| 1. |
- Algers, Staffan, et al.
(författare)
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Embedded parks in Quiet Zones
- 2012
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Ingår i: 41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012. - 9781627485609 ; , s. 3024-3035
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Konferensbidrag (refereegranskat)abstract
- One of the targets of the European project "CityHush Acoustically Green Road Vehicles and City Areas" under the 7th Framework Program is to support city administrations to eliminate harmful effects of noise exposure and decrease levels of transport noise, especially in urban areas. A particular attention has been paid to investigating boundary conditions and maximum noise gains especially for parks embedded in Q-zones where only quiet low emission vehicles are tolerated. Other vehicles are banned or subject to a noise fee for entering the quiet zone. Within the CityHush project existing noise levels in different parks of European cities were determined and the influence of local parameters on the noise situation, such as size of a Qzone, was investigated. Moreover a variation of noise fees and traffic restrictions as well as different percentages of low noise vehicle ownerships inside the Q-zone and outside (countrywide) was evaluated. Based on different noise and annoyance criteria possibilities and limits to reduce noise in the city environment will be shown, based on studies carried out for 5 European cities.
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| 2. |
- Allam, S., et al.
(författare)
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Cooling fan noise control using micro-perforates
- 2012
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Ingår i: Int. Congr. Expos. Noise Control Eng., INTER-NOISE. - 9781627485609 ; , s. 10434-10445
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Konferensbidrag (refereegranskat)abstract
- Baffle or split silencers are commonly used, e.g., in HVAC systems and as inlet/outlet silencers on gas turbines. Another application is to reduce noise from the cooling fan inlet for large IC-engines. A baffle silencer can be seen as a periodic arrangement of parallel rectangular absorbers which can be placed in a rectangular duct. The noise reduction afforded by parallel baffles depends not only on the physical properties of the lining, but also upon the angle of incidence of the sound waves impinging and the baffle length. In this paper the potential of using baffles made of Micro-Perforated Panels is investigated in particular with the cooling fan inlet application in mind. Theoretical models for the damping is derived and used to design optimum configurations. The models are based on the wave propagation in a periodic array of baffles so that only one period can be investigated in order to find the different modes. In particular the least attenuated mode is important to find in order to optimize the behavior. An important aspect is the inner structure of the MPP baffle, i.e., can it just be an empty air volume or to what extent must internal waves be prevented by putting in walls. From a stiffness point of view some inner walls might also be needed to avoid vibration problems. Due to these complexities the theoretical models are only presented for the simplest cases. In order to validate the models and to get a more complete test of different designs experiments were also carried out. During these experiments the effect of flow was also tested.
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| 3. |
- Bard, Delphine, et al.
(författare)
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Swiss pendling hammer for decoupling measurement of Swiss methodology for decoupling measurement of service equipment in buildings
- 2012
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Ingår i: 41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012. - 9781627485609 ; 12, s. 10293-10301
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Konferensbidrag (refereegranskat)abstract
- The latest edition of the Swiss standard SIA181(2006) Protection against noise in Buildings [1], introduces a new methodology regarding the tests to be performed in new constructions for noise induced by human using service equipment in bathroom and kitchen. In this method, a specific pendling hammer has been developed especially for evaluating the decoupling efficiency of service equipment. The goals for this work are to determine the advantages and the limitations of method especially for lightweight constructions. For example, in some cases the airborne contribution of the pendling hammer noise can become critical and leads to an overestimation of the uncoupling. This project should also identify the main propagation paths for equipment noise. A large number of in-situ measurements have been done for various building constructions and services equipment in Swiss and Swedish constructions. Some additional laboratories investigations have been conducted to optimize the decoupling of service equipment to fulfill the Swiss requirements.
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| 4. |
- Billström, Niklas, et al.
