| 1. |
- Bard, Delphine, et al.
(författare)
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In situ and laboratory measurement of service equipment decoupling in lightweight constructions
- 2013
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Ingår i: 42nd International Congress and Exposition on Noise Control Engineering 2013 (INTER-NOISE 2013) : Noise Control for Quality of Life - Noise Control for Quality of Life. - 9781632662675 ; 3, s. 1801-1809
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Konferensbidrag (refereegranskat)abstract
- The latest version of the Swiss standard for building acoustics (SIA181) introduced a new measurement method, based on a balanced- Arm hammer, for evaluating the decoupling performance of service equipment. This method was developed for reproducing in a standard manner the manipulation of service equipment in bathrooms and kitchens. In this study, we are investigating the relevance of such method for timber frame building where decoupling performances are particularly important. This study determines the advantages and the limitations of this methodology, which allows identifying the main propagation paths for equipment noise. A series of in-situ measurements has been performed to identify the best building constructions, service equipment configurations but also some workmanship errors. Laboratories investigations have also been conducted to understand and optimize the decoupling of two type service equipment systems.
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| 2. |
- Forssén, Jens, 1968, et al.
(författare)
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Initial results for traffic noise mitigation with Helmholtz resonators in the ground surface beside a road
- 2013
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Ingår i: 42nd International Congress and Exposition on Noise Control Engineering 2013: Noise Control for Quality of Life, INTER-NOISE 2013; Innsbruck; Austria; 15 September 2013 through 18 September 2013. - 9781632662675 ; 3, s. 2345-2352
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Konferensbidrag (refereegranskat)abstract
- For reduction of road traffic noise, measures focussing on the propagation path are needed as complements to measures at source. Here, the effect of Helmholtz resonators, buried in the ground surface alongside the road, is investigated. Possible benefits of buried resonators are that they can function without obstructing the accessibility to the protected area. A modelling approach using equivalent sources is described for a coupled field of resonators in an otherwise acoustically hard ground plane. The model is validated in comparison with laboratory measurements. For selected road traffic cases, the model is used to predict the effect of resonators in a grid pattern within a strip along the road, showing noise reductions of 2-4 dBA.
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| 3. |
- Glav, Ragnar, et al.
(författare)
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Analysis of a cylindrical micro-perforated resistive silencer
- 2013
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Ingår i: 42nd International Congress and Exposition on Noise Control Engineering 2013, INTER-NOISE 2013. - : OAL-Osterreichischer Arbeitsring fur Larmbekampfung. - 9781632662675 ; , s. 5867-5876
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Konferensbidrag (refereegranskat)abstract
- This paper presents an analytical wave decomposition model for predicting the transmission loss a cylindrical silencer with both annular and baffled micro-perforated screens. Numerical simulation shows the fundamental characteristics as well as the potential to achieve large attenuation using micro-perforations. The numerical model is verified by measurements using the 2-microphone technique and shown to be a useful tool in practical design. Clear from the analysis is the sensitivity of the micro-perforated silencer to changes in both porosity and overall layout.
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| 4. |
- Griefahn, B., et al.
(författare)
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Moderators that influence annoyance of residents near 6 European airports
- 2013
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Ingår i: 42nd International Congress and Exposition on Noise Control Engineering 2013, INTER-NOISE 2013. - : OAL-Osterreichischer Arbeitsring fur Larmbekampfung. - 9781632662675 ; , s. 1072-1080
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Konferensbidrag (refereegranskat)abstract
- The aim of the present study was to identify possible moderator variables that influence annoyance due to aircraft noise. The data analysed here were ascertained by extended questionnaires in three studies within the COSMA-Project that was funded by the European Union. There were a Field Study and a Telephone Interview, each performed with residents living in the vicinity of the airports Cologne-Bonn, London Heathrow or Stockholm- Arlanda and a Laboratory Study performed with residents living near the airports Budapest, Lyon or Paris. In each of the three studies (and the overall 9 subgroups) the participants completed extended questionnaires on long- Term annoyance. In the field study sleep behaviour and acute annoyance that was rated each hour were additionally ascertained over a period of 4 days. Using a logistic regression model analysis odds ratios were determined for possible moderators. Based on the results a model was created that shows the most important negative and positive influences.
