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Auditory masking of wanted and unwanted sounds in a city park
Stockholm University, Faculty of Social Sciences, Department of Psychology.
Stockholm University, Faculty of Social Sciences, Department of Psychology.
Stockholm University, Faculty of Social Sciences, Department of Psychology.
2010 (English)In: Noise Control Engineering Journal, ISSN 0736-2501, E-ISSN 2168-8710, Vol. 58, no 5, 524-531 p.Article in journal (Refereed) Published
Abstract [en]

Auditory masking of unwanted sounds by wanted sounds has been suggested as a tool for outdoor acoustic design. Anecdotal evidence exists for successful applications, for instance the use of fountain sounds for masking road traffic noise in urban parks. However, basic research on auditory masking of environmental sounds is lacking. Therefore, we conducted two listening experiments, using binaural recordings from a city park in Stockholm exposed to traffic noise from a main road and sound from a large fountain located in the center of the park. In the first experiment, 17 listeners assessed the loudness of the road traffic noise and fountain sounds from recordings at various distances from the road, with or without the fountain turned on. In the second experiment, 16 listeners assessed the loudness of systematic combinations of a singular fountain sound and a singular road traffic noise. The results of the first experiment showed that the fountain sound reduced the loudness of road traffic noise close to the fountain, and that the fountain sound was equally loud or louder than the road traffic noise in a region 20-30 m around the fountain. This suggests that the fountain added to the quality of the city park soundscape by reducing the loudness of the (presumably unwanted) traffic noise. On the other hand, results from the second experiment showed that road traffic noise was harder to mask than fountain sound, and that the partial loudness of both sources was considerably less than expected from a model of energetic masking. This indicates that auditory processes, possibly related to target-masker confusion, may reduce the overall masking effect of environmental sounds.

Place, publisher, year, edition, pages
2010. Vol. 58, no 5, 524-531 p.
National Category
Fluid Mechanics and Acoustics Psychology
Research subject
Psychology
Identifiers
URN: urn:nbn:se:su:diva-51238DOI: 10.3397/1.3484182ISI: 000285049400007OAI: oai:DiVA.org:su-51238DiVA: diva2:387740
Note

authorCount :4

 

Available from: 2011-01-14 Created: 2011-01-10 Last updated: 2017-12-11Bibliographically approved
In thesis
1. Perspectives on wanted and unwanted sounds in outdoor environments: Studies of masking, stress recovery, and speech intelligibility
Open this publication in new window or tab >>Perspectives on wanted and unwanted sounds in outdoor environments: Studies of masking, stress recovery, and speech intelligibility
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

An acoustic environment contains sounds from various sound sources, some generally perceived as wanted, others as unwanted. This thesis examines the effects of wanted and unwanted sounds in acoustic environments, with regard to masking, stress recovery, and speech intelligibility.

In urban settings, masking of unwanted sounds by sounds from water structures has been suggested as a way to improve the acoustic environment. However, Study I showed that the unwanted (road traffic) sound was better at masking the wanted (water) sound than vice versa, thus indicating that masking of unwanted sounds with sounds from water structures may prove difficult. Also, predictions by a partial loudness model of the auditory periphery overestimated the effect of masking, indicating that centrally located informational masking processes contribute to the effect. Some environments have also been shown to impair stress recovery; however studies using only auditory stimuli is lacking. Study II showed that a wanted (nature) sound improve stress recovery compared to unwanted (road traffic, ambient) sounds. This suggests that the acoustic environment influences stress recovery and that wanted sounds may facilitate stress recovery compared to unwanted sounds. An additional effect of unwanted sounds is impeded speech communication, commonly measured with speech intelligibility models. Study III showed that speech intelligibility starts to be negatively affected when the unwanted (aircraft sound) masker have equal or higher sound pressure level as the speech sound. Three models of speech intelligibility (speech intelligibility index, partial loudness and signal–to–noise ratio) predicted this effect well, with a slight disadvantage for the signal–to–noise ratio model. Together, Study I and III suggests that the partial loudness model is useful for determining effects of wanted and unwanted sounds in outdoor acoustic environments where variations in sound pressure level are large. But, in environments with large variations in other sound characteristics, models containing predictions of central processes would likely produce better results.

The thesis concludes that wanted and unwanted characteristics of sounds in acoustic environments affect masking, stress recovery, and speech intelligibility, and that auditory perception models can predict these effects.

Place, publisher, year, edition, pages
Stockholm: Department of Psychology, Stockholm University, 2013. 55 p.
National Category
Psychology (excluding Applied Psychology)
Research subject
Psychology
Identifiers
urn:nbn:se:su:diva-95661 (URN)978-91-7447-807-5 (ISBN)
Public defence
2013-12-18, David Magnussonsalen (U31), Frescati Hagväg 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defence the following paper was unpublished and has a status as follows: Paper 3: Manuscript

Available from: 2013-11-26 Created: 2013-10-31 Last updated: 2013-11-11Bibliographically approved
2. Unwanted wanted sounds: Perception of sounds from water structures in urban soundscapes
Open this publication in new window or tab >>Unwanted wanted sounds: Perception of sounds from water structures in urban soundscapes
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Water structures, for example, fountains, are common design elements in urban open public spaces. Their popularity is probably explained by their visual attractiveness. Less is known about how the sounds of water struc-tures influence the urban soundscape. This thesis explores the potential ef-fects of water sounds on urban soundscapes based on the character of water sounds. Three psychoacoustic studies were conducted in which listeners rated the perceptual properties of various water sounds. Study I found that water sounds had a limited ability to mask traffic noise, as the frequency composition of the sounds resulted in road-traffic noise masking fountain sounds more than the reverse. A partial loudness model of peripheral audito-ry processes overestimated the observed masking effect of water sound on road-traffic noise, and it was suggested that this was related to central pro-cesses, in particular, target/masker confusion. In Study II, water sounds of different degrees of perceived pleasantness were mixed with road-traffic noise to explore the overall effect on soundscape quality. The overall pleas-antness was increased substantially by adding a highly pleasant water sound; however, less pleasant water sounds had no effect or even reduced overall pleasantness. This result suggests that the perceptual properties of water-generated sounds should be taken into consideration in soundscape design. In Study III, this was explored by analyzing a large set of recordings of sounds of water fountains in urban open spaces. A multidimensional scaling analysis of similarity sortings of sounds revealed distinct groups of percep-tually different fountain sounds. The group of pleasant fountain sounds was characterized by relatively low loudness and high fluctuation strength and tonality, generating purling and rippling sounds. The group of unpleasant fountain sounds was characterized by high loudness and low fluctuation strength and tonality, generating a steady-state like noisy sound.. A joint result of all three studies is that sounds from water structures with a high flow rate (i.e., a large jet and basin in Study I, a waterfall in Study II, and large fountains in Study III) generating a steady-state noisy sound should be avoided in soundscape design. Instead, soundscape design might better focus on more fluctuating water sounds, which were considered more pleasant in both studies II and III. A general conclusion from this thesis is that water-generated sounds may be used to improve the soundscape, but that great care must be taken in selecting the type of water sound to use.

Place, publisher, year, edition, pages
Stockholm: Department of Psychology, Stockholm University, 2015. 81 p.
Keyword
Perception, psychoacoustics, soundscape, water-sound
National Category
Psychology
Research subject
Psychology
Identifiers
urn:nbn:se:su:diva-119362 (URN)978-91-7649-235-2 (ISBN)
Public defence
2015-09-25, David Magnussonsalen (U31), Frescati Hagväg 8, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.

Available from: 2015-09-03 Created: 2015-08-06 Last updated: 2015-09-01Bibliographically approved

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