature sounds could be a potential way to gain some of the benefits of nature on health and

cognition (Hedger et al. 2019). A recent study has showed that nature sounds can significantly

reduce physiological stress after just seven minutes of exposure (Largo-Wight et al. 2016).

The main goal of my research was aimed at evaluating the effects of different types of sounds

(i.e., nature and man-made sounds) on physiological and psychological responses of female

college students. With the challenges that arose with the COVID-19 pandemic, the original

research plans had to be modified to be completed remotely. I evaluated the effect of (i) a

mixture of nature sounds including water sounds and birdsongs, and (ii) a mixture of urban

sounds including heavy traffic and sirens) remotely, using videoconference meetings as trials.

While it can be predicted that a mixture of nature sounds can be perceived as more relaxing than

a mixture of urban sounds, it can be expected there could be a range of variability due to

individual preferences or differences in the perception of the distinct sounds from subject to

subject. Among our rapidly urbanizing population, some bird species are changing their song

repertoires, which may differ from those present at the times of our human ancestors (Deonizak

& Osiejuk, 2019). Additionally, acute lethargic, anxiety, or depressive-like symptoms are

reported in some individuals among our coronavirus epidemic (Wang et al. 2020). This research

study will provide important information regarding how different environments (i.e., nature

versus urban environments) may affect physiological and psychological responses of human

subjects, which could be related to stress or relaxation. This information could be further applied

to boosting cognitive performance (Van Hedger et al. 2019), and general wellness (Thoma et al.

2018) while, for example, creating a working from home environment.

MATERIALS AND METHODS

Participants and Recruitment

The research population for this study included 20 female university students from 18 to

28 years of age. Upon completion of training and proposal submission, the Bowling Green State

University Institutional Review Board (IRB) approved this project #1502803. Recruitment

included approved text for emails and university announcements, in addition to giving

information through BGSU online classes via canvas course shells. Along with recruitment text,

each participant received PDF of the IRB stamped consent form (Appendix A) for a full

description of minimal risk, confidentiality, and the voluntary nature of the study. If the

contacted individuals expressed interest, they were allowed to select a meeting time on any

weekday at 6, 7, or 8 pm. Upon confirmation of a time for a WebEx meeting, each participant

was emailed the files they would need for the study. These files included the sound mixes, a

consent form as a Word document that each participant could sign, and a template to insert

physiological and psychological measurements taken by the participant during the study. In

addition to sending all these files to the participants, the researcher directly guided them through

each recorded activity via WebEx teleconference meetings.

Twenty-four hours before each trial, the participants were asked to avoid eating foods

with excessive amounts of carbohydrates, as well as consuming a regular amount of caffeine in

accordance to their individual, daily routine. An initial questionnaire (Appendix B) was

completed after the consent form to ensure there have been no abnormal changes in diet, rest, or

physical activity that could alter physiological or psychological measurements.

Experimental Sounds

All sounds used were specifically collated for this study. Seven individual sound

segments were acquired through “Freesound.org.” Three sound segments were used for the mix

of nature sounds and four sound segments were used for the mix of urban sounds. Nature sounds

consisted of birdsong and running stream water (Appendix D), while urban sounds included

traffic, construction, and sirens (Appendix D). Six out of the seven sounds are under the

“Creative Commons 0,” without copyright license, as the creators have included them on

freesound.org as public domain for free and open use. The last sound fits under the attribution

category of “Creative Commons Use.” Under this license, credit is given to sound creator,

Klankbeeld (https://freesound.org/people/klankbeeld/) for the production of one of the sounds

used in the urban sound mix for this study. A link to the attribution and license is required and

included herein (https://creativecommons.org/licenses/by/3.0/).

Each of the six sounds were normalized using the free software, Praat, to equalize them

to the same average volume of 70 dB. These normalized files were then assembled together

using the standard version of sound software Ableton Live 10 using a MacBook Pro Model

A1502 (Apple, Cupertino, CA, USA). In the sound software, volumes were slightly modified,

each segment was repeated, and the collection of each of the segments was grouped to be

exported as an mp3 file to be sent to the participants. With the restriction of file size capabilities

in an email, mp3 files were used instead of wav files. Each sound segment was set to 7 minutes

following methods by Largo-Wright et al. (2016), since they found this amount of exposure to be

effective to significantly reduce physiological stress in a similar setting (after a “brief nature

sound intervention”). Both of the urban and nature sound files were exported so that they had

the same average and peak dB values. This ensures that when they were sent to each participant

as separate mp3 files, the urban and nature sounds were heard at the same volume.

