SOUNDSCAPE: AN APPROACH TO RELY ON HUMAN ... - …Brooks Acoustics Corporation Vernon, Connecticut 06066 Wade R. Bray HEAD acoustics, Inc. ... adequately the circumstances of everyday

Soundscape and Community Noise 7

SOUNDSCAPE: AN APPROACH TO RELY ON HUMAN PERCEPTION AND EXPERTISE

IN THE POST-MODERN COMMUNITY NOISE ERABrigitte Schulte-Fortkamp

Institute of Technical Acoustics, Technical University BerlinBerlin, Germany

Bennett M. BrooksBrooks Acoustics CorporationVernon, Connecticut 06066

Wade R. BrayHEAD acoustics, Inc.

Brighton, Michigan 48116

The term “Soundscape” seems likemagic compared with standardmeasurement methods in com-

munity noise, since it considers people’sminds as measuring instruments hav-ing the same relevance as “real” meas-urements. However, even in the 1970s,Murray Schafer’s message about noise-abatement legislation brought aware-ness of the necessity and opportunity toconsider not just noise alone, but alsoits perception by the experts who areaffected by noise: those who live in thesoundscapes—a term Schafer coined.He clearly stated, “early noise abate-ment legislation was selective and qual-itative, contrasting with that of themodern era, which has begun to fixquantitative limits in decibels for allsounds…the study of noise legislationis interesting, not because anything is ever really accom-plished by it, rather because it provides us with a concreteregister of acoustic phobias and nuisances. Changes in leg-islation give us clues to changing attitudes and perceptions,and these are important for the accurate treatment ofsound symbolism.” 1

During the past 30 years, advances in policy develop-ment include the introduction of community-based environ-mental protection. This process makes the locally-affectedcommunity a major stakeholder in the crafting of effectivepublic policy. The techniques of Soundscape are ideally suit-ed for the development of community-based noise policy.

After consensus had been reached about the EuropeanUnion (EU)-directive on environmental noise in 2002,there remain several major challenges to overcome:

(1) Presently, only the effects of a single noise sourceare assessed, while typically several sound sources arepresent simultaneously. (2) Only mono-sensory sound perception is taken intoaccount, while in reality other sensory qualities (e.g.,visual or very low frequency vibrations) contribute.(3) On the basis of the present standards, it is not yetpossible to predict the effects of changes in the urban

soundscape—difficult because data areonly valid for “steady-state” condi-tions. (4) It will become necessary to makegeneralizations—but there are verysubstantial differences in context.(5) Presently, noise mapping is state ofthe art—but what is really needed issome form of annoyance mapping.

For more than ten years the multi-disciplinary approach has been appliedto the study of community noise toexplain people’s reaction to noise,including context related evaluation.The context-bounded approach wasthe crucial step to reach the definitionof “Soundscape,” using its fundamentalknowledge and procedures.

The soundscape approach providesa method to develop acoustical indica-

tors and parameters into a database that describes urban andother outdoor living areas with respect to their physical con-ditions and their relevance for life. Those parameters will reli-ably allow the measurement of outdoor sound quality, whichwill take into consideration not only the sound pressure butalso the characteristics of the sounds which lead to specifichuman reactions, both positive and negative: calmness, inspi-ration, annoyance, discontentment, anxiety, etc. as well as thepathogenic effects. Emission and immission measurementsmust be performed to document the physical conditions ofthe examined living area. In particular, the contribution ofimportant sources like traffic noise to the overall sound expo-sure and its influence on the evaluations by residents must bedetermined. Moreover, the question is, to which degree doesa single source determine the soundscape of the environmentwith respect to perception and evaluation? Therefore, diverseboundary conditions should be taken into account to reflectadequately the circumstances of everyday life.

