| 1. |
- Desarnaulds, Victor, et al.
(författare)
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Swiss pendulous hammer for decoupling measurement of service equipment in wooden multi-storey building
- 2012
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Ingår i: EURONOISE 2012 - 9th European Conference on Noise Control. - 2226-5147. - 9788001050132 ; , s. 224-229
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Konferensbidrag (refereegranskat)abstract
- The latest Swiss standard SIA181 (6-2006 edition [1]) introduces a new methodology regarding the tests to be performed in new constructions for assessing noise induced by the manipulation of service equipment in bathrooms and kitchens. However, this method has been developed especially for massive constructions. In this study, we are investigating the relevance of such method for timber frame building, with typical structures including boxes, frames, massive floors, retrofitting solutions. Decoupling performances are particularly important in lightweight constructions, and the pendulous hammer method is actually aiming at evaluating the decoupling of service equipments. The goals for this work are to determine the advantages and the limitations of this method for theses specific cases. For example, airborne contribution can become critical and deserves a specific control. This project should also identify the main propagation paths for equipment noise. A series of in-situ measurements has been performed for various building constructions and service equipments. Some additional laboratories investigations have been conducted to optimize the decoupling of service equipments to fulfill the Swiss SIA standard requirements.
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| 2. |
- Hoever, Carsten, 1979, et al.
(författare)
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A Simulation-Based Parameter Study of Car Tyre Rolling Losses and Sound Generation
- 2012
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Ingår i: Proceedings - 9th European Conference on Noise Control, EURONOISE 2012, Prague, 10-13 June 2012. - 2226-5147. - 9788001050132 ; , s. 926-931
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Konferensbidrag (refereegranskat)abstract
- Due to legislative changes within the EU there is an increased demand for improvements in car tyre rolling resistance and noise generation. Apart from measurement data, however, information about the relationship between rolling resistance and rolling noise generation is scarce. It is the goal of this study to investigate the fundamental physical processes connecting both areas. Additionally, it is evaluated whether a simultaneous reduction of both rolling resistance and rolling noise is possible or if this is contradicting requirement. A previously presented model for simulating the structural dynamics and rolling resistance of a rolling car tyre is extended to allow rolling noise calculation. The approach is based on a waveguide finite element model of the tyre. Tyre/road contact forces are obtained using a non-linear 3D contact model. The velocity field on the tyre surface is used to determine the radiated sound pressure based on a boundary element method. In a parameter study it is evaluated how much dissipation and sound radiation are affected by material properties, tyre construction and road surfaces. Due to the characteristics of the modelling approach, detailed information about dissipation and sound generation in different frequency regions, wave orders or parts of the tyre is available. The results show that rolling resistance and radiation are mainly low wave order, low frequency phenomena which are, at least partly, controlled by the same set of modes. This suggests that by modifying specific tyre properties reductions in both sound radiation and rolling resistance can be achieved.
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| 3. |
- Hornikx, Maarten, 1980, et al.
(författare)
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The potential of vegetation for reducing road traffic noise at urban quiet sides
- 2012
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Ingår i: Proceedings - 9th European Conference on Noise Control, EURONOISE 2012, Prague, 10-13 June 2012. - 2226-5147. - 9788001050132 ; , s. 949-954
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Konferensbidrag (refereegranskat)abstract
- Reduction of noise from road traffic is one of the multiple benefits of employing vegetation in urban areas. In particular, application of vegetation to façades and roofs of residential buildings might be effective for increasing the quietness at the traffic-free side of these buildings, the quiet sides. The potential of reducing road traffic noise at the quiet side of buildings by a variety of vegetation-related measures is here studied by 2D and 3D full-wave numerical methodologies. The considered vegetation measures include wall vegetation systems, green roofs, vegetated low noise barriers at roof edges and combinations of such treatments. Green roofs appear to have the highest potential to enhance quietness at the traffic-free side of the buildings. For newly built roof systems, favourable combinations of roof shape and vegetation have been identified. Vegetated façades are efficient mostly when applied to narrow geometries with otherwise acoustically hard façade materials.
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| 4. |
- Hui, X, et al.