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| 5. |
- Kogan, Pablo, et al.
(författare)
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Early identification of urban locations towards soundscape analysis
- 2013
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Ingår i: 42nd International Congress and Exposition on Noise Control Engineering 2013, INTER-NOISE 2013 : Noise Control for Quality of Life - Noise Control for Quality of Life. - 9781632662675 ; 7, s. 5537-5545
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Konferensbidrag (refereegranskat)abstract
- Soundscape management in a city implies mitigating harmful sounds and promoting useful ones, according to their environmental, social or cultural significance and considering a more human centered paradigm. The Soundscape approach does not consider sound as a waste but a resource and its application may reach more benefits than solely noise control actions. This conception conveys an emerging paradigm, which requires novel and cross-disciplinary methodologies for its application. In this direction, every location in a city has its own dynamics and this should be weighed. Thus, preliminary area exploration represents a strategic action allowing one to identify key soundscape spots, optimize the data acquisition, and adjustment of methodologies. This work presents the conceptual foundations, empirical methods and some preliminary results for the early identification of urban study sites.
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| 6. |
- Kårekull, Oscar, 1979-, et al.
(författare)
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Comparison of RANS parameters for flow noise prediction
- 2013
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Ingår i: 42nd International Congress and Exposition on Noise Control Engineering 2013, INTER-NOISE 2013. - : OAL-Osterreichischer Arbeitsring fur Larmbekampfung. - 9781632662675 ; , s. 5916-5925
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Konferensbidrag (refereegranskat)abstract
- TThe use of Computational Fluid Dynamics (CFD) and especially Reynolds Averaged Navier Stokes Equations (RANS) simulations is a well-established tool in industry for performance evaluation of constrictions in low speed flow ducts. However, the use of CFD simulations for noise predictions is not as common. In this paper, two different models to predict the sound spectra through the use of RANS simulations and a noise reference spectrum are compared and evaluated. One method predicts the sound based on the pressure drop whereas the other method is based on the turbulent kinetic energy. The influence of both turbulence models as well as mesh properties have been investigated. Noise predictions from simulation results are compared to noise measurement results of an orifice in a duct. The comparison between the simulated results and measured data are in excellent agreement. The benefit of using the pressure drop, as input data, is a lower sensitivity to both the structure and the resolution of the mesh. Also, this model has a more general definition allowing a consistent method for different constriction geometries. Still, predictions using the turbulent kinetic energy result in equivalent accuracy and even if the choice of input data is more complex it can be preferred in special cases.
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| 7. |
- Lennström, David, et al.
(författare)
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Prominence of tones in electric vehicle interior noise
- 2013
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Ingår i: Internoise 2013. - Innsbruck : ÖAL Österreichischer Arbeitsring für Lärmbekämpfung. - 9781632662675 ; , s. 508-515
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Konferensbidrag (refereegranskat)abstract
- The rapid increase of various types of electric vehicles introduced creates new challenges also in respect to noise control and sound quality. With the absence of acoustic emissions from an operating internal combustion engine, the presence of high pitched tonal components from the electric traction motor can be pronounced in many driving conditions. In order to fulfill the customer’s expectations of interior acoustic comfort, further knowledge needs to be gained about the perception of tonal components appearing in a mix of random noise from wind and tires. This paper presents a study on the relationship between the psychoacoustic metric prominence ratio (PR) and the threshold of detecting the tones and also the perceived annoyance for both constant speed and acceleration in a pure electric vehicle. The listening test results reveal that below 800 Hz, a higher PR value is required for audibility compared to tones above 2.5 kHz. For all driving conditions, the perceived annoyance was relatively low with small differences between the frequency ranges for the low audibility stimuli (PR≤2 dB). With higher audibility (PR≥3 dB), the perceived annoyance was significantly increased for frequencies above 5 kHz compared to frequencies below 800 Hz for the constant speed cases. The acceleration cases yielded similar conclusions. The findings are intended to support in the requirement specification process for sounds in electric vehicles.
