PROCEEDINGS of the
23rd International Congress on Acoustics
9 to 13 September 2019 in Aachen, Germany

Exploring associations between soundscape assessment, perceived
safety and well-being: a pilot field study in Granary Square, London
Francesco ALETTA1; Luca MOLINERO2; Arianna ASTOLFI2; Sonja DI BLASIO2; Louena
SHTREPI2; Tin OBERMAN1; Jian KANG1
1

Institute for Environmental Design and Engineering, University College London, United Kingdom
2

Department of Energy, Polytechnic Institute of Turin, Italy

ABSTRACTThe number of soundscape studies is growing steadily over time and the discipline as a whole is going
through a process of methodological standardization. Yet, more empirical evidence is needed about thebenefits of experiencing positive soundscapes for health, well-being and quality of life. In this study, a pilot
questionnaire was distributed to 50 users of a public open space in London (Granary Square), which
consisted of a standardized protocol for collecting soundscape data (ISO 12913-2:2018, Method A), theWorld Health Organisation-Five Well-Being questionnaire (WHO-5) and a short protocol to assess perceived
safety. Results show that associations between negative soundscape dimensions and lower well-being scores
exist at a statistically significant level (p < .05) and other further insights into the relationships between soundperception and perceived safety. By making a stronger case for policy makers and planners, these findings
contribute to the discourse of approaching the management of the urban acoustic environments in a proactive
rather than reactive way, to promote healthy and supportive urban spaces.
Keywords: Soundscape, Well-being, Perceived safety; Quality of Life, Public space

1. INTRODUCTION
Soundscape studies are gaining momentum in the broader field of environmental acoustics andtheir impact is starting to be reflected in practice and policy documents and initiatives (1, 2). Theinternational research community is thus putting a lot of effort into standardizing frameworks,
definitions and methodologies, to foster best practices in soundscape characterization, managementand design (3–6). Nonetheless, in order to increase its impact and outreach, soundscape research is stillrequired to provide empirical evidence of the additional benefits given by this approach (7),particularly in the context of urban design, public health and quality of life, which are dominating the
public discourse and the socio-political agenda (8–10).
In a recent literature review on associations between soundscape dimension and health effects,
Aletta et al. (11) pointed out that in future soundscape studies where individual responses on the
acoustic environments are gathered, additional items should be included in the data collection
protocols, referring to health, quality of life and other factors affecting the holistic experience of aplace,so that associations can be established between these domains. Exploring such relationships
would ultimately allow supporting a public health argument at policy-making level, and boost thedevelopment of operational tools, such as soundscape indicators and prediction models (12, 13).
For this purpose, a pilot study was performed within the broader “Soundscape Indices – SSID”
project (14) and a questionnaire was submitted to users of an open public space, which included items
related to the perception of the acoustic environment (i.e., the soundscape), self -reported well-being
and perceived safety. The aim of this pilot was evaluating whether associations between the three
aforementioned components could be identified. In parallel, binaural recordings were performed, andthe main corresponding sound levels and psychoacoustic parameters were computed, so that
objectively measured values could potentially inform the interpretation of the percep tual data.

1

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f.aletta@ucl.ac.uk

2. METHODS
Data collection was performed in accordance with the recently released Part 2 of the ISO
soundscape standard (15). The following subsections report on the general procedure implemented forthe survey, the protocol used to gather individual responses about the perception of the environment
and the acoustic measurements performed via binaural recordings. This study received ethicalapproval in accordance with UCL Research Ethics policy through the procedure implemented at theInstitute for Environmental Design and Engineering (Departmental approver’s letter on 17 th July2018).
The case study is Granary Square (Figure 1), located in central London (UK). The rationale forselecting this site is that it offers a reasonably broad range of possible acoustic environments (variety
of sound sources) and is used by different types of people (e.g., workers vs. tourist, different age
groups, etc.) for several activities (e.g., leisure, work, commuting, etc.).

Figure 1 – 360-degree views from different spots in Granary Square, the case study in central London.
2.1 Survey procedure
The survey took place between the 18 th and the 25 th of July, 2018. Acoustic measurements were
performed and questionnaires submitted to members of the public during week days, between 10:00 am
and 05:00pm, for a total of five data collection sessions. A researcher would approach potential
volunteers individually to fill in the questionnaire (described in Section 2.2) and perform a one -minutebinaural recording (described in Section 2.3) while they were completing the form. The questionnaire
was presented using a Google form document showed to participants via a tablet, or using printed
forms. Informed consent to take part in the study was sought from participants in advance. Completingthe questionnaire usually took 10 minutes for each participant.
2.2 Questionnaire
The questionnaire used in this pilot study consisted of three main themes, each one being divided inquestion categories (not available to participants) that were made in turn of several items: (a)soundscape; (b) well-being; and (c) perceived safety. The questionnaire used on site is reported inTable 1.
The soundscape theme consisted of three question categories, namely: sound sources, perceived
affective quality and overall quality. This part of the questionnaire was derived from the standardiz ed
protocol proposed in Method A of the soundscape ISO technical specifications (15). The well-being
theme referred to the Five Well-Being Index (WHO-5), which is a short self-reported measure ofmental well-being (16).

