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Soundscapes: A perceptual design tool on the rise

How we perceive the sounds around us is dependent upon their inherent acoustic characteristics but also their associated meanings, context and our experience. We individuals shape the frame of reference. Exposure to unwanted, negative sounds (noise!) impacts our quality of life. Until now, our primary goal in acoustics has been to solely reduce the negative impacts of noise.

We basically live in what is left.

The soundscape approach has gained recognition in various disciplines and especially in the realm of acoustics, it has been explored as a potential design resource. It is relevant as it includes both the study of the acoustic environment on the one hand but also the human response on the other. The way we perceive the sounds around us is what matters and not only their acoustical characteristics.

Research into the perception of soundscapes has gained momentum over the past decade focusing mostly on outdoor environments but also, more recently, on indoor spaces.

This article provides an overview on the origins of soundscape research, the study of emotion and aims to answer the following questions:

How can the study of soundscapes aid at providing positive sound environments that make us thrive?

Can it be exploited as a design tool to shape the outdoor environment or more importantly indoor spaces?

What is a soundscape?

The soundscape denotes the aural equivalent of the visual landscape. It is the sum of all sounds encompassing us. In the external “urban” environment, usually the only control exercised is in respect of the worst aspects of negative elements of sound with the aim of reducing impact on our health and wellbeing. This is what we call “noise control.”

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Figure 1: Soundscape and noise control (Source: Presentation of Torresin et al. 2020 [1])

The soundscape approach in contrast focuses on preserving and protecting positive soundscape characteristics and on introducing new (wanted and positive) sounds where necessary. It explicitly includes a holistic aspect, namely in which the environment is perceived and understood by individuals or a community [2]. The soundscape concept spans trough a multitude of disciplines and includes, among others, psychological, (psycho)acoustical, physiological, and social factors (Figure 1) [1].

This has led to the publication of ISO standards [3, 4, 5] with the intention of finding consensus on the definition of the rather broad term “soundscape” but also regarding data collection, methodologies and reporting among all disciplines.

A considerable amount of effort has been spent studying and improving external, “outdoor” urban soundscapes [6]. Only recently, the soundscape approach has been applied indoors.

As we are spending 90% of our time indoors, we are familiar with evaluating the quality of the sound environment in the built environment – consciously or not. This has influenced standards and the design of such spaces beyond noise levels and the consideration of room acoustic indices such as reverberation time.

Before diving too deep into applied soundscape studies, let’s take a few steps back and look into the definition of soundscape, its origins and its relationship between the study of emotions.

The soundscape concept and its origins

The soundscape concept is deeply rooted in the pioneering work lead by R. Murray Schafer and B. Truax during the 1970s.

Schafer’s early work defined Soundscape as: “Soundscape: An environment of sound (or sonic environment) with emphasis on the way it is perceived and understood by the individual, or by a society. It thus depends on the relationship between the individual and any such environment. The term may refer to actual environments, or to abstract constructions such as musical compositions and tape montages, particularly when considered as an artificial environment. The study of the systematic relationships between humans and sonic environments is called “soundscape ecology”, whereas the creation, improvement or modelling of any such environment is a matter of “soundscape design”. “Since a soundscape is shaped by both the conscious and subliminal perceptions of the listener, soundscape analysis is based on perceptual and cognitive attributes such as foreground, background, contour, rhythm, silence, density, space and volume, from which are derived such analytical concepts as Sound Event, Keynote, Sound Signal, Sound Object and Soundmark“. [7]

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Multidisciplinarity is at the core of soundscape design.

Truax, who coined the term “soundscape design”, described it as: “Soundscape Design: A new interdiscipline combining the talents of scientists, social scientists and artists (particularly musicians). Soundscape design attempts to discover principles and to develop techniques by which the social, psychological and aesthetic quality of the acoustic environment or soundscape may be improved. The techniques of soundscape design are both educational and technical. The latter include the elimination or restriction of certain sounds (noise abatement), the evaluation of new sounds before they are introduced indiscriminately into the environment, as well as the preservation of certain sounds (sound signals including soundmarks, keynotes and sound events), and above all the imaginative combination and balancing of sounds to create attractive and stimulating acoustic environments. Soundscape design may also include the composition of actual environments, and in this respect it is contiguous with contemporary musical composition”. [8]

How can we measure emotions?