Experimental Design

A within-subject approach was used to evaluate the effects of nature and man-made city

sounds on physiological and psychological measurements in human subjects. This study was

completed during the COVID-19 pandemic, so all contact with the participants was virtual,

including classroom recruitment through Canvas course shells, email communication, and

videoconference meetings via WebEx. Each participant was only asked to participate in a single,

one-hour meeting that was used for instruction, listening to the sounds, and self-recording of

their heart rate and breathing rate, as well as completing the Positive and Negative Affects

Schedule (PANAS) survey after listening to the nature and city sounds. In addition, two

questions related to perception of the two environments (perceived comfort) were responded by

participants before the sound trials.

Following a within-subject design, each participant listened to both the mixture of nature

sounds and the mixture of city sounds. For counterbalancing, the order was randomly assigned

using a random integer generator within a TI-Nspire CX CAS (Texas Instruments, Dallas, TX,

USA). In each trial, there was a 10-minute period between listening to sounds to allow for the

participants’ vital signs to return to baseline.

Dependent variables were recorded at the beginning of the study, as a baseline, and then

immediately, after each of the 7-minute sound segments. Heart rate was recorded by the carotid

pulse. The researcher instructed subjects to manually record their heart rate by placing their

middle and index fingers to the side of their windpipe for 15-seconds. Time was kept by the

experimenter, giving signals to start and stop counting. Similarly, each participant was asked to

count the number of breaths they took in 60-seconds. For this purpose, participants were asked

to count the number of times that they inhaled (i.e., every time the chest/abdomen rises). When

both physiological vitals were successfully recorded, each participant completed the PANAS

survey. The PANAS is split into the positive affect score (PAS) and the negative affect score

(NAS). The PAS has ten emotions associated with positive mood are given a score from one to

five in order to evaluate each participant’s mood state. A sum of each of the ten positive

emotions then conveys the PAS score with a higher score signifying a more positive mood.

Similarly, the NAS also has ten emotions in which participants record a score from one to five on

relative feeling. The sum of these ten scores results in the NAS score in which higher score

signifies a more negative mood. The visual template participants used is shown in Appendix C.

In addition, before the sound trials started, as part of some general questions (Appendix B), the

participants answered two questions related to perception of the two types of sounds using a

Likert scale of 1-7 (1 = very stressful and 7 = very relaxing). To achieve a comfortable volume,

a free online loudness meter, created by Youlean, was used. Each subject was asked to use

headphones to mitigate auditory distraction from their surrounding environment. Prior to

listening to the sounds, participants were asked to follow these directions to achieve a playing

volume that would have no risk to damaging their hearing:

1. On a smartphone or tablet device separate from the one you’re using for your sounds, go

to the following url:

https://youlean.co/online-loudness-meter/

2. Allow the website to use your device’s microphone

3. Open the NatureSounds.mp3 file and play it from the device you’ll be playing the sounds

from through your headphones

4. Hold your headphones around the speaker using the Youlean loudness meter

5. Adjust your sound volume on your device so that the average is approximately 70 dB

Each time you change the volume, click/touch the “X” on the loudness meter.

This restarts the meter so you get a new average

6. It’s crucial that you don’t change your computer’s volume for the rest of the study.

An average of 70 dB was chosen as it resembles conversational volume. Peak volumes in both

mixes did not pass 87 dB. At 90 dB, potential hearing damage could occur only after 8 hours of

continuous exposure, so all participants were completely safe throughout the study. While

listening to each of the sound segments, participants were asked to keep their eyes open, remain

in a seated and neutral position, and to concentrate on the sounds as best as they could.

Statistical Analysis

The data generated from this research project were statistically analyzed using SAS

Software. version 9.4 (SAS Institute, Cary, NC, USA). Analyses of Variance were conducted to

test for the effects of the sound treatments (i.e., nature and city sounds) and subjects on vital signs,

and PANAS scores. When assumptions of normality and heterogeneity of variance were not met,

data were rank-transformed. Pairwise comparisons among treatment means were performed using

Fisher’s Least Significant Difference tests when ANOVA models were significant (protected

LSD). In addition, a measure of perceived comfort with city and nature sounds before the sound

trials was analyzed using a Kruskal-Wallis test.