The application of Soundscape in community noise israpidly evolving, and has been discussed at numerousrecent conferences within the Acoustical Society ofAmerica (ASA), and at a workshop on methods for com-munity noise and annoyance evaluation held at the149th

“The soundscape approach

provides a method to develop

acoustical indicators and

parameters into a database

that describes urban and

other outdoor living areas

with respect to their physical

conditions and their

relevance for life.”

8 Acoustics Today, January 2007

ASA meeting in Vancouver, Canada on May 16, 2005.Areas identified for further development at this workshopincluded: economics/noise policy-standards, combinedeffects, common protocols/cross cultural studies and edu-cation about soundscape. Other areas identified include:improve combined measurement procedures: qualitativeand quantitative parameters—including the character ofsounds and cross-cultural questionnaires. The importanceof survey site selection was emphasized. The combinedsoundscape approach requires that physical noise criteriamatch qualitative descriptors. There is a need to correlatecomplaint language with metrics for policy, and to intro-duce the qualitative methods of psychology and sociologyto engineering analysis, combining quantitative and qual-itative tools for land use planning. Soundscape analysisshould place sound in context, with noise and soundlinked to activity at realistic study sites. We must distin-guish the totality of soundscape from the limited idea of aquiet zone. The connection between research and designfor communities is a creative process. To complete thisconnection we need methods to: measure and identifydesign values, develop a lexicon of qualities/values forsoundscape design, investigate a subject’s control/non-control over the environment, understand the motivationof people to choose a particular environment, and createsoundscape simulations of proposed sites for evaluation byofficials and the public. Continuing soundscape researchshould provide practical data that can be applied bydesigners to create pleasing acoustical environments.

This article describes a range of measures and solu-tions needed to identify an integrated model todesign/improve soundscapes and enhance urban planningconcepts. Of course, we are aware that these are early stepsand scientific and applied work is still to be done.2

Community noise assessment is an increasinglyimportant means by which to improve the quality of mod-ern life, particularly in urban outdoor settings. The effectsthat community noise has on residents, businesses andother stakeholders must be assessed accurately to createthe political and cultural climate needed to positivelyaffect the environmental soundscapes. This climateincludes an effective policy structure which recognizes theimpacts of sound on the community, planning, and designprinciples which can be applied to specific projects andsettings.

Soundscape analysis combines the physical measure-ment of sound with a scientific investigation and evalua-tion of the community perception of sound. The methodsof soundscape analysis can provide the practical tools forachieving beneficial results in outdoor sound qualitythrough the application of thoughtful community noisepolicy, environmental planning, and design.3–6

Combining physical, psychoacoustical, and perceptu-al measurements

In the context of community noise, there is a commonconsent about the necessity of additional parameters besidethe A-weighted sound pressure level (SPL). The A-weight-ed and energy-equivalent Intensity Level (IL) and loudness

measurements are not sufficient for understanding humanperception or for adequate description of an urban sound-scape. Essentially, the introduction of new parameters, themore sophisticated use of existing parameters, and amerged approach from different measurement proceduresappear to be inevitable.

Physical and psychoacoustical measurementsThe physical measurement of relevant acoustical

parameters in an outdoor setting is a requisite first step inevaluating that environment. These methods of measure-ment and analysis are becoming increasingly sophisticated.They range from the simple measurement of overall A-weighted level samples, time histories, statistical and spec-tral analyses, through the compilation of time-variantZwicker loudness tableaus and further psychoacousticevaluation and analysis.

Therefore, psychoacoustic parameters should beapplied to measure and assess environmental sound moreproperly. With the help of psychoacoustic parameters thatare mainly based on standardized procedures of measure-ment and analysis, it may be possible to explain why someenvironmental sound sources are more annoying—orpleasing—than others.