(författare)
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The outdoor soundscape design of Swedish hospitals
- 2012
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Ingår i: Ninth European Conference on Noise Control (Euronoise) 2012, 10-13 June, Prague, Czech Republic. - 2226-5147. - 9788001050132
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Konferensbidrag (refereegranskat)
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| 5. |
- van der Aa, Bart, 1985, et al.
(författare)
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Artificial refraction of sound propagating outdoors by a sonic crystal noise barrier with increasing cylinder diameter over height
- 2012
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Ingår i: Proceedings - 9th European Conference on Noise Control, EURONOISE 2012, Prague, 10-13 June 2012. - 2226-5147. - 9788001050132 ; , s. 938-943
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Konferensbidrag (refereegranskat)abstract
- Upward refraction of sound propagating outdoors by a finite set of two-dimensional cylinders has been studied in the homogenization region. All cylinders in the field are located above a ground plane and have their longitudinal axes orientated parallel to the ground. By increasing the cylinder radius with height, a medium is created which effective sound speed decreases over height. With a decreasing sound speed profile a cylindrical wave propagating inside such a structure can be refracted upwards, consequently creating a shadow zone behind the object. Acoustic phenomena for continuous graded index media (GRIN CM), predicted using the Finite Element Method (FEM), are demonstrated. Using modified homogenization formulas the results are then matched with a qualitatively equivalent graded index sonic crystal (GRIN SC), predicted with Multiple Scattering Theory (MST). In order to gain a reasonable insertion loss the barrier thickness must be chosen in accordance with the wavelength of the incoming field and should be in the order of a few wavelengths. Furthermore, it has been shown that the performance of these refractive structures is determined by the shape of the effective sound speed profile in relation to the point of excitation.
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| 6. |
- Van Renterghem, T., et al.
(författare)
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Road traffic noise reduction by vegetated low noise barriers in urban streets
- 2012
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Ingår i: Proceedings - 9th European Conference on Noise Control, EURONOISE 2012, Prague, 10-13 June 2012. - 2226-5147. - 9788001050132 ; , s. 944-948
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Konferensbidrag (refereegranskat)abstract
- Low-height noise barriers were shown to significantly reduce road traffic noise since these can be placed very close to either source or receiver. In this study, it is investigated to what extent such devices can be used in a street canyon setup. Full-wave numerical calculations have been carried out with the FDTD (finite-difference time-domain) method, the PSTD (pseudo-spectral time-domain) method and BEM (boundary element method). In addition, a combined ray model and radiosity (CRR) model has been used. Numerical results of the different wave-based methods have been cross-validated with satisfying agreement. The limitations of an energy-based method like CRR have been pointed out. 4-lane road traffic in a 19.2-m wide street canyon with a realistic façade profile has been considered. In the predictions, low screens are considered, covered by vegetated wall substrate. Different arrangements of such screens have been assessed, for receivers on walkways and distributed over the building facades. Road traffic noise could be reduced on walkways at low vehicle speeds, even when both sources and receivers are located in the same reverberant space. Some shielding for higher elevated receivers along facades is predicted as well. Absorption on the low-height noise barriers was shown to be essential to obtain positive effects.
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| 7. |
- Wei, W., et al.
(författare)
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An efficient model for background noise mapping
- 2012
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Ingår i: Proceedings - 9th European Conference on Noise Control, EURONOISE 2012, Prague, 10-13 June 2012. - 2226-5147. - 9788001050132 ; , s. 376-379
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Konferensbidrag (refereegranskat)abstract
- It has been shown that inhabitants of dwellings exposed to high noise levels benefit from having access to a quiet side. Therefore the European Environmental Noise Directive allows member states to include the presence of a quiet side in their reports. However, current practice applications of noise mapping methods usually underestimate the noise level at the shielded façade when the most important contribution is sound propagation over the rooftop. Multiple reflections from opposite façades in street canyons are not sufficiently taken into account. In addition, sources at distance much larger than normally taken into account in noise maps might in some cases still contribute significantly. Since one of the main reasons for this poor approximation is computational burden, an efficient engineering model is proposed, which considers multiple reflections and turbulence scattering. The model uses an analytical function of a complexity comparable to ISO 9613 formula for noise barriers that is fitted to an extensive set of FDTD (finite difference time domain) simulations of canyon-to-canyon sound propagation. This model allows calculating the background noise in the shielded areas of a city, which could then be used to refine noise mapping calculations.