RESULTS

Results from this study provide evidence of how participants differentially responded to

nature and city sounds both psychologically and physiologically. Analyses of variance

(ANOVA) showed no significant effects of the sound treatments on heart rate (F2, 38 = 2.99; P =

0.0625) (Figure 1 a), but significant effects between subjects (F19, 38 = 25.59: P < 0.001).

There were, however, statistically significant effects of treatments and subjects on respiration

rate (Treatment: F2, 38 = 12.87; P < 0.0001; and Subject: F19, 38 = 6.06; P <0.0001). Multiple

comparisons among treatment means showed that respiration rates after listening to nature

sounds were significantly lower (by 23%) from those after the city sound intervention. Baseline

measurements were not statistically different than either of the two sound interventions (Figure 1

b).

Psychological measures of positive and negative affect schedule (PANAS) scores

differed after city and nature sounds. PANAS scores include positive affect scores (PAS) and

negative affect scores (NAS) (Table 1). The effect of sound treatments significantly influenced

total PAS (F2, 38 = 15.72; P < 0.0001). Comparisons of the means showed that listening to city

sounds induced a decrease in the mean total PAS of the participants, which was 23.4% lower

than baseline scores (Figure 2 a). However, mean PAS after nature sound intervention was not

significantly different from either of the other two groups. For total NAS, there was a significant

effect of sound treatment (F2, 38 = 24.84; P < 0.0001), but no significant results for subjects

(F19,38= 1.73; P < 0.0752). Pairwise comparisons revealed that mean total NAS after city and

after nature sounds were significantly different from each other and from baseline scores. Mean

total NAS of participants increased by 31.1% (from baseline) after listening to the city sounds,

while listening to the nature sounds yielded a 14.9% decrease in negative affect scores (Figure 2

b). The measure of “perceived comfort” with the two types of environments prior to the sound

trials was also statistically significantly different (F1, 19 = 52.22; P < 0.0001). As shown in

Figure 3, the average Likert scale perception of city sounds before the start of the sound trials

was 2.85 while the average perception of nature sounds was 6.25 indicating that nature sounds

were perceived as more “comforting” than city sounds.

DISCUSSION

Previous studies have evaluated the effects of human physiological and psychological

responses to the environment (Grinde & Patil, 2009; Beatley, 2011; Franco et al. 2017). Most of

these studies explored the effects of urban and natural environments in a fully immersive way, in

which the environments stimulate several senses simultaneously (e.g., sight, sound, and smell).

The present study focuses on auditory stimuli, which is processed initially through the primary

auditory cortex (A1), and these findings are the first to explore how humans react to urban and

natural auditory stimuli remotely, from a home rather than a lab setting. Results showed that

listening to pre-recorded nature sounds induced a significantly lower respiration rate (Figure 1 b)

and Negative Affect Score (NAS) (Figure 2 b) than city sounds. This outcome agreed with a

survey completed before the sound interventions in which participants showed a higher

(statistically significant) preference for nature over city sounds (Figure 3). As a whole, these

results suggest that humans still have a positive, innate connection to green spaces and natural

environments. Thus, reconnecting with nature can result in benefits to the mind and body,

especially for those living in densely-populated areas.

Overall, the experimental results suggest that the sounds of an urban area have different

effects on human psychology and physiology than the sounds of a natural environment. From

the two physiological variables measured (i.e., heart rate and respiration rate), heart rate, was the

only variable in this study that was not significantly influenced by the different sound

interventions (Figure 1 a). A previous study by Gee et al. (2019) also showed a lack in

significant changes in heart rate, but an improvement with anxiety and mood when participants

observed aquariums with live fish, plants, and water while in a laboratory setting. The lack of

significance results from this study could be primarily due to a large variability in heart rate

across participants (significant within-subject effects on heart rate). Individual measurements

ranged from a minimum of 56 bpm to a maximum of 136 bpm. In addition to variability, heart

rate naturally changes very rapidly, and although it was measured immediately after each sound

intervention, some of the participants struggled to quickly find their carotid pulse.

The other physiological variable measured for this study was respiration rate. Lower

respiration rates suggest activation of the parasympathetic nervous system (PNS), which is the

part of the autonomic nervous system (ANS) responsible for relaxation. This occurs through

vagal activity, as the vagus nerve is a major conduit between the lungs and the brain (Geus et al.