(författare)
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Can we improve acoustic environments by adding sound
- 2012
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Ingår i: Proceedings of the 41st International Congress and Exposition on Noise Control Engineering. - 9781627485609
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Sound is central to the identity of a place, but is nonetheless a frequently neglected component in the design process. We believe that urban soundscape planning and product sound design has much to gain by collaborating with the artistic and humanistic fields of knowledge. Applying acoustics and perception psychology as well, the sound laboratory at Konstfack University College of Arts, Crafts and Design examined the domain of acoustic design in the research project ISHT – The Interior Sound Design of High-Speed Trains – in collaboration with, among others, train manufacturer Bombardier. Empirical data in this study is focused on train travel, but can easily be transposed to other contexts, such as public spaces. Methods for improving sonic experience in relation to criteria such as identity and specific needs were explored. Our thesis question was: How to create a comfortable and appealing environment by adding sounds (distributed via speakers)? The interdisciplinary research methods included field observations, listening tests, and quantitative data, as well as public exhibitions and collaborations with composers.
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| 5. |
- Buckers, C., et al.
(författare)
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Analysis of the acoustic characteristics and optimization potential of road surfaces - One focus within the project "Quiet Road Traffic 3"
- 2012
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Ingår i: 41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012; New York, NY; United States; 19 August 2012 through 22 August 2012. - 9781627485609 ; 6
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Konferensbidrag (refereegranskat)abstract
- The development of silent road surfaces demands a detailed analysis of the tire/road interaction mechanisms basically determining the noise radiation of flowing traffic. Such an analysis is of significant importance to identify and characterize the relevant effects which affect the acoustic properties of the pavements. This paper reviews the approaches pursued within the interdisciplinary research project "Quiet Road Traffic 3" including an adequate expansion of the SPERoN model for the quantitative prediction of the tire/road noise. A variety of novel materials and road constructions is investigated to validate the model, to design optimized pavements, and to explore their application potential. The practical use of the results will be finally checked by implementing and monitoring test tracks. The research activities cover asphalt as well as concrete construction techniques and focus in particular on measures to reduce the noise nuisance in agglomerations. In total, the approaches within the project "Quiet Road Traffic 3" are intended to lower the road traffic noise level by 4 to 6 dB(A) as compared to the current state of the art.
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| 6. |
- Elnady, T., et al.
(författare)
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Estimation of temperature drop in exhaust systems
- 2012
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Ingår i: 41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012. - 9781627485609 ; , s. 9362-9375
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Konferensbidrag (refereegranskat)abstract
- The analysis of the acoustic performance of exhaust systems is affected by the flow speed and temperature of the exhaust gases. The flow speed affects the convective wave speed and changes the acoustic properties of some acoustic elements such as perforates. The temperature of the exhaust gas affects its density and the speed of sound. It is important to model the flow and temperature distribution within the exhaust system in order to perform an accurate acoustic simulation. The acoustic propagation along an exhaust system can be modeled by dividing the exhaust system into a number of two-port elements. It has been previously shown that flow distribution and pressure drop calculation can be done using the same two-port elements but using a different set of transfer matrices. In this paper, we are proposing a new method to calculate the temperature drop using the same two-port elements but using another set of transfer matrices. This technique has the advantage to solve all physics by defining only one network. The heat is dissipated through the pipe wall via convection, conduction, and radiation. Several cases were designed to validate the new technique. They show that it works as expected.
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| 7. |
- Färm, Anna, 1984-, et al.
(författare)
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On variation of absorption factor due to measurement method and correction factors for conversion between methods
- 2012
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Ingår i: 41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012, Volume 11, 2012. - : Institute of noise control engineering. - 9781627485609 ; , s. 9343-9350
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Sound absorbing materials are used in many applications to reduce sound, and their soundabsorbing characteristics are most often determined experimentally since theoreticaldetermination is difficult. Sound absorption factors are used in material specifications aswell as input to numerical simulations.Several methods for experimental determination of the absorption factor exist, two of themstandardized and frequently used. It is commonly known that the absorption factorobtained by these two methods differs as different sound fields are prescribed by thestandards. However, the size of the differences has not been so well described. Due to thisdifference, the choice of method is critical in order to avoid errors in simulations andspecifications of material properties.Experimental determination of absorption factors for three commonly used absorbers wasperformed, resulting in significant differences between the two methods. Correction factorsto compensate the absorption factor determined at one acoustic state and used in anotherare given. Theory verifying the differences is also presented.
