| 1. |
- Hoever, Carsten, 1979, et al.
(författare)
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Waveguide-Finite-Element based parameter study of car tyre rolling losses
- 2011
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Ingår i: Proceedings - 6th Forum Acusticum 2011, Aalborg, 27 June - 1 July 2011. - 2221-3767. - 9788469415207 ; , s. 789-794
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Konferensbidrag (refereegranskat)abstract
- Low rolling resistance and a low noise level are two characteristics of a car tyre which are often seen as conflicting with each other. Simultaneously, there is an increased demand for improvement in both fields due to legislative changes. Due to the fact that there is little to no detailed information available on the relation between rolling resistance and acoustical behaviour of car tyres, an in-depth investigation of this subject seems to be desirable. In a first step, a Waveguide-Finite-Element-Model (WFEM) of a car tyre is combined with a non-linear 3D contact model to calculate the resulting contact forces between tyre and road surface. This can be used to make a detailed prediction of the tyre vibrations. For steady state rolling the input power into the tyre at the tyre-road interface gives the rolling resistance in terms of dissipated power. This includes detailed information on frequency and wave order distribution of dissipation. Using a parameter study, it is evaluated how the rolling resistance is affected by material properties or the tyre design.
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| 2. |
- Winroth, Julia, 1981, et al.
(författare)
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Influence of tread inertia during deformation using a detailed numerical tyre/road contact model
- 2011
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Ingår i: Proceedings - 6th Forum Acusticum 2011, Aalborg, 27 June - 1 July 2011. - 2221-3767. - 9788469415207 ; , s. 2431-2434
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Konferensbidrag (refereegranskat)abstract
- Predicting tyre/road interaction processes like stick-slip and stick-snap and their resulting tyre/road noise requires detailed information about the road surface and the dynamics of the tread at the interface. Inertial effects in the tread layer are neglected in many of the existing tyre/road interaction models without explicit justification. The objective of this paper is to investigate the potential importance of these effects for the case of a tread material indenting a rough road surface in the normal direction. A comprehensive numerical contact model operating in the time-domain which includes the effects of interfacial details is used for this purpose. Contact forces at the surface of the tread and at the interface between the tread and the belt are studied in the normal direction during the simulated loading. The inertial case, with a tread impulse response extending in time, is compared with the non-inertial case where the corresponding quasi-static response is used. Results show that the difference in contact force and contact stiffness between a quasi static and a dynamic simulation is small for loading rates that could be found in typical tyre/road contact conditions. Only for extremely high loading rates is there a significant difference. This work implies that inertial effects of the tread are negligible for the local tread response when simulating normal tyre/road contact situations.
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| 3. |
- Amiryarahmadi, Nata, 1982, et al.
(författare)
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Subjective evaluation of impact sound from footsteps
- 2023
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Ingår i: Proceedings of Forum Acusticum. - : European Acoustics Association, EAA. - 2221-3767. ; , s. 2467-
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Konferensbidrag (refereegranskat)abstract
- Low-frequency impact sound caused by upstairs neighbors walking on the floor is a key acoustic challenge regarding lightweight floors and a major source of disturbance particularly in wooden buildings. To investigate the effect of floor design on the perceived walking sound, a virtual design tool has been developed, which allows for auralising the impact sounds containing low frequencies down to 20 Hz. Using this tool, footstep sounds on 10 different lightweight floors were auralised by a loudspeaker grid mounted in the ceiling of an acoustically controlled lab, which is furnished as a common living room. The walking sounds were subjectively evaluated through listening tests while the subjects were sitting freely on a sofa without needing to use any extra listening equipment. The listening test results suggest that loudness, thumpiness and reverberation are correlated with the perceived annoyance. The results also indicate a correlation between annoyance and age as well as the individual experience of earlier exposure to noise.
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| 4. |
- Amiryarahmadi, Nata, 1982, et al.