Relating human hearing and objective measurementHuman hearing differs in many fascinating (and

sometimes frustrating) ways from conventional acousticmeasurement devices and processes. It is spatially- andpattern-sensitive, easily detecting small changes in itssonic “surroundings” in any combination of level, location(including movement), time or frequency. A physicallysmall source in a context of sounds coming from manydirections can dominate attention by fluctuating and/ormoving, even though its power contribution is a smallfraction of the whole.7 Consider the visual analogy of driv-ing at dusk and distinctly noting the flashing LED taillightof a bicycle in the moderate distance—a pattern drawingyour attention—and its significance (a “human weight-ing”). Were the light not flashing, the chances are that youwould not have noticed it until getting much closer. Evenin low dusk, its energy contribution to the scene is tiny, yetit is readily recognized. Such fluent and situation-depend-ent signal processing and weighting by the “human meas-uring system” challenges the selection of appropriate tech-nical methods to quantify sound situations and theirobjective significance in soundscapes.

Some options for matching measurements with per-ceptions include levels and spectra versus time, rather thanoverall A-weighted Leq, which are valuable in soundscapemeasurement. Note, Leq is not representative of the subjec-tive impression and contextual evaluation.

Psychoacoustic measures versus time—loudness,sharpness (essentially the ratio of high-frequency loudnessto overall loudness), roughness (quick fluctuation), fluctu-ation strength (slow fluctuation) and others, overall andversus frequency, generally represent subjective auditoryevaluations better than conventional level-based measure-ments.

Perceptual measurementsThe key to understanding, and ultimately to applying

these physical measurements, is an evaluation of the per-ceptual effects induced by the various magnitudes of thosespecific physical and psychoacoustic parameters.8 Sincesoundscapes have to be considered as two-componentenvironments, comprising certain sound sources as well asthe way people feel about those sounds contributing to theidentity of those residential areas, these essential “humanweighting” effects may be analyzed through the use of sci-entifically-developed interviews, questionnaires and othermeans to determine the frank and honest appraisal bycommunity members of their sound environment.4 Onlythrough the accurate evaluation of this cause-and-effectrelationship may successful strategies be developed andimplemented. It is important to recognize that amongvarying soundscape types the relationship between physi-cal and perceptual parameters will have similarities, butthe relationship will also have unique properties tied toeach specific community and living context, related tosocio-economic background and specific lifestyle.

For example, the contextual conditions are importantwhen people are evaluating noise annoyance. The combi-nation of methods with different sensibilities for subjects’work during a process of perceiving, describing and/orevaluating noise in such an environment is necessary for areliable and valid analysis and interpretation of data.

Another aspect is that the annoyance of exposed indi-viduals rises with increasing traffic density. In a situationwith low traffic density, single noise events stand out. Thisresults in a high level of annoyance although the Leq is low.These parameters must be adequately considered in meas-urements. The broad approach using acoustical diariesand both indoor and outdoor measurements guarantees


the identification of the relevant indicators that have anessential impact on the perception and evaluation of envi-ronmental noise.9,10

“Soundscaping”—Combined soundscape analysistechnique

“Acoustic coloration” from the environmental soundsources carries information that may either block or stim-ulate human activities, thoughts, and feelings. Therefore,soundscape evaluation will include acoustical as well asother sensory, aesthetic, geographic, social, psychological,and cultural modalities in the context of human activity.The aim is to get access to the social, psychological, andcultural conditions that are important to determine a par-ticular individual’s and/or collective behavior, attitudes,and emotions relative to the given noise under scrutiny.

In daily life, parameters and phenomena enter intointerrelation and interaction that can be investigated withregard to their acoustic-ecological, psycho-acoustic, socio-acoustic ascription. Detailed analysis of the typology, mor-phology, and topology of potential test sites must include,criteria like land use and function, urban fabric and itsstate or condition, qualities of private, semi-private andpublic zones, analysis of neighborhoods in terms of archi-tectural shape and scale, specific issues of any existing sitedevelopment strategies, and specific features related to thesite, i.e. differentiating patterns and situations.

Soundscapes are defined with respect to their scope. Thiscan be done by sound walks that are participatory sound andlistening walks with respect to the acoustical, visual, aesthet-ic, geographic, social, and cultural modalities.