1994; Chang et al. 2015). In contrast, the sympathetic nervous system (SNS) is the part of the

ANS that is activated by stressful situations. Activation of the PNS alleviates negative effects of

stressors by reducing SNS activity, and thus, balancing ANS responses, which leads to

relaxation. Comparisons among treatment means in this study showed that mean respiration rate

after listening to a seven-minute segment of city sounds was significantly higher than the mean

respiration rate after listening to a seven-minute segment of nature sounds (Figure 1 b). The

respiration rate from this study is in accordance with similar studies by Fuertes et al. (2014) and

Kondo et al. (2018), as participants in green spaces recorded lower respiration rates and fewer

chronic health complications when compared to participants in urban environments. The

findings from this study suggest that individuals who are stressed in urban areas and don’t have

access to parks may benefit from listening to pre-recorded nature sounds to help activate their

PNS and drive relaxation responses.

As part of the peripheral nervous system, PNS and SNS also influence psychological

states as happy or relaxed moods are congruent to PNS activity. Contrarily, anxiety and

depressive feelings can be associated with a SNS stress response. For this study, psychological

state was measured using the Positive and Negative Affect Schedule (PANAS) questionnaire.

This questionnaire gives a list of emotions that, when scored, give a positive affect score (PAS)

and a negative affect score (NAS). In this study, PAS has a significant decrease from baseline

measurements after listening to the seven-minute segment of city sounds (Figure 2 b). This

result is in accordance with a study by Berman et al. (2012), in which the PANAS questionnaire

was used to discover an improvement in mood for participants in natural settings. For the results

of this study, multiple comparisons among means showed no significant differences in PAS

means between the after-nature sound intervention and the other two groups. The significant

decrease in PAS after the city sound intervention suggests that urban sounds may trigger stress

responses that decrease positive emotions. This could result in a negative effect on work ethic,

compassion, and purpose in an urban environment (Lumber et al. 2017; Mitchell & Popham,

2008).

In contrast to positive mood states, negative affect scores (NAS) were significantly

higher after the city sound intervention, but significantly lower after listening to seven minutes of

pre-recorded nature sounds (Figure 2 b). Like PAS, the NAS results were in accordance with the

study by Berman et al. (2012), where NAS scores were higher in urban environments and lower

in natural environments. Higher NAS scores suggest that humans have a more negative, stressed

mood when in an urban setting. For this study, specifically, the NAS after the seven minutes of

nature sounds scored a 10.8  0.32. This result is close to the minimum possible for NAS, as

PANAS scores range from ten to fifty. In contrast, low NAS scores after the nature sound

intervention suggests that listening to a pre-recorded set of natural sounds in any situation may

help mitigate the effects of negative emotions. Minimizing the feeling of negative emotions

likely results from the deactivation of the SNS and engagement of the PNS; thus, balancing the

autonomic nervous system and relieving stress-related symptoms.

In addition, this study evaluated innate preferences of participants for urban or nature

environments before the sound interventions. There was a statistically significant difference

between perception of the two environments (Figure 3), with a higher preference for nature

sounds (i.e., all but two participants chose a six or seven on a Likert scale of one to seven). This

is in agreement with similar studies in which natural sounds and environments were preferred to

city workspaces (van den Berg et al., 2007; Hunter & Askarinejad, 2015; Mangone et al., 2017).

The preference for nature may derive through experience as well as evolutionary history (Blades,

1989; Orri et al. 2019). Humans may have an innate connection to natural environments as our

ancestors evolved in direct contact with nature and gathered in small groups. However, the effect

of experience, whether children are raised in an urban or rural community, may influence

subsequent preferences later in life (Cohen & Horm-Wingerd, 1993). Results from this study

suggest that humans may still perceive natural environments as more relaxing and linked to less

negative emotions.

Due to the Covid-19 pandemic, this study was completed remotely. Although participants

had the benefit of completing the sound trials in the comfort of their own homes, there are a few

difficulties related to working remotely. Communication with each participant was mostly done

via email, with the only visual and voice contact being through the WebEx videoconference call

during the trial. Additionally, each participant used their own device and headphones to play

sounds. Across operating systems and brands, the free Youlean loudness meter did not always

work efficiently for each participant. Some participants experienced the 70-dB level reading on

this meter as somewhat uncomfortably loud. In these cases, the participant was asked to modify

the volume of their devices to a level they would consider to be a comfortable, normal

conversational volume. Although this volume might not have been exactly 70 dB, the goal was