(författare)
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Time-domain model of a tapping machine
- 2011
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Ingår i: Proceedings - 6th Forum Acusticum 2011, Aalborg, 27 June - 1 July 2011. - 2221-3767. ; , s. 1713-1718
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Konferensbidrag (refereegranskat)abstract
- In the past few years the use of lightweight buildings made of prefabricated wooden elements has become more common. Ease of installation, high accuracy and lightness of such buildings has attracted builders and designers. Sweden, having a large coverage of renewable forests has an increasing interest in multi-storey wooden buildings. However noise and vibration in wooden buildings is an issue of concern especially low frequency impact sound due to footsteps. Impact sound insulation of floors can be measured based on ISO 140-7 using standardized tapping machine as excitation source. Experience has shown that in many cases the results obtained by this method do not correlate with annoyance experienced by inhabitants. On the other hand, the method presented in ISO 140-7 has usually shown to be relevant for the evaluation of impact sound transmission of concrete floors. Discovering the source of this contradiction requires deeper understanding of the impact process. A first step would be to find the difference between contact forces of the tapping machine on different floor materials. One could then correlate it with inhabitants’ perceived annoyance. This paper is the first step of this investigation which is a part of a Swedish research project called AkuLite. In this work a time-dependent model based on Hertz’s contact law is presented for the tapping machine. The model is validated by measurements on a homogeneous concrete floor. Also the contribution of parameters such as damping and stiffness of floor material on the resulting impact force and vibrations is studied.
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| 5. |
- Bergman, Penny, 1982, et al.
(författare)
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Sound preference as a moderator to restorative environments
- 2011
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Ingår i: Proceedings - 6th Forum Acusticum 2011, Aalborg, 27 June - 1 July 2011. - 2221-3767. ; , s. 1065-1068
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Konferensbidrag (refereegranskat)abstract
- With increased stressful situations in the society the demands for restorative environments with a high ability to reduce stress increase. Studies of urban soundscapes have mainly focused on what kind of sounds that cause annoyance, or increase stress. Fewer have addressed the opposite: how may sound decrease perceived stress levels? Visual modality studies show a high correlation between preferred environments and their ability to reduce stress levels. Hypothetically the same should apply within the auditory modality. In order to study the possible effect of preferred sounds as a moderator for stress reduction: 24 participants were exposed to a stress inducing computer game and a subsequent rest while listening to either preferred or non-preferred sounds. The sounds were environmental sounds and rated by each participant in terms of preference before the experiment started. Experienced stress was measured right after the stress induction and after 20 minute long rests. The results show a significant decrease of perceived stress when exposed to preferred environmental sounds. When listening to the less preferred sounds during the rest there was no significant reduction of perceived stress. The results will be discussed in relation to theories of emoacoustics and attention restoration.
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| 6. |
- Helmholz, Hannes, 1990, et al.
(författare)
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Instrumental Evaluation of Sensor Self-Noise in Binaural Rendering of Spherical Microphone Array Signals
- 2020
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Ingår i: Proceedings of Forum Acusticum. - 2221-3767. ; , s. 1349-1356
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Konferensbidrag (refereegranskat)abstract
- Spherical microphone arrays are used to capture spatial sound fields, which can then be rendered via headphones. Insight into perceptual properties of sensor self-noise is valuable in the design and construction process of such arrays. We use the Real-Time Spherical Array Renderer (ReTiSAR) to analyze the frequency-dependent white-noise-gain, i.e. propagation of wanted and unwanted signals through the processing pipeline. In this contribution, we demonstrate an instrumental evaluation for a large set of array and rendering configurations. Latter strongly influence the rendered spectral balance and overall level of spatially uniformly distributed self-noise. Additionally, a dependency on head rotation yielding a change in the reproduced coloration is confirmed for the case of spatially non-uniform noise.
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| 7. |
- Kropp, Wolfgang, 1959, et al.
(författare)
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BUILDING ACOUSTICS AND THE “MILLION PROGRAMME” IN SWEDEN
- 2023
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Ingår i: Proceedings of Forum Acusticum. - 2221-3767.