Data collection—Short term A brief demonstration of the combined soundscape

analysis technique (“Soundscaping”) was given at the 151stMeeting of the Acoustical Society of America, inProvidence, Rhode Island, June 2006.11 During a walk inthe urban area near the meeting hotel, physical soundmeasurements and perceptual interviews were conductedat two downtown locations. Both of these locations wereclose to office and shopping destinations.

One location is known as the “Riverwalk.” This river-side area is popular with residents of the city and the sur-rounding communities for its attractive setting and for itsfamous Saturday night event “Waterfire,” which is heldthroughout the summer months. In this event, fires arebuilt and displayed in a series of metal stanchions placed inthe river and the surrounding plazas are alive with music,food and other entertainment.

Measurement and interviewsFor this soundscaping demonstration, measurements

and interviews were conducted during an afternoon of fairweather, while the Riverwalk Plaza was busy with lunchhour pedestrian traffic (see Fig. 2). Although the soundlevel in dB (A) was consistently in the mid 60’s, with high-er excursions due to nearby construction activity, the reac-tion of pedestrians to the sound was universally positive.This was primarily due to their positive personal associa-

Fig. 1. Possible relationships linking sound pressure level (vertical, dB(A)) to psy-choacoustic loudness (horizontal, the linear measure Sone) depend on spectralshape (there is no single rule). The inner ear, assigning frequencies to locations ofhair-cell excitation along a physical structure (much different than the way amicrophone works), responds as loudness to the total area being excited. For exam-ple, tonal centers close together have merged excitation areas and generate lowerloudness than tonal centers more separated in frequency, for the same sound pres-sure level. Another major factor in loudness sensation: for constant sound pressurelevel vs. frequency, loudness is much higher (approximately double)—around 4kHz due to a strong acoustic resonance of the outer ear near the ear canal entrance.

tions for the area with the enjoyable “Waterfire” activities.The soundscape analysis of the second location, the

large lawn between the Rhode Island State House and theTrain Station, yielded similar results (see Figs. 3-7). Again,


Fig. 2. Riverfront walk

Photos: Riverfront walk

despite the relatively high incursions of noise from passingvehicles, particularly city buses, the area was well-liked bycommunity members for its attractive expanses of greeneryand dignified buildings.

Fig. 4. Halfway up theState House lawn, “look-ing” toward the TrainStation, a bus pass eventbetween approximately1:12 p.m. and 1:13 p.m.Level vs. time over about65 seconds, left ear of arti-ficial head, unweighted(blue) and A-weighted(red). The time resolutionof measurements can beimportant. Left: Slow timeweighting (1-second inte-gration). Middle: Fastweighting (125 ms). Right:2 ms, similar to humanauditory integration timefor short-duration events.The average values arealso given. The three peaksto the right of the bus eventare due to a pile driver sev-eral blocks away.


Figure 3: State House lawn and Train Station


Fig. 5. Same data, psychoacoustic measures: overall loudness vs. time in the unit Sone (blue, right scale) and sharpness vs. time in acum (red, left scale). As the buspassed, its engine fan noise was rapidly masked and unmasked by parked cars and the spaces between them, producing a rhythmic whooshing sound.

Fig. 6. Specific loudness (spectrum of loudness) vs. time. The vertical axis represents frequency and the color scale represents loudness. Note that the highest loudnessoccurred roughly between 30 and 300 Hz, and that the region around 4 kHz has a higher loudness than at nearby frequencies. The ear discriminates by frequency andcan often detect simultaneously a relatively low-loudness event at a different frequency than a higher-loudness event. Specific loudness vs. time can show this, in caseswhere overall loudness measurement masks the effect.


Data collection—Long termSoundscaping may be undertaken as a complete study

with long-term, detailed measurements of physical acousti-cal parameters, and comprehensive attitudinal surveys.Brief preliminary results may be obtained through the useof local police or other public workers, who are assigned toobtain short sound level samples and activity observations,along with personal assessments, during their normal dailyrounds in the community.3,6 A typical form for this type ofpreliminary survey is shown below.