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| 8. |
- Hagberg, Klas, et al.
(författare)
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Design principles of small multi storey wooden houses
- 2012
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Ingår i: 41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012. ; 3, s. 2327-2333
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Konferensbidrag (refereegranskat)abstract
- Many multifamily houses are produced by small or medium size enterprises (SME's). These developers produce a substantial number of residential units per year. They have normally limited resources and need to have easy access to cost - effective structural solutions. Typical buildings comprise two storeys and four to eight flats. Due to costs and production efficiency these buildings are produced in light material, mainly wood. Each building is unique and the limited size of each project means that it cannot defray costs to adapt each building of interest, to available building system on the market. Instead, the builders need to have access to; 1. structural design guidelines to secure dimensions and acoustic performance; 2. assembly information regarding details; 3. process guidance to minimize risk exposure, secure the final result. This paper describes a typical design procedure and final results, for a small two - storey building comprising six residential units. The procedure fits to an SME, with limited resources for technical development. The building was designed and erected presupposing that everything has to be built "on site". This paper is also an introduction to a new guidance book, being prepared within the Swedish research project AkuLite.
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| 9. |
- Hornikx, Maarten, 1980, et al.
(författare)
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On the improved point-to-point calculations for noise mapping in shielded urban areas
- 2012
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Ingår i: 41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012; New York, NY; United States; 19 August 2012 through 22 August 2012. - 9781627485609 ; 6, s. 5223-5234
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Konferensbidrag (refereegranskat)abstract
- Noise mapping of urban areas according to standardized engineering calculation methods systematically results in an underestimation of noise levels at areas shielded from direct exposure to noise, such as inner yards. In these methods, road traffic lanes are represented by point sources and noise levels are computed utilizing point-to-point propagation paths. For a better prediction of noise levels in shielded urban areas, the attenuation terms describing these propagation paths are extended by terms including geometrical aspects of the urban environment both in the source and in the receiver area. In the present work, it has been studied to what extent these terms may be treated as being independent of the source-receiver distance. Also, the validity of treating the propagation path in a 2D plane rather than in 3D is investigated. Results obtained from a wave-based acoustic propagation model have been used for this assessment.
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| 10. |
- Hynninen, A., et al.
(författare)
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Procedure to estimate the in-duct sound power in the high frequency range with non-plane waves
- 2012
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Ingår i: ASME 2012 Noise Control and Acoustics Division Conference at InterNoise 2012. - : ASME Press. - 9780791845325 ; , s. 181-191, s. 8026-8036
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Konferensbidrag (refereegranskat)abstract
- The acoustic characterization of fluid machines, e.g., internal combustion engines, compressors, or fans is of great importance when designing the connected duct systems and its silencers. For machines connected to large ducts where also the non-plane wave range is important, for instance large diesels and gas turbines, a suitable way to characterize the source is to determine the sound power under reflection free conditions. For the low frequency plane wave range in-duct sound power can be measured with the widely used two microphone method. The goal of this study is to investigate how, starting from the two-microphone approach, a suitable wall mounted microphone configuration can be defined and used to estimate the propagating in-duct sound power also beyond the plane wave range. For this purpose an acoustic source test-rig was built and numerical simulations were also conducted. The in-duct sound power from monopole, dipole, and quadrupole source types was determined using twelve wall mounted microphones and cross-spectra averaging methods. The in-duct results were compared against sound power measured using the reverberation room method (ISO 3741). Based on the simulations and the experimental results the best microphone positions and weighting factors were determined.