Now that we know what a soundscape is and where the term stems from, let’s look into the perception. In order to improve existing soundscapes, we must gain insights into how soundscapes are being perceived by us, humans. We therefore need to dive a little deeper into the study of the structure of affect.

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Emotional judgments and affective self-ratings are often found arrayed in a circular arrangement, referred to as a circumplex structure [9]. A circumplex is a two-dimensional, circular structure in which single attributes correlate highly with those attributes nearby on the circumference of the circle, correlate near zero with those attributes one-quarter way (90°) around the circle, and correlate inversely with those attributes directly opposite on the circle [9].

Larsen and Diener [9] presented a model in which the horizontal axis represents unpleasant-pleasant affective quality and the vertical axis high/low activations. The affective states are organised according to these axes. Affective states vary on hedonic valence, so any state falling in the left half of this model is referenced with the label “Unpleasant” and any state falling in the right half of Figure 2 is referenced with the label “Pleasant” [9]. Similarly, affective states vary on activation, so any state falling in the upper half of Figure 2 is referenced with the label “High Activation” and any state falling in the bottom half of Figure 2 is referenced with the label “Low Activation” [9].

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Figure 2: The Self-Report Affect Circumplex (adapted) (Source: Larsen and Diener [1992] [9])

More recent studies [6, 10, 11] demonstrated that the circumplex model can be applied in outdoor soundscape research. They adapted the model (from Figure 2) and proposed a measurement system for soundscape quality, which consisted of a two-dimensional space denoted by the attributes:  Pleasant, Exciting, Eventful, Chaotic, Unpleasant, Monotonous, Uneventful, and Quiet, as eight vectors separated by 45° in a circumplex model of soundscape perception (see Figure 3). This model has also been adopted in the ISO standard ISO/TS 12913-3:2019.

Consequently, a pleasant and uneventful soundscape could be perceived as calm whereas an unpleasant and eventful soundscape could be perceived as chaotic. In addition, the meaning of sounds (denoted as “sound categories” in [6]) can be related to those attributes.

They found that soundscapes dominated by technological sounds were perceived to be unpleasant, soundscape excerpts dominated by natural sounds to be mostly pleasant, and soundscape excerpts dominated by human sounds to be eventful [6].

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Figure 3: Circumplex model of affect relating to soundscape perception proposed by Axelsson et al. [6]

Let’s move inside

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Well, only few studies looked into indoor soundscapes. Torresin et al. [12] asked a panel of experts on the similarities between outdoor and indoor soundscape approaches. In short: they are fairly similar!

When comparing both approaches, responses from the panel of experts were categorized into three main points [12]:

  1. Differences in context: While people spend only periods of time outdoors, either for commuting from point A to point B or relaxing, they can choose their most preferred path or space through the city or nature. People spend most of their time indoors where they usually do not have a choice for a favorable, more positively sounding workplace and are thus “forced” into a specific sound environment.
  2. Differences in the acoustic environment: Enclosed spaces can be affected by a combination of noise intrusion (from outdoors) and indoor generated sounds. They are characterised by a reverberant sound field that can amplify both sounds and noises.
  3. Differences in soundscape strategies: With regard to the difference in soundscape strategies, Torresin et al. highlight that if “positive” sounds are added to the indoor soundscape, those must be adapted for the usage of the space, creating supportive environments depending on the tasks to be performed and meeting the personal preference, ideally after being negotiated with final users. “Natural features and active systems playing back sounds do not replace a proper acoustic design.” [12]

Approaching indoor spaces from an acoustic design perspective, the priorities should always be:

First acoustic design (activity based), then soundscape design. Thus, prior to removing or adding sounds to an existing indoor environment, the space must be designed acoustically including appropriate sound insulation and room acoustics. The latter through the use of absorptive elements, such as absorptive ceilings and wall absorbers.

How do we perceive multi-faceted indoor soundscapes?

In a different study Torresin et al. [13] explored the main underlying perceptual dimensions (emotions) of indoor soundscapes in indoor residential living rooms and suggest a measurement system of indoor soundscape perception.

They found that comfort, content and familiarity are most important. Their Comfort-Content plot resembles the circumplex model by Axelsson [6] with an adjustment. It is defined by two main orthogonal axes, Comfort and Content, and two additional axes, Engagement and Privacy – Control, rotated 45° on the same plane (see Figure 4).