The “Soundscape Approach,” understood as a qualita-tive-quantitative methodology, has been applied recently inseveral field studies. Empirically, the perception of sounds

and their evaluation were explored under the premise ofcombining human judgment and physical factors. In thosefield studies, the environmental noise perception and eval-uation in a defined urban area were investigated in detail.For that reason, open, narrative, but issue-centred inter-views with residents were carried out, and those interviewsallowed the interviewed persons to set their own focus oncertain aspects. The interviews are the basis for the subject-centered categorization.2–6,9

The qualitative data analysis shows that the soundevaluations depend on the social and cultural structures inwhich the individual is embedded. Therefore, the socio-cultural frame of reference, which the sound-exposed per-

Fig. 7. Human hearing discriminates low-frequency tones, such as the engine orders of the passing bus. In addition to the psychoacoustic and level-based measures, aspectrum vs. time measurement with good frequency resolution at low frequencies, such as this variable-frequency-resolution (VFR) analysis, proves useful. The verti-cal axis is frequency and the color axis represents sound pressure level in B-weighted dB.


son uses automatically as a criterion for orientation andevaluation, must be explored in detail. Especially, a collec-tive feeling of identity has a major impact on the expectan-cies and claims people have concerning their sound envi-ronment.3–10

SummaryThe combination of physical and psycho-acoustical

measurements with scientific evaluation of perceptualresponses to environmental noise, known asSoundscaping, is an essential method for assessing andactualizing environments. Determining the properties ofthe soundscape which lead to specific human emotions(e.g. calmness, annoyance, discontentment, anxiety, etc.,besides the pathogenic effects) will go far beyond measur-ing the sound pressure alone. For those reasons, differenttypes of data (qualitative and quantitative) must be com-pared and combined. Interviews with exposed people willhighlight the data acquisition to consider all the objectiveand subjective dimensions that are relevant in the contextof soundscapes.

Therefore, diverse boundary conditions have to betaken into account to reflect adequately the circumstancesof everyday life. By means of the newly-defined parame-ters, it will be possible to propose a range of measures andsolutions that can be integrated in models for improvingurban soundscapes and urban planning concepts.

One more remarkDuring the past 10 years in “Soundscape and

Community Noise” there has been much research done andknowledge gained about sonic environments related todaily life and lifestyle. But, as Mike Stinson pointed out inhis recent overview on noise in Acoustics Today, Vol. 2, July2006: “We’re not done yet!”

As we seek to develop and refine the methods ofSoundscaping further the following actions are needed:

• Cataloging correlations between physical parame-ters and perceptual responses

• Standardizing a terminology lexicon of soundscapedescriptors

• Standardizing measurement procedures• Listing recommendations for perceptual evaluation

and analysis• Setting up an international working group on

Soundscapes AT

References1 R. M. Schafer, The Soundscape, Our sonic environment and the

tuning of the world (Destiny Books, Rochester, Vermont,1977).

2 B. Schulte-Fortkamp and D. Dubois (guest editors), “Recentadvances Soundscape research,” special issue of Acta Acusticaunited with Acustica 92 (6), v-viii (2006).

3 B. M. Brooks, “Community design with soundscape in mind,”J. Acoust. Soc. Am. 117(4), 2551 (A) (2005).

4 B. M. Brooks, “Traditional measurement methods for charac-terizing soundscapes.” J. Acoust. Soc. Am. 119(5), 3260 (A)(2006).

5 A. Fiebig and B. Schulte-Fortkamp, “Techniques of analysisand their applicability in the context of community noise,” J.Acoust. Soc. Am. 117(4) 2592(A) (2005).

