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

Soundscape standardization dares the impossible - Case studies
valuing current soundscape standards
André FIEBIG1
1

Technische Universität Berlin, Germany

ABSTRACT
Recently, the ISO/TS 12913-2, the second part of the ISO soundscape series, was published supporting
detailed information on data collection and reporting for studies using the soundscape approach. This part
includes guidelines for soundwalks, interviews, acoustical measurements and defines minimum reporting
requirements. The conceptual framework and soundscape related definitions are provided by the ISO
12913-1. Finally, part 3 of ISO 12913 is underway addressing aspects and needs of the data analysis. This
ISO soundscape series provides a foundation for communication across disciplines and offers guidance on
how to perform soundscape investigations, but at the same time the question could be raised whether aconcept asking for a holistic, context-sensitive view can be subject to standardization at all. The ISO working
group had to address this issue in detail. The paper will reflect on the apparent contrast between identifying acommon methodological basis of soundscape studies for standardization and the general holistic requirementof the concept soundscape. Based on case studies, views on the apparent conflict are discussed and the valueof soundscape standards harmonizing the data collection process is assessed by considering the outcome ofsoundscape case studies.
Keywords: Soundscape, environmental noise assessment

1. INTRODUCTION
Investigations using the soundscape approach have a history over decades. Based on literature
reviews it is evident that soundscape investigations and research gain considerably in popularity. For
example, To et al. showed by a systematic review that soundscape studies were getting popular since2005, while soundscape studies in Asian countries have become more popular since 2011 [1].
According to To et al. the number of publications per year has increased rapidly and this trend still
continues till this day. Unfortunately, a major drawback of this development impeding a stronger
impact on community noise and environmental noise assessment applications was apparently that a
broad diversity of opinions about the definition of soundscape and the general aims of soundscapestudies existed and thus the use of the term ‘soundscape’ has become idiosyncratic and ambiguous as
it is stated in the introduction of the first international soundscape standard [2]. The definition of theterm ‘soundscape’ in an ISO document and providing a conceptual framework, which describes theprocess of perceiving our acoustic environment, might help to overcome such drawbacks. Researchers
can now rely on the provided definitions, which were based on a common agreement by the working
group members and experts. Or researchers can apply a deviating definition relating their differingsoundscape understanding to the definitions provided in ISO 12913-1 [2]. A standard can provide
orientation for followers as well as opponents.
The same applies for the data collection in soundscape investigations. It is broadly acknowledgedthat soundscape as a perceptual construct of an acoustic environment in context is a multifaceted
phenomenon and therefore cannot be measured with a single number [3]. In order to ‘measure’
perception in context a multitude of methods for data collection were applied focusing on qualitativeor quantitative methodologies at almost equal measure. According to Botteldooren et al. interviews orquestionnaires are most commonly used in soundscape investigations [3]. In most cases, these tools areapplied in a soundwalk, which describes a method that implies a walk in an area with a focus onlistening to the acoustic environment [4]. Thus, the ISO/TS 12913-2 aims for harmonizing thecollection of data by which relevant information on the key components people, acoustic environment
1

andre.fiebig@tu-berlin.de6081

and context is obtained, measured and reported and provides detailed information about the mostcommon data collection methods: How to do soundwalks, how to apply questionnaires, how to conduct
interviews, how to perform acoustic measurements [4].