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| 11. |
- Hällgren, Nina, 1977-
(författare)
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Qualitative sound analysis - A tool for understanding and communicating urban acoustic space
- 2012
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Ingår i: 41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012. - 9781627485609 ; , s. 2167-2172
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Konferensbidrag (refereegranskat)abstract
- Today over 50% of the world's inhabitants live in cities and the urbanization continues to increase. Cities tend to be more condensed than before while they also cover larger and larger areas of land. Demands for infrastructural ameliorations and extensions are natural consequences of this development. Other factors that hold a strong presence in urban public space are the distribution of goods, services and commercial advertisements. These components, including man himself not least, are all active in the creation and dissemination of sound. Together they interact with the built environment and generate the conditions for our experience of the city and its various acoustic spaces. An important challenge is to enhance the consciousness concerning urban acoustic quality and to spread that knowledge to those responsible for shaping and reshaping our public spaces, such as architects and urban planners. How can we broaden the discussion about urban soundscapes and create a basis for creative design strategies in the future? One possible way to go is through the development of analogue and digital tools that may imply increased understanding and new insights concerning the relation between built structure, sonic emission and lived experience.
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| 12. |
- Kihlman, Tor, 1934
(författare)
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Noise policy - integration with climate and natural resource policies
- 2012
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Ingår i: Proceedings Inter-Noise 2012, 41st International Congress on Noise Control Engineering, New York, August 2012.. - 9781627485609 ; 1
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Konferensbidrag (refereegranskat)abstract
- Climate change policy is difficult. Noise policy is even more difficult because of its complexity. There is such a wide range of society’s processes/activities in which noise problems are integrated. There are win/win situations. Lower noise emissions facilitate healthy quiet compact cities. Compact cities save land use and fuel, have typical shorter travelling distances, lower speeds are possible. Barrier effects can be reduced. Walking and bicycling can be promoted. There are conflicts. Demands upon reduced fuel consumption and cleaner exhaust gases from road vehicles and jet engines make the noise emission problems tougher. Traffic safety demands on roads may collide with ways to reduce the noise emissions. Politicians in national and international bodies call noise a local problem which, however, local politicians cannot solve if not the source levels get reduced which is an area for international agreements. National industrial interests delay progress towards quieter products. Economic sub-optimization lead to unfortunate end results. To get a really quieter world demands that planners, builders, industries, etc. all do more. Speed policy is an important area. Few politicians understand the real complexity of the noise problems. We, noise professionals, have to spend more time on teaching and influencing them.
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| 13. |
- Knutsson, Magnus, et al.
(författare)
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Low frequency damping from turbulence with application to charge air coolers
- 2012
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Ingår i: Int. Congr. Expos. Noise Control Eng., INTER-NOISE. - 9781627485609 ; , s. 9424-9433
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Konferensbidrag (refereegranskat)abstract
- As a consequence of its contribution to the global warming the necessity of reducing the CO2 emissions from transportation is dramatically increasing. One effective measure to meet this requirement with respect to the passenger car segment is to conduct IC-engine downsizing. To meet requirements for high power and torque output turbo- or supercharging in combination with charge air cooling is regularly used. Both compressors and charge air coolers will largely influence the sound transmission though the air intake system. In order to make a proper system optimization where pressure drop, heat exchange efficiency and acoustics are balanced within a given space accurate models are required. Inside most charge air coolers the cooling takes place in parallel narrow channels where boundary layers dominate the behavior. This paper presents a new acoustic model for charge air coolers where low frequency damping from interaction between acoustic boundary layers and turbulence is important. The predictions are compared with experimental data taken at room temperature and show good agreement. More than 5 dB transmission loss is demonstrated at low frequencies that can be used for noise control.
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| 14. |
- Larsson, Krister, et al.