Figure 4: Comfort – Content plot adapted and simplified from Torresin [13] (adapted from ISO/TS 12913 – 3 [5] and Axelsson et al. [6])
To improve indoor soundscape quality, this model provides an outline and guidance which constructs should be assessed through questionnaires and the actions that may be taken. In applying this approach, effects of different materials, space layout, and building technologies can be evaluated in terms of soundscape outcomes providing a perceptual perspective to building and room acoustics [13].

This model holds true for living rooms but how about the spaces that challenge us the most: workplaces?

It would be highly relevant to expand this type of research to various other indoor environments such as office, healthcare and educational spaces to understand how these multi-faceted soundscapes are being perceived. Since these types of spaces are highly complex in terms of activities, layout, sound sources and challenging in terms of performed cognitive tasks, variations may be expected. All those spaces listed above are in need for supportive soundscapes.

While we previously lacked the appropriate design tools, we now have a powerful way of bringing the perceptual “human” aspect back into the center of design. Indoor spaces should be the result of an integrated, holistic planning process and the soundscape approach fills the gap.

For acousticians, the premise should be to integrate soundscape design as an addition to their pallet of acoustic design tools to shape a built environment for the ear, the eye and the mind.

A remaining challenge in soundscape design is the identification of appropriate acoustic and/or psychoacoustic indices to facilitate this perceptual assessment. This subject will be further explored in an upcoming Acoustic Bulletin article.

 

Author: Achim Klein, Concept Developer for Office Environments at Ecophon

 

Sources

[1] Torresin S, Albatici R, Aletta F, Babich F, Bourdeau E, Harvey-Clark J, Kang J, Lavia L, “Five questions on the indoor soundscape approach for regenerative buildings” Presentation Inter-Noise 2020, Source: https://www.apexacoustics.co.uk/five-questions-on-the-indoor-soundscape-approach-for-regenerative-buildings/ (last accessed June 2021)

[2] Dubois D, Guastavino C, and Raimbault M, “A cognitive approach to urban soundscapes:

Using verbal data to access everyday life auditory categories”. Acta Acustica United with Acustica, 92:865-874, 2006.

[3] DIN ISO 12913-1:2018-02 “Acoustics – Soundscape – Part 1: Definition and conceptual framework” (ISO 12913-1:2014)

[4] DIN ISO/TS 12913-2:2020-11 “Acoustics – Soundscape – Part 2: Data collection and reporting requirements” (ISO/TS 12913-2:2018)

[5] ISO/TS 12913-3:2019 “Acoustics — Soundscape — Part 3: Data analysis”

[6] Axelsson O, Nilsson ME, and Berglund B, “A principal components model of soundscape perception”. J. Acoust. Soc. Am., 128(5):2836{2846, 2010.

[7] Schafer M, “The new soundscape”, Universal Edition, Vienna, 1969.

[8] Truax B, “Handbook of Acoustic Ecology”, 2nd Edition. (Cambridge Street,Vancouver Canada), 1999.

[9] Larsen R. J. and Diener E, “Promises and problems with the circumplex model of emotion”, Review of Personality and Social Psychology, 13:25-59, 1992.

[10] Berglund B, Nilsson M, and Axelsson O, “Soundscape psychophysics in place”. In Proceedings of Inter-Noise 2007, Istanbul, Turkey, August 2007.

[11] O. Axelsson, “May information load be the key dimension underlying soundscape perception”, In Proceedings of Inter-Noise 2009, Ottawa, Canada, August 2009.

[12] Torresin S, Albatici R, Aletta F, Babich F, Bourdeau E, Harvey-Clark J, Kang J, Lavia L, “Five questions on the indoor soundscape approach for regenerative buildings”, In Proceedings of Inter-Noise 2020.

[13] Torresin S, Albatici R, Aletta F, Babich F, Oberman T, Siboni S, Kang J, Indoor soundscape assessment: A principal components model of acoustic perception in residential buildings, Building and Environment (2020), doi: https://doi.org/10.1016/j.buildenv.2020.107152.

About Sound 196 Acoustics miscellaneous 222 Office Environments 120 Psychoacoustics 35 Research 165

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