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Table 1 – Questionnaire used on site; the first three categories refer to the soundscape theme, whilst theremaining categories refer to the well-being and perceived safety themes.
Category

Question

Item(s)Scale/Response TypeSound

To what extent do you

Environmental noise (e.g., traffic,

Not at all (1); A little (2); Moderately

sourcespresently hear the fourconstruction, industry); Sounds from(3); A lot (4); Dominates completely

following types of sounds?

human beings (e.g., conversation,(5)

laughter, children at play, footsteps);
Natural sounds (e.g., singing birds,
flowing water, wind in vegetation)
Perceived

For each of the 8 scales

Pleasant; Chaotic; Vibrant; Uneventful;Strongly agree (1); Agree (2); Neither

affective

below, to what extent do you

Calm; Annoying; Eventful; Monotonous

agree, nor disagree (3); Disagree (4);qualityagree or disagree that theStrongly disagree (5)present surrounding soundenvironment is…
Overall

Overall, how would you–

Very good (1); Good (2); Neither

qualitydescribe the present

good, nor bad (3); Bad (4); Very bad

surrounding sound(5)

environment?
Overall, to what extent is the–present surrounding soundNot at all (1); Slightly (2); Moderately(3); Very (4); Perfectly (5)environment appropriate to
the present place?
WHO-5

Perceived
safetyPlease indicate for each of

I have felt cheerful and in good spirits; I

All of the time (5); Most of the time

the five statements which ishave felt calm and relaxed; I have felt(4); More than half of the time (3);closest to how you have been

active and vigorous; I woke up feelingLess than half of the time (2); Some offeeling over the last two

fresh and rested; My daily life has been

the time (1); At no time (0)weeks

filled with things that interest me

To what extent do you agree

I feel worried; I feel safe

Strongly agree (1); Agree (2); Neither

or disagree with theagree, nor disagree (3); Disagree (4);following statements about

Strongly disagree (5)the surrounding
environment?

The protocol has been found to have adequate clinical validity in screening for depression andgeneral well-being (17). The perceived safety theme referred to assessing safety (or lack thereof),
perceived by users of a public space (e.g., fear of aggression vs. relaxation etc.). There are no clearly
established or standardized protocols to assess such dimension, but a few tools have been proposedover the years, so the items proposed in this study refer to other studies retrieved in the literature (18,
19).

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2.3 Binaural recordings
The ISO/TS 12913-2:2018 document requires the acoustic environment of the investigated site to
be characterised through binaural (or other spatial audio) recordings. The rationale is also being able tosupport the analysis of the subjective data with measured physical parameters. Measurements were
performed using a binaural recording system, composed of portable audio recorder EDIROL(ROLAND, R-44, 24 bit 192 Hz DIGITAL), connected to an head-mounted pair of 1/8”
omnidirectional microphones DPA MICROPHONE (NEUTRIK, mc-mmx, DAD6001 P48 - 12V-48V)
equipped with small windshields. The recording time was a one-minute interval, which was recorded
simultaneously while the participants were filling the questionnaire. During the measurement, theoperator (height: 1.70 m) was staying as close as possible to the participants/listeners’ position,
keeping the head steady to conduct the binaural recordings in a stationary condition. In order tominimize the influence of unwanted reflections, a minimum distance of one meter from reflecting
surfaces was kept.