that every participant would at least perceive the volume as “conversational” volume. So, we

assume that volume level was set by each participant to an average of 70 dB. The reliance on

each participant to record their own physiological vitals might have also been subject to some

random error, but with the aid of the experimenter guiding students through these tasks, and

keeping the time for the measurements, random effects should have been minimized. As a final

note, having a within-subject design led each trial to be just under an hour. A few participants

had notes that mentioned their fatigue on the second set of sounds (determined by a random

number generator). This case was rare as most participants commented on how quick the trial

seemed to last. Generally, it is also important to note a potential bias in terms of sound

perception that humans may experience. Associations with sounds may be linked to different

cultural perceptions across the world, with over 6,000 languages spoken and the difference in

cross-modal mappings as a result of nonarbitrary associations (Blasi et al. 2016).

Despite the problems that come with virtual research, there is the potential of finding

accessible tools that could improve general feelings of well-being during a global pandemic.

Amongst the challenges that COVID-19 has brought, individuals have been forced to isolate

themselves and many may have limited access to natural space. Finding accessible ways to

nature may help to cope with potential negative psychological effects related to a global

pandemic (Xiao et al. 2020). Those who are experiencing elevations in anxiety and don’t have

access to natural spaces could use these findings to explore whether recordings of sounds from

natural environments may bring some relief by engaging parasympathetic nervous system

activity and deactivating the sympathetic nervous system, which is associated to stress responses

(Hoffman et al. 2017). However, humans may have different preferences for a single, dominant

sense, and nature sounds may not be relaxing for everyone (Zurek 1993; Lakie & Loram, 2006).

In any case, a full immersion in nature, as happens during a walk in the woods, may override a

single dominant sense and help to reconnect with our roots in nature.

LITERATURE CITED

Alvarsson, J. J., Wiens, S., & Nilsson, M. E. (2010). Stress recovery during exposure to nature

sound and environmental noise. International journal of environmental research and

public health, 7(3), 1036-1046.

Amiri, M. J., Sadeghi, T., & Bonabi, T. N. (2017). The effect of natural sounds on the anxiety of

patients undergoing coronary artery bypass graft surgery. Perioperative Medicine, 6(1),

17.

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APPENDIX A. PARTICIPANT INFORMED CONSENT

INFORMED CONSENT FOR THE EFFECTS OF NATURAL AND MANMADE SOUNDS ON

THE PHYSIOLOGICAL AND PSYCHOLOGICAL WELLNESS IN FEMALE COLLEGE

STUDENTS

Key Information

This study will focus on evaluating the impacts of nature and manmade sounds on physiological

and psychological measures in females. Each individual participant will listen to 2 sets of sounds

(nature and city-related sounds) for a total of 14 minutes. Sounds will be played to the participant

at a conversational volume through their own personal headphones. This research will be done

remotely using WebEx software. Each individual online trial will last approximately one hour,

which will include both collection time and instruction. All information collected by the researcher

will be confidential. Since the study may cause changes in heart rate, we kindly ask that any

individuals with current or past heart disease to not participate in this study.

Introduction of the Researcher

The principal researcher is Domenic DiPietro. Domenic is a Master of Science student in

Biological Sciences working under the supervision of Dr. Maria G. Bidart. The researcher’s

topics revolve around the benefits of natural environments in a world where urbanization is

becoming seemingly more needed. As the individual participant, you were contacted based upon

your participation in previous studies with our lab or by connection to other graduate students in

the Biological Sciences department. To fit criteria of the research, each individual participant

must be female and between the age of 18 and 28 years.

Purpose

This study aims to boost the wellness of individuals that might live in big cities, or other areas

that have little access to natural space. If results are positive, anybody with internet access can

easily find natural sound mixes and help boost productivity while reducing the effects of stress

and work-related anxiety. There will be no direct benefits to each individual participant.

Procedure

Each participant will be asked to use their own headphones to listen to a set of nature and

manmade city sounds throughout experimentation. The researcher and participant will meet

remotely using a WebEx chatroom upon a previously agreed time. Each participant will fill out

a survey regarding how they feel before the trial , and will be asked to manually record their own

heart rate and respiration rate. Seven minutes of sound will be played for the participant before

the survey and vitals are taken again. There will be a ten-minute break before the second set of

sounds is played for another seven minutes. Final vitals and survey response will follow the

second set of sounds. Each participant is only required for one remote visit. After all

measurements are taken, and if the participant has no questions, the study is finished for the

individual participant.