2. Aspects of standardization
2.1 Acoustic measurements
Recordings of acoustic environments build the foundation in soundscape research throughanalyzing and understanding the soundscape in a real or virtual environment [5]. The ISO/TS 12913-2
defines that the acoustic environment must be binaurally recorded. It is noted that b inaural acoustic
measurements record sound as if a human listener is present in the original sound field maintaining all
spatial information. According to the ISO/TS 12913-2 binaural recordings should be the basis foraurally adequate analysis, for the reproduction of acoustic enviro nments (e.g. in laboratory-based
listening experiments) or for the purpose of preservation and archiving. Hong et al. reviewed applied
spatial audio recording techniques for soundscape design, which were commonly used and concluded
that binaural measurement systems as recording technique for soundscape studies is most commonlyused due to its simplicity providing a good spatial quality for static listening positions [5]. Forinteractive spatial audio reproduction in soundscape studies Ambisonics is currently the leading
recording technique but lacks international standards so far to rely on.
2.1.1 Experimental study to investigate the need for binaural measurements
Several studies investigating soundscapes still work with monaural recordings for acousticalanalysis and playback. According to the current technical specification ISO/TS 12913 -2 the use of
binaural measurements methods is mandatory maintaining all spatial information. In order toinvestigate the need for binaural data in soundscape studies an experiment was carried out analyzing
perceptual and judgmental differences respectively due to the used recording technique. The studied
research question was whether binaural data in comparison to monaural data of the same acoustic
environment yield different soundscape related assessments in a laboratory context?
MethodA with-subject design of experiment was carried out, where the participants received an instruction
with incomplete information about the main goal of the study.
Subjects
16 subjects (12 male, 4 female) with the average age of 25.9 (standard deviation ±2.9) took part in
the experiment. All participants reported normal hearing. In agreement with ethical procedures,
written consent was obtained from all of the participants.
Apparatus
All sounds were presented via a programmable equalizer (labP2) applying automatically thecorresponding equalization for playback of binaural signals and headphones (HD 650). The playback
system was calibrated and equalized. Instruction texts and interview questions were presented oncomputer screens. All assessments were collected via touchscreen.
Stimuli
Recordings of environmental noises recorded in different cities (Berlin, Düsseldorf, Osaka, London,
Sheffield) were presented. The sounds were simultaneously recorded with a calibrated monauralmicrophone (M 360 ICP microphone ¼“, Microtech Gefell) and a calibrated binaural headset(SQobold in combination with BHS II, HEAD acoustics) at the same location. All sound samples wereedited to duration of 30 s. Figure 1 shows the spectra of the two recordings of one location (Osaka
Kansai, Japan). Although the spectra show similarities, as expected they are far from being identical.
Due to the equalization of a binaural recording to have signals for the acoustical analysis available
which are fairly compatible to single microphone measurements, the determined sound pressure levelor loudness values are comparable (monaural recording: LAeq : 68.7 dB(A), loudness: 27 sone; binaural
recording: LAeq_left : 69.8 dB(A), LAeq_right : 69.2 dB(A), loudness left : 26.9 sone, loudness right : 26.0 soneaccording to ISO 532-1 [6]).

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Figure 1 – Environmental noise recordings of Osaka Kansai (left: monaural recording; right: binaural
recording (left and right channel)). Top: FFT (A-weighted) vs. time; bottom: Loudness according to ISO
532-1 vs. time
Experimental procedure
The participants were requested to assess environmental noise stimuli on a semantic differentialconsisting of eight 5-point category scales. The participants had to assess to what extent they agree ordisagree that the presented sound is perceived as pleasant, chaotic, vibrant, uneventful, calm, annoying,
eventful, and monotonous. The instruction and attributes were given in English in accordance to the
ISO/TS 12913-2. After a sound was terminated, the participants assessed their overall impressions
regarding the different attributes. To introduce the range of sounds, several sounds were presented firstfrom the set of stimuli without requesting any assessments. After the demonstration of several sounds,
a training sequence took place, where the participants familiarized with the evaluation tasks. They
were informed that the assessments of sound examples gained in this part of experiment will not beanalyzed.
Then, the first part of the experiment took place, where 16 sounds in total were sequentiallypresented and assessed by the participants. After a three minute break, 10 sound samples were
presented in the second part of the experiment, which had to be assessed on an 11-point category scalewith respect to the perceived level of ‘pleasantness’. The category scale was similar to the category
scale defined in the ISO/TS 15666 [7]. To reduce the importance of sequence effects, the order ofsounds was randomized. It was controlled that sounds recorded at the same place were separated by atleast three different stimuli.
Results
Figure 2 illustrates the assessments of the different environments recorded via a single microphoneor a binaural headset for two attributes ‘annoying’ and ‘pleasant’. In both cases, statisticallysignificant differences between assessments of the monaural and binaural playback were observed(annoying: F (1,240) =7.85, p<0.01, pleasant: F (1,240)=5.9, p<0.05) without any interaction effects.
The assessments of the remaining attributes showed differences as well, but these differences were6083

not statistically significant, but partially close to statistical significance (e.g. eventful: F (1,240)=
3.6, p=0.06).
Assessment of the attribute 'annoying'

5
4
3
2

BinauralMonaural

1
BerlinBreitscheidplatz

BerlinTiergarten

Köln DomNorth

Köln DomWest

London history
museumOsaka
Dotombori

Osaka Kansai
Sheffield
airporttownhall street

Assessment of the attribute 'pleasant'

5

4

3

2
BinauralMonaural

1
BerlinBreitscheidplatz

BerlinTiergarten

Köln DomNorth

Köln DomWest

London history
museumOsaka
Dotombori

Osaka Kansai
airportSheffield
townhall street

Figure 2 – Assessments (means and 95% confidence interval) of monaural and binaural noise stimuli
regarding the attributes “annoying” (top) and “pleasant” (bottom)
In subsequent interviews, the suitability of the used attributes was discussed. It turned out that
attributes like pleasant, annoying and eventful were judged to be highly appropriate, whereas
attributes like “vibrant” and “chaotic” were assessed as less appropriate. However, no attribute wasclassified as inappropriate.
Discussion
The presented experiment has shown, as expected, that the spatial hearing impression is importantwith respect to soundscape related assessments like ‘pleasant’ or ‘annoying’. I.e., the assessments ofacoustic environments differ between monaural and binaural reproductions. This observation supports
the specifications defined in the ISO/TS 12913-2. Because the majority of the participants did notindicate in a post-experimental interview that they noticed that they listened to the different locations
twice, in a monaural and binaural way, it is likely that the influence of potential demand characteristics
is not vitally important. Interestingly, in the ISO/TS 12913-2 attributes explicitly related to the spatial
auditory impression are not provided [8]. Potentially, such attributes might be relevant forcomprehensive investigations of soundscapes perception in particular in case of studying indoor
soundscapes.