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| 8. |
- Beckenbauer, Thomas, et al.
(författare)
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Tyre/road noise prediction: A comparison between the SPERoN and HyRoNE models, Part 1
- 2008
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Ingår i: 7th European Conference on Noise Control 2008, EURONOISE 2008; Paris; France; 29 June 2008 through 4 July 2008. - 2226-5147. ; , s. 2933-2938
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Konferensbidrag (refereegranskat)abstract
- The SPERoN and HyRoNE models predict the pass-by tyre/road noise of a passenger car from intrinsic characteristics of the road surface. Both models are hybrid: they combine statistical laws with physical models. With a computing time of a few minutes (very quick compared to full physical models), they provide operational tools for tyre/road noise prediction. Particular fields of interest are road surface optimisation with respect to noise at the laboratory scale, conformity of production of a new surface and acoustic monitoring of roads. They are now implemented as user-friendly stand-alone applications. The presentation will address the principles of the models, their performances and their respective main fields of application. Part 1 will address the philosophy and the principles of the models.
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| 9. |
- Bergman, Penny, 1982, et al.
(författare)
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Emotion and meaning in interpretation of sound sources
- 2008
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Ingår i: 7th European Conference on Noise Control 2008, EURONOISE 2008, Paris, France, 29 June - 4 July 2008. - 2226-5147. ; , s. 3925-3929
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Konferensbidrag (refereegranskat)abstract
- Research regarding the perception of sound focuses in large on the acoustical properties of the sound. We argue that, for a more complete picture of sound perception, one must take the non-physical properties into account. By changing the emotional descriptor of a sound the perception in terms of level of annoyance will change. The present study investigates how a priming picture placing the origin of the sound to either a positive or negative environment affects the level of annoyance to same sound. 3 different sounds were used in the experiment, all based on pink noise. The participants were in the beginning of each sound exposed to a picture telling where the sound originated. The picture was either a positive environment (a picture of a waterfall) or a negative environment (a picture of a larger factory). While listening to the sounds the participants completed different performance tasks. In the end of each sound the participants rated level of annoyance to the sound. Results show that the annoyance ratings are significantly lower when primed with a positive picture. Results also indicate that for more attention demanding tasks this correlation is stronger. The findings are discussed in relation to theories of sound perception.
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| 10. |
- Bolmsvik, Åsa, 1975-, et al.
(författare)
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FE modeling of a lightweight structure with different junctions
- 2012
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Ingår i: Proceedings of EURONOISE 2012. - : European Acoustics Association. - 9788001050132 ; , s. 162-167
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Konferensbidrag (refereegranskat)abstract
- In lightweight structures it is common to use damping material in junctions to decrease sound transmission. In field measurements, the damping properties of the structure are easily overestimated due to the omnipresent energy losses to the surroundings. Thus, reliable estimates of structural properties cannot be guaranteed. Vibrational tests were done on a full scale wooden construction, consisting of a floor and supporting beams, representing walls, to investigate the effect of different junctions. Totally seven different setups were made using the same building components. In one setup the floor and the walls were screwed together, in five setups different elastomers was positioned between the floor and the walls and in the last setup the floor was resting free on top of the walls. A shaker, with pseudorandom excitation, was used for the excitation of the structure and accelerometers were used for response measurements. The effect of the junction was investigated by studying the acceleration levels in the edge part of the floor-wall junction in different directions. Modal data, extracted from test data using experimental modal analysis, form input and validation data for the following finite element (FE) analysis. Two FE models; modeling one elastomer and the screwed setup, are used for the studies. The aim was to study if the eigenmodes rendering the acceleration levels are similar in test and in analysis, using common material properties. The results from correlation between test and analytical results show that the material properties of the wood need to be known better; more sophisticated models are needed to fully simulate the dynamic behavior of the structure. Anyhow, with the used properties the mode shapes are captured fairly well in the lower frequencies. Furthermore, the experiment shows that the damping properties of the junction material have a major influence on the behavior of the structure.
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