| 1. |
- Braat-Eggen, Ella, et al.
(författare)
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Auditory distraction in open-plan study environments : Effects of background speech and reverberation time on a collaboration task
- 2019
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Ingår i: Applied Acoustics. - : Elsevier. - 0003-682X .- 1872-910X. ; 154, s. 148-160
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Tidskriftsartikel (refereegranskat)abstract
- Previous research has shown that semantic-based tasks are negatively influenced by semantic aspects in background speech. Collaboration is an important task in open-plan study environments and is a semantic task which might be disrupted by background speech. Therefore, the aim of this study was to analyze the influence of irrelevant background speech on student-collaboration. Participants worked in pairs to solve spot-the-difference puzzles, by using the 'DiapixUK' collaboration task, while they were exposed to different background sound scenarios. The composed sound scenarios varied in semantic content (mother tongue and foreign language background speech)and reverberation time (short vs long), the latter affecting speech intelligibility. Although a longer reverberation time decreases the intelligibility of background speech and a foreign language decreases meaningfulness of speech, no significant changes in performance were found. On the other hand, the data show an increased perceived disturbance for a longer reverberation time, which we interpret as an increased difficulty of interpersonal communication in the collaboration task due to the increased level of the background speech. The quiet reference condition was the most preferred sound condition which is in line with both the effect of a low background sound level and the absence of semantic interference.
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| 2. |
- Forssén, Jens, et al.
(författare)
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A model of sound scattering by atmospheric turbulence for use in noise mapping calculations
- 2014
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Ingår i: Acta Acoustica united with Acustica. - : S. Hirzel Verlag. - 1610-1928 .- 1861-9959. ; 100:5, s. 810-815
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Tidskriftsartikel (refereegranskat)abstract
- Sound scattering due to atmospheric turbulence limits the noise reduction in shielded areas. An engineering model is presented, aimed to predict the scattered level for general noise mapping purposes including sound propagation between urban canyons. Energy based single scattering for homogeneous and isotropic turbulence following the Kolmogorov model is assumed as a starting point and a saturation based on the von Kármán model is used as a first-order multiple scattering approximation. For a single shielding obstacle the scattering model is used to calculate a large dataset as function of the effective height of the shielding obstacle and its distances to source and receiver. A parameterisation of the dataset is used when calculating the influence of single or double canyons, including standardised air attenuation rates as well as façade absorption and Fresnel weighting of the multiple façade reflections. Assuming a single point source, an aver aging over three receiver positions and that each ground reflection causes energy doubling, the final engineering model is formulated as a scattered level for a shielding building without canyon plus a correction term for the effect of a single or a double canyon, assuming a flat rooftop of the shielding building. Input parameters are, in addition to geometry and sound frequency, the strengths of velocity and temperature turbulence.
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| 3. |
- Forssén, Jens, 1968, et al.
(författare)
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A Model of Sound Scattering by Atmospheric Turbulence for Use in Noise Mapping Calculations
- 2014
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Ingår i: Acta Acustica united with Acustica. - : Wissenschaftliche Verlagsgesellschaft mbH. - 1610-1928 .- 1861-9959. ; 100:5, s. 810-815
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Tidskriftsartikel (refereegranskat)abstract
- Sound scattering due to atmospheric turbulence limits the noise reduction in shielded areas. An engineering model is presented, aimed to predict the scattered level for general noise mapping purposes including sound propagation between urban canyons. Energy based single scattering for homogeneous and isotropic turbulence following the Kolmogorov model is assumed as a starting point and a saturation based on the von Karman model is used as a first-order multiple scattering approximation. For a single shielding obstacle the scattering model is used to calculate a large dataset as function of the effective height of the shielding obstacle and its distances to source and receiver. A parameterisation of the dataset is used when calculating the influence of single or double canyons, including standardised air attenuation rates as well as facade absorption and Fresnel weighting of the multiple facade reflections. Assuming a single point source, an aver aging over three receiver positions and that each ground reflection causes energy doubling, the final engineering model is formulated as a scattered level for a shielding building without canyon plus a correction term for the effect of a single or a double canyon, assuming a flat rooftop of the shielding building. Input parameters are, in addition to geometry and sound frequency, the strengths of velocity and temperature turbulence.
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| 4. |
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| 5. |
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| 6. |
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| 7. |
- Forssén, Jens, 1968, et al.
(författare)
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Statistics of A-weighted road traffic noise levels in shielded urban areas
- 2006
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Ingår i: Acta Acustica united with Acustica. - 1610-1928 .- 1861-9959. ; 92:6, s. 998-1008
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Tidskriftsartikel (refereegranskat)abstract
- In the context of community noise and its negative effects, the noise descriptors used are usually long-term equivalent levels and, sometimes, maximum levels. An improved description could be achieved by including the time variations of the noise. Here, the time variations of A-weighted road traffic noise levels have been studied. Of special interest are situations with a shielded courtyard. For numerical results, a ray model has been used for calculating the sound propagation, and the traffic has been modelled as a Poisson process. With this model the statistics of A-weighted levels have been investigated for different situations with varying traffic flows. Results from an in-situ measurement have been compared with those from the numerical model, showing acceptable agreement. It is shown both by numerical modelling and measurements that the time variations in noise level are smaller in a courtyard than in a corresponding directly exposed situation. One of the additional conclusions is that the noise reduction of the maximum level can be significantly higher than that of the equivalent level.
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| 8. |
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| 9. |
- Forssén, Jens, 1968, et al.
(författare)
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Statistics of road traffic noise in shielded urban areas: an initial study of A-weighted levels
- 2006
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Ingår i: 6th European Conference on Noise Control: Advanced Solutions for Noise Control, EURONOISE 2006; Tampere; Finland; 30 May 2006 through 1 June 2006.
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Konferensbidrag (refereegranskat)abstract
- In the context of community noise and its negative effects, the noise descriptors used are usually long-term equivalent levels and, sometimes, maximum levels. An improved description could be achieved by including the time variations of the noise. Here, the time variations of A-weighted road traffic noise levels have been studied. Of special interest are situations with a shielded courtyard. For numerical results, a ray-tracing model has been used for calculating the sound propagation, and the traffic has been modelled as a Poisson process. A numerical study has been performed, where the statistics of A-weighted levels have been investigated for different situations with varying traffic flows. Also, results from an in-situ measurement have been compared with those from the numerical model, showing acceptable agreement. It is shown both by numerical modelling and measurements that the time variations in noise level are smaller in a courtyard than in a corresponding directly exposed situation. An additional conclusion is that the noise reduction of the maximum level can be significantly higher than that of the equivalent level.
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