3. RESULTS
3.1 Definition and analysis of the variables involved
For the soundscape-related questions (i.e., the Sound sources, Perceived affective quality, andOverall quality categories in Table 1) each item was considered individually as an ordinal variable(ranging from 1 to 5). The scales for some items of these categories were “flipped” (regardless of how
the questions were originally presented to participants) so that a higher score would always reflect ahigher level of “agreement” with the attribute/statement considered.
Regarding the items of the WHO-5 category, the WHO guidelines recommend a formula tocombine the five items into a single normalized well-being score ranging from 0 (worst outcome) to100 (best outcome) (16). However, considering the small sample size of this pilot study and the limited
statistical power that this would have implied using the score in association with other variables, inthis context a different clustering approach was used to define a new well-being variable (20). In orderto define a “Self-reported Well-being” variable, a k-means cluster analysis was performed on thescores of the WHO-5 items; the algorithm was forced into a two-cluster solution, since a convergence
was achieved due to no or small change in cluster centres after only two iterations of the clustering
algorithm (SPSS IBM v.22). The mean scores of five items were then analysed as a function of cluster
membership. Considering the positive direction of the WHO-5 items, a high level of agreement
reflects a better well-being condition. The five items were always higher for cluster 2 than for cluster
1, therefore the two clusters were interpreted as follows: “Low” (cluster 1) and “High” (cluster 2)
well-being. These were then considered as categorical levels of the “Self-reported Well-being”
variable.
A similar approach was used for the Perceived Safety category of the questionnaire based on two
items. In order to define a new “Perceived safety” variable, a k-means cluster analysis was similarly
performed on the scores of the “I feel worried” and “I feel safe” items, forcing the algorithm into a
two-cluster solution, since a convergence was achieved due to no or small change in cluster centres
again after only two iterations of the clustering algorithm. The mean scores of two items were thenanalysed as a function of cluster membership. Considering the direction of the two scales, cluster 1
would represent “Low” perceived safety, whilst cluster 2 would represent “High” perceived safety.
These were then considered as categorical levels of the “Perceived safety” variable.
3.2 Association between soundscape, well-being and safety data
In order to explore possible associations between the items of the t hree main themes of thequestionnaire, a set of independent-samples t-tests was then run to determine if the scores of thesoundscape-related items were different between the Low (n = 24) and High (n = 26) Self-reported
Well-being groups, and between the Low (n = 21) and High (n = 29) Perceived Safety groups . This
included all the 13 variables (questions/items), corresponding to the soundscape-related items, asreported in Table 1 (i.e., Sound sources, Perceived affective quality, Overall quality).
Looking at the Self-reported Well-being analysis, for the Chaotic soundscape item, the High
well-being group (M = 2.96, SD = 0.96) had statistically significantly lower scores than the Low
well-being group (M = 3.54, SD = 0.98), t(48) = 2.119, p = .039 (Figure 3, on the left). A similar trend
emerged for the Monotonous soundscape item, where the High well-being group (M = 2.27, SD = 0.78)
had statistically significantly lower scores than the Low well-being group (M = 2.71, SD = 0.75), t(48)7949

= 2.028, p = .048 (Figure 3, on the left).
When considering the Perceived safety analysis (Figure 3, on the right), the situation is similar, buta slightly different set of variables is affected. For the Chaotic item, the High perceived safety group(M = 2.97, SD = 1.05) had statistically significantly lower scores than the Low perceived safety (M =3.62, SD = 0.81), t(48) = 2.384, p = .021. A similar trend can be observed for the Uneventful
soundscape item, where the High perceived safety group (M = 2.10, SD = 0.77) had statisticallysignificantly lower scores than the Low perceived safety group (M = 2.86, SD = 0.85), t(48) = 3.259, p= .002. The same applies to the Annoying soundscape item: the High perceived safety group ( M = 2.14,
SD = 0.79) had statistically significantly lower scores than the Low perceived safety group (M = 2.67,
SD = 0.80), t(48) = 2.330, p = .024. Finally, a difference for the Perceived safety variable also emerged
for one of the items of the sound sources dominance. Indeed, for the Human sounds it ems, the High
perceived safety group (M = 3.55, SD = 0.57) had statistically significantly lower scores than the Low
perceived safety group (M = 4.00, SD = 0.84), t(48) = 2.252, p = .029.

Figure 3 – Left: mean scores and 95% Confidence Interval of the Chaotic and Monotonous attributes, as afunction of the Self-reported Well-Being variable; Right: mean scores and 95% Confidence Intervl of the
Human sounds variable and the Chaotic, Uneventful and Annoying attributes, as a function of the Perceived
Safety variable.
3.3 Psychoacoustic data
Psychoacoustic parameters (Loudness and Sharpness) and the A-weighted equivalent sound level(SPL) were computed from the binaural recordings, using the Simcenter LMS Testlab (Siemens PLM
Software, v.17). Figure 4 shows the distributions of the average values (arithmetic mean of the left andright channel) for the sample of 50 participants related to the three parameters. It can be observed thatsound levels were moderately high, with most of the sample between 65 and 75 dBA. Likewise,
Loudness levels for most of the sample ranged between 20 and 30 sone. The sample was also exposed
to moderately sharp acoustic environments with most of the values ranging between 1.3 and 1.6 acum.
Overall, this set of objective measures is compatible with the sound sources noted on site by the
researchers, typically consisting of human sounds, water sounds (fountains), and some traffic noiseand construction noise. In order to get further insights into possible associations between objectively
measured parameters and subjectively gathered data, a set of Spearman's rank-order correlation test
was run to assess the relationships between the physical parameters (SPL, Loudness and Sharpness)
and all the items of the soundscape and perceived safety the mes of the questionnaire. The WHO-5
items were excluded from this analysis: they refer to the previous two -week period for theinterviewees, thus associations with the levels measured on the spot would be meaningless. If
discarding internal correlations between the acoustic parameters (which are expected), only two
statistically significant associations were identified between objective and subjective measures. There
was a small positive correlation between SPL and Human sounds, rs (48) = .296, p = .037, and a small
negative correlation between Sharpness and Calm, rs (48) = -.316, p = .025.