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2.2 Measurements of human sensations, responses and outcomes
In the past a vast amount of methods and tools from multiple disciplines were applied to measure
perception of acoustic environments in context in order to meet the general holistic requirement of thesoundscape approach to understand sound perception in all its complexity . The diverse methods
range from bio-monitoring, questionnaires, interviews, mind mapping to observational studies or even
big data applications. The ISO/TS 12913-2 emphasizes the concept of soundscape as a holistic
approach and requests to investigate each soundscape situation from several viewpoints. According to
the ISO/TS 12913-2 this requires performing a soundwalk and/or a questionnaire and/or a guided
interview. Those methods are explicitly described and explained in the ISO/TS 12913-2.
Because the ISO/TS 12913-2 proposes different methods for data collection in the context ofhuman sensation and responses, a study using different proposed methods including rating scales fromthe ISO/TS 12913-2 compared the gained results. Based on repeated soundwalk measurements
performed in Aachen, it was observed that the results of the different rating scales aiming to explore
similar semantic dimensions (e.g. analogue scale with the attribute unpleasant compared to thediscrete ordinal scale with the attribute pleasant) correlate statistically significant in all cases ofsimilar attributes [9]. The correlation coefficients are shown in table 1. Moreover, it was observed thatboth scale types exhibit similar standard deviations [9]. However, in case of the analogue rating scales
the considered locations were judged as slightly more pleasant and less loud in average indicating theinevitable impact of the scale design and format on the respective results.
Table 1 – Correlation of assessments collected with selected rating scales from Method A and Method B
proposed in ISO/TS 12913-2
Rating scales (Method A – Method B)

Pearson correlation
coefficientpleasant (bipolar (agreement) discrete) vs. unpleasant (unipolar, analogue)-0.77**

annoying (bipolar (agreement), discrete) vs. unpleasant (unipolar, analogue)

0.65**

calm (bipolar (agreement), discrete) vs. loudness (unipolar, analogue)-0.76**

Interestingly, the results of the acoustical measurements performed during the repeated soundwalks
show similar results. By means of a 2-way ANOVA the effect of the factor “location” was compared tothe effect of the factor “repeated measurements”. Although both factors were statistically significant,the location factor related to acoustical differences between the eight considered locations (η²=0.4)
was much greater than the differences between the different soundwalks performed in 2010, 2011,2012 and 2015 (η²=0.06) [10].
This observation was supported by a canonical discriminant analysis, which as a cla ssification
analysis considered the results of the (psycho-) acoustic measurements. 25 different psychoacoustic
metrics of 64 recordings lasting three minutes were computed and used as input for the canonicaldiscriminant analysis. This analysis as a dimension-reduction technique intends to investigate whether
groups (locations) can be effectively separated by means of psychoacoustic metrics. In total, 62.5% ofcross-validated grouped cases were correctly classified. This means that meaningful data representing
the noise characteristics of a certain location can be collected by short-term measurements under
uncontrolled conditions. Interestingly, the determined function 1 correlates with the assessments of‘loudness’ and ‘annoyance’, whereas function 2 was more related to assessments of the attributes‘vibrant’ and ‘eventful’.

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Figure 3 – Result of a canonical discriminant analysis showing function 1 and function 2 using
psychoacoustic metrics of repeated measurements at eight different locations. The different colors represent
the different locations.
In general, based on the repeated soundwalks it was observed that independent from the usedmethod, whether method A or B, it is possible to collect reliable soundscape related data by means of
in-situ physical and perceptual measurements. As expected, if rating scales varying in design andformat are applied, different results are achieved. However, as table 1 illustrates, the results gained bydifferent methods described in ISO/TS 12913-2 and potential conclusions drawn are related to eachother to a certain extent. It is highly expected that due to the pub lication of the ISO/TS 12913-2
comparisons of the outcomes of the different defined methods will be subject to further research (forexample see [11, 12]). Such studies might help to identify the advantages and drawbacks of thedifferent proposed informative methods.