(författare)
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Influence of tapping machine position on timber joist floors on the low frequency impact sound
- 2012
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Ingår i: 41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012. - 9781627485609 ; , s. 6620-6630
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Konferensbidrag (refereegranskat)abstract
- ISO plans to replace the current ISO 140-7 standard for the measurement of impact sound pressure level by a new standard, ISO 16283-2. Within the standardization work, we have examined the influence of the position of the tapping machine (TM) on top of a timber joist floor (built as the reference light weight floor 2 in ISO 10140 and the previous ISO 140-11). The question is whether it is sufficient to prescribe that the TM positions shall be randomly distributed over the floor area (as in ISO 140-7) or if they should be specified to hit the joists with one hammer (as in ISO 10140) or even hit the joists with all hammers. The room average sound pressure level was measured with 63 evenly distributed TM positions on the floor, either on top of a joist or on the web. The influence of the TM position relative the joists is rather stable at low frequencies (25-160 Hz). Having the TM at right angles to the joists and one hammer striking a joist, the average difference is 3 dB to when no joist is being hit. Comparing positions where all hammers hit the joists with positions in between the joists, the difference is typically 4-7 dB in the frequency range 25-160 Hz. The results indicate that the ISO 16283-2 could prescribe more precisely where the TM shall be positioned in order to reduce the random variations. One choice is then to follow ISO 10140-1, where the TM is placed at 45 degrees centered on the joists, such that one hammer strikes a joist.
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| 15. |
- Lindebrink, Josefin, et al.
(författare)
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An interactive auralization method using real-time sound sources
- 2012
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Ingår i: Proceedings of the 41st International Congress and Exposition on Noise Control Engineering (InterNoise 2012), 19-22 August 2012, New York City, NY, USA. - 9781627485609 ; 7, s. 6091-6102
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Konferensbidrag (refereegranskat)abstract
- During recent years, auralization methods have evolved towards using more interactive measures. The use of interactive elements, like navigation in static sound fields, has proven to be very significant in order to better integrate the listener with the simulated soundscape. In this study the possibility of engaging the user by actively contributing to the sound field is explored. Enabling the subject to act as a sound source and allowing communication within the environment, utilizing real-time synthesis of an acoustic environment's response. Auralization allows for a psychoacoustic evaluation of the acoustical space and therefore plays an important part in a wider understanding of different environmental characteristics. With an auralization framework adapting this kind of interaction, experience of the acoustical response is enabled and can thus be used as a tool in the process of subjectively assessing the acoustical space. Real-time convolution software implementing this mode of procedure has been designed. A subjective evaluation has been performed using a listening room equipped with an ambisonics multi-channel reproduction system, and a directional microphone with feedback control. Evaluation results indicate a positive response from the subjects to the added control over the simulated space.
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| 16. |
- Ljunggren, Fredrik, et al.
(författare)
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How to match building acoustic measurements with subjective judgments
- 2012
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Ingår i: Inter-Noise 2012. - 9781627485609 ; , s. 8922-8996
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Swedish research program AkuLite deals with various aspects regarding sound and vibration within lightweight buildings. As the popularity of lightweight block of flats increases it has been noticed that standardised (ISO) measurements, like airborne and impact sound insulation, tend to show different correlation with subjective experiences compared with concrete buildings. It is therefore of importance to either develop existing evaluation methods or to find new measurement parameters for better correspondence. In the project, series of sound and vibration measurements are carried out in various types of buildings. The measurements include extended frequency range and various sources as well as increased number of extracted parameters compared to existing standards. In parallel, questionnaires are distributed to the tenants, in the same buildings, where they give answer to questions regarding the experienced sound annoyance in their flat. Statistical analysis of the correlation between the objective measurement parameters and the subjective opinions from the tenants will be carried out.
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| 17. |
- O'Reilly, Ciarán J.