Voluntary Nature

Please understand that your participation is voluntary. At any point throughout the study, you

can withdraw if you feel uncomfortable. If any questions, measurements, or situations are

uncomfortable, we can discontinue the study if the concerns cannot be properly accommodated.

If the study is not completed, your relationship with Bowling Green State University, any

teachers, students, or employment positions will not be affected. All interactions with the

researcher are confidential and will not be disclosed in the event of discontinued study.

Confidentiality:

This study is confidential, meaning the researcher is the only person who will know the identities

of the subjects. Identities or personal experiences will not be disclosed. All data will be stored

on an external drive possessed by the researcher. Each individual participant will receive a

number as an encryption for the researcher to distinguish individuals through data analysis. The

only risk to the subject would include an accidental breach of confidentiality, in which

information about the identities of participants is disclosed to individuals other than the

researcher. To avoid this, the encryption key of participants will be kept on a file kept separately

from the data in the experimenter’s research notebook.

Contact Information

If you’d like to contact the researchers for the study, you can directly email Domenic or Dr.

Bidart (Advisor)

Domenic DiPietro: ddipiet@bgsu.edu

Dr. Bidart: gbidart@bgsu.edu

You may also contact the Chair of our Bowling Green State University Review Board via

telephone or email if you have any questions regarding your rights as a participant in this study.

419-372-7716

orc@bgsu.edu

“I have been informed of the study’s purposes, methods, and the risks I’m taking by

participating. I have asked any questions I may have, and I know that my participation is

continually voluntary. I agree to participate in this study.”

____________________________________

Participant Signature and Date

APPENDIX B. BASELINE QUESTIONNAIRE

Subject No. _____________

Yes_______

No_______

Today, have you had any abnormal amounts of coffee, soda, or other energy drink

that would have excessive caffeine or sugar? If so, please write which drink and how

much you have had in the space below.

Yes_______

No_______

Have you done any strenuous activity in the past few hours, so that there is a

possibility you could be physically or mentally fatigued in any way? If so, please list

the circumstance(s) below.

Yes_______

No_______

Do you take any medications for stress, anxiety, or the alleviation or aid of

attention?

Approximately how many hours of sleep have you had in the past 24 hours?

Yes_______

No _______

Do you understand that if you feel too uncomfortable in any way the sound trials

can be interrupted and you do not need to continue?

Perception of nature and urban sounds prior to trials

1) How do you perceive Urban sounds (traffic, sirens, etc.)? (1 = Very Stressful, 7 = Very

Relaxing)

1234567

2) How do you perceive Nature Sounds (bird songs, water sounds)? (1 = Very Stressful, 7 =

Very Relaxing)

1234567

Signature _____________________________________________________

APPENDIX C. POSITIVE AND NEGATIVE AFFECT SCHEDULE (PANAS)

QUESTIONNAIRE

With the below list of words, please write the number that best describes how you feel right

at this moment.

Very slightly or

not at all

A little

Moderately

Quite a bit Extremely

Score

Feelings/emotions

Interested

Distressed

Excited

Upset

Strong

Guilty

Scared

Hostile

Enthusiastic

Proud

Score

Feelings/emotions

Irritable

Alert

Ashamed

Inspired

Nervous

Determined

Attentive

Jittery

Active

Afraid

APPENDIX D. PARTICIPANT INSTRUCTIONS FOR ONLINE LOUDNESS METER

The following URLs from “Freesound.org” are where the experimenter acquired the sounds for

this study under the “Creative Commons 0” copyright license:

Nature Sounds:

https://freesound.org/people/Vonora/sounds/269570/

https://freesound.org/people/jmiddlesworth/sounds/364663/

https://freesound.org/people/jackmurrayofficial/sounds/433589/

City Sounds:

https://freesound.org/people/MultiMax2121/sounds/156869/

https://freesound.org/people/sortan/sounds/220931/

https://freesound.org/people/2hear/sounds/317533/

This final URL from “Freesound.org” was acquired for use in city sounds under the “Creative

Commons Use” copyright license, in which credit is given to the sound creator, Klankbeeld

(https://freesound.org/people/klankbeeld/).

https://freesound.org/people/klankbeeld/sounds/506019/

Below is a link containing the “Creative Commons Use” copyright license:

https://creativecommons.org/licenses/by/3.0/

APPENDIX E. FIGURES

Baseline

After City Sounds After Nature Sounds

Baseline

After City Sounds After Nature Sounds

Figure 1. Effects of separate, 7-minute city and nature sound interventions on means and

standard errors of the following vital signs: (a) manually recorded heart rate and (b) respiration

rate. Different letters denote statistically significant differences between the means of the

variables (P < 0.05) in a population of 20 individuals.