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Figure 4 – Distributions of the mean values of the objective parameters calculated from the binaural
recordings for the 50 participants.

4. Discussion
The studies investigating directly the associations between the perception of the acoustic
environments (i.e., the soundscape) and well-being and safety-related dimensions are scarce in thecurrent body of literature. For this reason, in the context of this preliminary work, such relationships
were explored by stratifying the available sample and checking for differences in soundscapeassessments between well-being and perceived safety populations.
In this case study, statistically significant associations emerged for the well-being and perceived
safety categories with attributes in the “negative” region of the soundscape circumplex model
proposed by Axelsson et al. (21). This seems to suggest that for potentially vulnerable groups (e.g.,
those who report lower levels of well-being and perceived safety), the acoustic environment isparticularly important, since its experience might likely result in more negative soundscapes.
The finding that the Low perceived safety group reports higher perceived dominance of sounds ofhumans seems to be in contrast with previous studies, where it was suggested that human sounds(either verbal or non-verbal) might help to convey a feeling of social presence and increased safety,
regardless of the actual physical presence of people on site (18, 19). A possible explanation for this isthat this kind of studies is typically conducted in night-time situations, with no people in sight (empty
spaces): in this context, auditory information related to human presence might be beneficial. However,the present survey was conducted in a busy open public space during day-time. Thus, the Low
perceived safety group might have overestimated the human sounds as it considers them as anindicator of danger (e.g., pickpockets, anti-social behaviours, etc.). From the soundscape design
perspective, this could have some implications as one might want to let sounds other thanhuman-related ones to dominate, in order to enhance perceived safety in these urban contexts.
The positive correlation between SPLs and the perceived dominance of human sounds confirmsthat this kind of sound sources is the one contributing most to the acoustic environment of the place,which seems to support the interpretation of the implications for perceived safety mentioned above.
The negative correlation between Sharpness and the Calm soundscape attribute looks also consistent
with the previous finding, as one would expect human sounds to mainly affect the high -frequency
region of the spectrum, so when human sounds are decreasing, the sound scape is possibly assessed as
being calmer/quieter. Overall, the lack of any other correlations between perceptual dimensions andacoustic metrics highlights once again that soundscape needs to refer to a holistic assessment of a placeand other non-acoustic factors and activity-related factors need to be taken into account (22–24). Apartfrom this, some issues might also be related to the scales of the questionnaire itself , as it is difficult to
exclude at this stage that the scaling of the perceptual attributes is free from bias (25).

5. CONCLUSIONSIn this study, a pilot soundscape survey within the Soundscape Indices project was carried out in a
public square in central London. The analysis of the preliminary results highlights that for this specificcase study: The sub-set of participants associated with lower well-being scores assessed soundscapes7951

more negatively (Chaotic, Monotonous; p < .05), compared with the group with higher
well-being scores.
 The sub-set of participants associated with lower perceived safety scores assessedsoundscapes more negatively (Chaotic, Uneventful, Annoying; p < .05) and more
dominated by human sounds (p < .05), compared with the group with higher perceived
safety scores.
 A limited set of statistically significant correlations was found between the perceptual
dimensions and the psychoacoustic parameters measured during the questionnaires(SPL/Human sounds, Sharpness/Calm; p < .05).
The protocol tested for this study is currently being deployed in several partner sites around t heworld (14). The results of this pilot study suggest that relationships between soundscape, well -being
and perceived safety dimensions should be explored further with larger samples to achieve greater
statistical power and unveil other possible relationships that might not have emerged in this specificcontext. The knowledge coming from such studies should hopefully inform policy -making, planningand urban design, and contribute to the debate about the management of the urban acoustic
environments in a proactive rather than reactive way, to promote healthy and supportive urban spaces.

ACKNOWLEDGEMENTS
This research was funded through the European Research Council (ERC) Advanced Grant (no.
740696) on “Soundscape Indices” (SSID).

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