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Konferensbidrag (refereegranskat)abstract
- The paper focus on the development of building acoustics in Sweden exemplified by the activities at Chalmers University of Technology. Developments are often initiated by incidences where people meet at a place in a certain context. So also happened in Sweden in the middle of the forties when Per Bruel came as refugee from the German occupied Denmark to Chalmers where he started the Chalmers Acoustic Laboratory. He was soon joined by Uno Ingård who later was professor at MIT. At that time Sweden was in a transformation process from an agrarian to a highly industrialized nation leading to a large urbanization. Shortage of housing and the need to increase housing standard led to the so-called million programme with the goal to build one million flats. New building technologies (e.g., light concrete walls or the use of prefabricated elements) as well as the need/wish for cost efficiency led however to buildings of varying quality with new challenges with respect to building acoustics. As consequence building acoustics was identified as important part in the education of civil engineers and in 1962 Chalmers established a professorship in building acoustics. In 1969 Tor Kihlman became the first professor in building acoustics in Sweden.
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| 8. |
- Kropp, Wolfgang, 1959, et al.
(författare)
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Sound radiation of a rolling tyre
- 2011
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Ingår i: Proceedings - 6th Forum Acusticum 2011, Aalborg, 27 June - 1 July 2011. - 2221-3767. ; , s. 795-800
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Konferensbidrag (refereegranskat)abstract
- In this work an advanced tyre model based on Wave Guide Finite Elements is used in connection with a contact model and a radiation model in order to investigate the sound radiation from a rolling tyre. With these tools a slick tyre rolling on an ISO and a rough surface is simulated. Based on the calculated contact forces in the time domain the amplitudes of the modes excited during rolling are determined as function of frequency. A boundary element model is then applied to predict the sound pressure level on a reference surface around a tyre placed on rigid ground as function of the modal composition of the tyre vibrations. Taking into account different modes when calculating the vibrational field as input into the boundary element calculations, it is possible to identify individual modes or groups of modes of special relevance for the radiated sound power. The results show that mainly low-order modes with relative low amplitudes but high radiation efficiency in the frequency range between 800 and 1200 Hz are responsible for the radiated sound power at these frequencies, while those modes which are most strongly excited in that frequency range during rolling are irrelevant for the radiated sound power. This fact is very essential when focusing on the design of quieter tyres.
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| 9. |
- Peplow, A., et al.
(författare)
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Exterior Auralization of Traffic Noise within the LISTEN project
- 2011
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Ingår i: Proceedings - 6th Forum Acusticum 2011, Aalborg, 27 June - 1 July 2011. - : European Acoustical Association. - 2221-3767. ; , s. 665-669
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In the present paper, computational auralizations of a single pass-by of a passenger car and passenger train are investigated. Auralization of future traffic noise scenarios would be a valuable tool for city planners, noise consultants and decision makers, since it would make it possible to evaluate various noise mitigation solutions already at the planning stage. The main goal of the Swedish multidisciplinary research project LISTEN has been to develop such a tool. This paper reports recent listening experiments conducted to perceptually evaluate the auralizations and subsequent improvements on computational methodologies regarding road and rail traffic noise and passenger train source models.
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| 10. |
- Rietdijk, Frederik, 1988, et al.
(författare)
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Modelling sound propagation in the presence of atmospheric turbulence for the auralisation of aircraft noise
- 2014
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Ingår i: Proceedings of Forum Acusticum. - 2221-3767. - 9788361402282 ; 2014-January
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Konferensbidrag (refereegranskat)abstract
- A new tool for the auralisation of aircraft noise in an urban environment is in development. When lis-tening to aircraft noise sound level fluctuations caused by atmospheric turbulence are clearly audible.Therefore, to create a realistic auralisation of aircraft noise, the influence of atmospheric turbulenceon sound propagation needs to be included. Presented is a model in development for including fluctuations due to movement through a frozen turbulent atmosphere in an auralisation.
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