3535

3030

2525

2020

1515

1010

BaBsaesleilninee

Baseline

AftAefrteCriCtyit ySSoouunnddss AfteArftNeraNtautruereSSoouunnddss

After City Sounds After Nature Sounds

Figure 2. Effects of separate, 7-minute city and nature sound interventions on the Positive and

Negative Affect Schedule (PANAS) questionnaire scores. Means and standard errors are

separated into (a) Positive Affect Scores (PAS), and (b) Negative Affect Scores (NAS).

Different letters denote a statistically significant difference between the means of the scores

(P < 0.05).

City

Nature

Figure 3. Means of perceived comfort with city (man-made) sounds and nature sounds using a

Likert scale of 1-7 (1 = very stressful and 7 = very relaxing). Different letters denote a

statistically significant difference between the means of the scores (P < 0.05).

APPENDIX F. TABLES

Table 1

Mean score and standard deviation (SD) for each individual emotion or feeling from the positive

and negative affect schedule (PANAS) on a Likert scale of 1 – 5, with a score of 1 signifying

“very slightly or not at all” and a score of 5 signifying “extremely”.

PANAS Emotion/Feeling

Positive Affect Emotions

Interested

Excited

Strong

Enthusiastic

Proud

Alert

Inspired

Determined

Attentive

Active

Negative Affect Emotions

Baseline

Mean

3.80

0.22

2.95

0.13

2.55

0.22

3.15

0.00

2.55

0.21

3.30

0.07

2.40

0.10

2.55

0.00

3.40

0.26

2.35

0.29

After City Sounds

Mean

2.80

0.24

2.20

0.24

1.85

0.22

2.10

0.18

1.90

0.21

3.05

0.07

1.55

0.15

1.90

0.15

2.95

0.25

1.90

0.22

After Nature Sounds

Mean

3.15

0.27

2.40

0.05

2.40

0.23

2.70

0.00

2.30

0.29

2.60

0.00

2.75

0.00

2.20

0.00

3.00

0.26

1.75

0.23

Distressed

Upset

Guilty

Scared

Hostile

Irritable

Ashamed

Nervous

Jittery

Afraid

1.35

0.05

2.30

0.19

1.05

0.10

1.00

0.23

1.50

0.23

1.00

0.27

1.10

0.07

1.10

0.07

1.00

0.00

1.25

0.22

1.40

0.20

1.00

0.30

1.00

0.26

1.60

0.32

1.00

0.16

1.05

0.30

2.00

0.14

1.10

0.28

1.10

0.18

1.10

0.23

1.00

0.16

1.95

0.24

2.00

0.23

1.25

0.13

1.80

0.24

2.40

0.18

1.35

0.16

1.10

0.07

1.25

0.12

1.05

0.05

Table 2

Analyses of variance evaluating the effects of sound treatments (city and nature sounds) and

subjects (in a within-subject design) on vital signs and positive and negative affect scores (PAS

and NAS, respectively). Asterisks denote a statistically significant value (P < 0.0001).

Source

Heart Rate

Respiration Rate

Positive Affect Score

Negative Affect Score

Treatments

F-value

2, 38

2.99

2, 38

12.87*

2, 38

15.72*

2, 38

24.84*

Subjects

F-value

19, 38

25.59*

19, 38

6.06*

19, 38

9.12*

19, 38

1.73

Table 3

Mean and standard error values of heart rate (number of beats per minute), respiration rate

(number of breaths per minute), positive affect score (PAS), and negative affect score (NAS).

Measurements were recorded at baseline, then after listening to separate, 7-minute interventions

of natural and urban sounds.

Heart Rate

Respiration Rate

PAS

NAS

Baseline

Mean

70.5

5.50

15.4

0.85

29.0

1.52

12.7

0.55

After City Sounds

Mean

73.6

5.53

17.15

0.90

22.2

1.46

16.7

1.32

After Nature Sounds

Mean

67.6

4.73

13.2

0.96

25.3

1.78

10.8

0.33