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| 8. |
- Ljunggren, Fredrik, et al.
(författare)
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Findings from the AkuLite project : Correlation between measured vibro-acoustic parameters and subjective perception in lightweight buildings
- 2013
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Ingår i: Internoise 2013. - Innsbruck. - 9781632662675 ; , s. 1578-1585
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Konferensbidrag (refereegranskat)abstract
- Various research aspects on sound and vibrations in lightweight buildings are covered by the Swedish research programme AkuLite. One of the most important topics has been to find out to what extent objective measured parameters correlate with subjective opinions from people living in multifamily houses. Typical questions to be pointed out are: Do existing ratings like R'w (+C50-1350) and L'n,w (+CI,50-2500) correlate well enough to the tenants' perception? Can other measureable parameters be found that show better agreement? Are the often used frequency limits of 100Hz or 50Hz low enough? Can any significant differences be seen when comparing lightweight buildings with concrete buildings? Extensive sound and vibration measurements have been performed in numerous buildings of varying construction including lightweight timber or steel based framing, cross laminated timber and concrete. In general frequencies from 20 Hz have been covered. Questionnaires have been distributed to the tenants where they were asked to give their opinion on a number of adequate questions related to sound and/or vibration perception. The results from the measurements and from the questionnaires have then been compiled, followed by a comprehensive statistical analysis in order to see the degree of correlation between them.
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| 9. |
- Lundberg, Oskar, 1980-, et al.
(författare)
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Non-linear contact forces for beam/ball-interaction and its influence on the dynamic response of the beam
- 2013
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Ingår i: 42nd International Congress and Exposition on Noise Control Engineering 2013, INTER-NOISE 2013. - : OAL-Osterreichischer Arbeitsring fur Larmbekampfung. - 9781632662675 ; , s. 238-247
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Konferensbidrag (refereegranskat)abstract
- A well-defined rolling contact problem is studied with the intention to cover interesting aspects of tyre-road contact modeling and rolling contact in general. More specifically, the dynamic response in a steel beam caused by a steel ball rolling over it is studied by theoretical modeling of the beam- And ball dynamics as well as the contact forces. Validation of the dynamic response simulations is achieved by comparison with measurements. The contact model is shown to be greatly dependent on an accurate estimate of the real contact stiffness. A method to estimate the contact stiffness which leads to good accuracy in dynamic response simulations is presented. Although the contact stiffness is significantly lower for rubber- Asphalt interaction than for steel-steel contact, the results give useful insight for tyre-road contact modeling.
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| 10. |
- Mehrgou, Mehdi, et al.
(författare)
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On sound power measurement of the engine in anechoic room with imperfections
- 2013
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Ingår i: 42nd International Congress and Exposition on Noise Control Engineering 2013, INTER-NOISE 2013. - : OAL-Osterreichischer Arbeitsring fur Larmbekampfung. - 9781632662675 ; , s. 4358-4364
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Konferensbidrag (refereegranskat)abstract
- Engine noise is one of the most critical noises in urban noises. NVH improvements are essential in order to fulfill various noise emission regulations such as ISO 362. Reducing engine noise has become a necessity for engine developers. Measurement plays an important role beside the simulations to improve the NVH behavior, because the engine is a rather complicated mechanical system with many components. ISO 3745 is an ideal method for sound power measurement for internal combustion engines since it provides a fast measurement through many different engine speeds. However room as well as the measurement method, should comply with this standard. Because of the size and installation situation for a running engine there is limited space for measurement; and it is difficult to reach standards requirements especially for such a directive sound source. The difficulty to meet these requirements also applies to Scania's anechoic room. Here engine noise characteristics and the uncertainties in sound power measurement have been discussed based on both measurement and simulation. Recommendation has been made to decrease the uncertainty of sound power measurement.
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