(författare)
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Acoustic propagation in a lined duct using a wave expansion method
- 2012
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Ingår i: 41st International Congress and Exposition on Noise Control Engineering, INTER-NOISE. - : Institute of Noise Control Engineering (INCE). - 9781627485609 ; , s. 6577-6587
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Acoustic liners are used extensively in engineering applications, particularly in aero-engines. Liners are characterised by a complex impedance, which is dependent on the grazing flow velocity and acoustic pressure spectrum at the liner surface. The acoustic propagation through a lined duct is examined in this paper using a wave expansion method. This is a highly efficient full domain discretisation method, based on interpolation of plane wave functions, which is suitable for solving a convected Helmholtz equation. For a potential flow, the boundary layer and the lined wall are included in the numerical scheme by the Myers boundary condition. This assumes that the acoustic pressure and particle velocity are continuous across a thin boundary layer. The acoustic propagation through a flow-impedance tube is computed in order to validate the implementation of the impedance boundary condition in this scheme. Good agreement with the experimental data from the literature is shown.
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| 18. |
- Rönnberg, Jerker, et al.
(författare)
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Speech understanding in noise: the role of working memory capacity
- 2012
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Ingår i: 41st International Congress and Exposition on Noise Control Engineering 2012 (INTER-NOISE 2012). - : Institute of Noise Control Engineering. - 9781627485609 ; , s. 508-516
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 19. |
- van der Aa, Bart, 1985, et al.
(författare)
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Numerical comparison of traditional noise screens and refractive graded index sonic crystal noise barriers in downwind sound propagation
- 2012
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Ingår i: Proceedings of the 41st International Congress and Exposition on Noise Control Engineering (InterNoise 2012), 19-22 August 2012, New York City, NY, USA. - 9781627485609 ; 9, s. 7183-7189
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Konferensbidrag (refereegranskat)abstract
- Sound propagation over a traditional noise screen in downwind conditions is numerically investigated and compared with a graded index sonic crystal (GRIN SC) noise barrier. The latter type of noise barrier creates a shadow zone by upward refraction of waves propagating through. Upward refraction is here achieved by varying the cylinder radius with height hence creating a graded index medium which effective sound speed varies accordingly. Contrary to GRIN SC noise barriers, traditional noise screens aim at improving the sound environment by screening sound emanating from, e.g. traffic noise sources. It has been shown that in downwind propagating conditions traditional solid screens introduce large wind speed gradients above the barrier top, which may give rise to downward refraction of acoustic waves into the shadow zone. In two-dimensional space, wind speed profiles of a traditional screen and an acoustically equivalent GRIN SC noise barrier are numerically computed using computational fluid dynamics. The modeled background flow, treated as an effective sound speed, is then used as input parameter for acoustic propagation calculations. The acoustic performance of both structures including a non-uniform background flow has been evaluated for a simple outdoor setup assuming a hard reflecting ground surface and a single noise source.
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| 20. |
- Ågren, Anders, et al.
(författare)
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Flanking transmission in light weight timber houses with elastic flanking isolators
- 2012
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Ingår i: 41st International Congress and Exposition on Noise Control Engineering, INTER-NOISE 2012. - : AtlasBooks / Institute of Noise Control Engineerin. ; , s. 2289-2300, s. 2289-2300
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Konferensbidrag (refereegranskat)abstract
- There is a strong trend to industrially produce multi-storey light weight timber based houses. This concept allows the buildings to be manufactured to a more or less prefabricated extent. Most common types are volume/room modules or flat wall and floor modules. When assembling the modules at the building site, elastomer isolators are used in several constructions to reduce flanking transmission. The sound insulation demands in the Nordic countries are relatively high and therefore the flanking transmission must be well controlled, elastomer isolators is one choice. Decoupled radiation isolated walls is another. There are though no working studies or mathematical models of the performance of these isolators. They are only treated as simple mass-springs systems that operate vertically. In this paper there is a first approach of an analysis of the structure borne sound isolating performance of elastomer isolators that are separating floors and walls. The performance dependence of structure type is also presented. An empirically based regression model of the insertion loss is derived. The model will be based on measurements of more than ten field installations. In this paper the first three are presented. A goal is that the model can be used for input in future SEN prediction models for modeling of sound insulation.
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