6 B. Schulte-Fortkamp and A. Fiebig, “Soundscape analysis in aresidential area: An evaluation of noise and people’s mind,”Acta Acustica united with Acustica 92(6), 875–880 (2006).

7 K. Genuit, and W.R. Bray, “Soundscape Measurement andAnalysis,” J. Acoust. Soc. Am. 119(5) 3260(A) (2006).

8 W. R. Bray, “Relationships of Loudness, Level and TimeStructure in Pipe Organ Registration and Design,” J. Acoust.Soc. Am. 115(5), 2453(A) (2004).

9 B. Schulte-Fortkamp and K. Genuit, “The acoustical diary asan innovative tool in soundscape evaluation,” J. Acoust. Soc.Am. 115(5) 2496(A) (2004).

10 B. Schulte-Fortkamp and A. Fiebig, “The daily rhythm ofsoundscape,” J. Acoust. Soc. Am. 120(5), 3238(A) (2006).

11 B. Brooks and B. Schulte-Fortkamp, “Soundscape: anapproach to combine physical measures and subjective evalu-ation with respect to community noise assessment,”Proceedings of Internoise, Honolulu, Hawaii (2006).


Wade R. Bray’s morethan 30 years of expe-rience include auto-motive sound quality,musical instruments,churches and per-forming arts venues,theatre sound systemand electroacousticenhancement systemdesign, and loud-speaker and telecon-

ference acoustics. He has participated in the North Americanactivities of HEAD acoustics GmbH of Herzogenrath,Germany since 1987, serving as Vice President and chieftechnical officer of HEAD acoustics, Inc., Brighton,Michigan. In the 1980s, as a senior consultant at JaffeAcoustics, Inc., his work centered on electronic variableacoustic systems and full duplex concealed audio teleconfer-encing systems.

He earned degrees in English and Physics at ArizonaState University with additional studies in psychology andmusic. He is a member of the Acoustical Society of America,Society of Automotive Engineers and Audio EngineeringSociety, and is an Associate of the Institute of Noise ControlEngineering (INCE). As a hobby, he is house organist at theMichigan Theatre in Ann Arbor.

Brigitte Schulte-Fortkamp is aProfessor at theT e c h n i c a lUniversity Berlin,Germany. For over20 years, herresearch activitieshave been con-cerned with assess-ing transportationnoise related to

annoyance and quality of life from an interdisciplinary point ofview. She is particularly interested in evaluation of soundscapesby means of psychoacoustics, acoustic ecology, and person-environment-fit approaches. Her research concentrates not onlyon the impact of noise on sensitive groups such as noise sensi-tive people but also with comfort-related issues concerningdefined acoustical environments. She is a fellow of theAcoustical Society of America, Associate Editor of JASA forNoise, and Chair of the Noise Technical Committee.

Bennett M. Brooks hasbeen the President ofBrooks AcousticsCorporation since1992. He began hiscareer at NASA and con-tinued in the aerospaceindustry. In 1989, heentered engineering pri-vate practice with UnitedAcoustic Consultants.His projects include cre-

ating pleasing sound environments and noise control solutionsfor applications ranging from concert halls, schools, churches,recording studios, commercial offices and aircraft interiors tofactories, and power facilities. He has also developed quietproducts for major manufacturers and noise policy for stateand local governments. Current project interests include thosein the architectural, legal, industrial research, community noise,and musical fields. He received a B.S. in MechanicalEngineering from the Massachusetts Institute of Technology(1974) and an M.S. in Acoustics from the George WashingtonUniversity (1977). He is a licensed Professional Engineer (P.E.),a fellow of the Acoustical Society of America, a member of theInstitute of Noise Control Engineering (INCE) and an officer ofthe National Council of Acoustical Consultants (NCAC).

SOUNDSCAPE: AN APPROACH TO RELY ON HUMAN ... - …Brooks Acoustics Corporation Vernon, Connecticut 06066 Wade R. Bray HEAD acoustics, Inc. ... adequately the circumstances of everyday

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