3. CONCLUSIONS
It is the general intent of the ISO 12913 series on soundscape to enable a broad international
consensus and to provide a foundation for communication across disciplines and professions with aninterest in soundscape. Due to the fact that the ISO 12913 documents are frequently quoted an impact
on soundscape studies and investigations can be assumed without doubt. The availability of the ISO
12913 documents has two major advantages: 1. Due to the extreme diversity of methods in soundscapeinvestigations in the past, a harmonized data collection process will increase the comparability ofstudies allowing the performance of meta-analyses and thus achieving a higher level of generality.
2. The possibility to reference to soundscape standards might increase the general acceptance of thesoundscape approach by authorities and decision-makers. An example might be the current noise
action plan in Wales [13]. The Welsh Government adopted a “Noise and soundscape action plan
2018-2023” with the intent to implement soundscape interventions in their noise action planning
process within the next years.
However, a remaining challenge is to translate the different methods, instructions, verbal labels
and attributes proposed in the ISO 12913 into different languages to be used internationally. A broadinternational application of the harmonized soundscape data collection methods and tools is only
possible, when validated translated versions of the ISO 12913 documents are available. First actions
determining translations representing the intended semantic dimensions described in ISO 12913 series
have shown the complexity of this translation task [14].
In general, it could be argued that the availability of standardized, uniform methods and tools
leading to an harmonization of the soundscape data collection process might impede further researchand endeavors with respect to development of advanced methods and tools to comprehensively
investigate the perception of acoustic environments. It is not unlikely that even more by defining a6086

(tentative) ground truth via an international standard/technical specification, further research is
provoked exploring the way humans perceive their (acoustic) environments by alternative, advanced
methods. There is always the possibility to compare study outcomes (measurement uncertainties, data
spread, effect sizes, etc.) based on alternative, improved methods to standard methods and tools.
Without a common agreement on methods such investigations are likely not to be performed on a large
scale. In particular, soundscape research needs more scientific evidence of its potential to promotehealth through cognitive restoration by designing urban environments [15]. It seems that the positive,
promotional effect on health needs to be further explored by advanced methods.

REFERENCES
1. To W M, Chung A, Vong I., Ip A. Opportunities for soundscape appraisal in Asia, Proc. Euronoise 2018,
May 2018, Crete, Greece 2018
2. ISO 12913-1. Acoustics. Soundscape, Part 1: Definition and conceptual framework, International
Standardization Organization, Geneva, Switzerland, 2014
3. Botteldooren D, Andringa T, Aspuru I, Brown AL, Dubois D, Guastavino C, Kang J, Lavandier C,
Nilsson M, Preis A, Schulte-Fortkamp B. From sonic environment to soundscape, In: Kang J,
Schulte-Fortkamp B (ed.). Soundscape and the built environment, CRC Press, Taylor and Francis Group,
Boca Raton, 2016
4. ISO/TS 12913-2. Data collection and reporting requirements, International Standardization
Organization, Geneva, Switzerland, 2018
5. Hong JY, He J, Lam B, Gupta R, Gan WS. Spatial Audio for Soundscape Design: Recording andReproduction, Applied Sciences, June 2017, 2017
6. ISO 532-1:2017: Acoustics. Methods for calculating loudness. Part 1: Zwicker method, International
Standardization Organization, Geneva, Switzerland, 2017
7. ISO/TS 15666:2003: Acoustics. Assessment of noise annoyance by means of social and socio-acoustic
surveys, International Standardization Organization, Geneva, Switzerland, 2003
8. Fiebig A, Yang M. Implikationen verschiedener Aufnahmetechnologien zur Untersuchung vonUmgebungsgeräuschen, Proc. DAGA 2019, Rostock, Germany, 2019
9. Fiebig A. Recent developments in the standardization of soundscape, Proc. Internoise 2018, Chicago,
USA, 2018
10. Fiebig A. Reliability of in-situ measurements of acoustic environments, Proc. DAGA 2016, Aachen,
Germany, 2016
11. Aletta F, Guattari C, Evangelisti L, Asdrubali F, Oberman T, Kang J. Exploring the compatibility of“Method A” and “Method B” data collection protocols reported in the ISO/TS 12913-2:2018 for urban
soundscape via a soundwalk, Applied Acoustics, May 201912. Heggie C, Smyrnova J, Smith B, Allen M, Klein A. The practicalities of soundscape data collection bysystematic approach according to ISO 12913-2, Proc. Internoise 2019, Madrid, Spain, 2019
13. Welsh government. Noise and soundscape action plan 2018-2023, OCL, Crown, ISBN: 978 1 78964
365 7, 201814. Jeon JY, Hong JY, Lavandier C, Lafon J, Axelsson Ö, Hurtig M. A cross-national comparison inassessment of urban park soundscapes in France, Korea, and Sweden through laboratory experiments.
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Genuit K, Fiebig A, Bento Coelho JL, Maffei L, Lavia L. Ten questions on the soundscapes of the built
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