| 1. |
- Andersson, Håkan, et al.
(författare)
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Traceable sound power measurements in essentially diffuse or free fields
- 2016
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Ingår i: Proceedings of the INTER-NOISE 2016 - 45th International Congress and Exposition on Noise Control Engineering. - 9783939296119 ; , s. 6783-6792
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Current methods for the determination of sound power such as the ISO 3740 series do not have a direct traceability to a primary standard. The different methods are regarded as equal, but they do give results with systematic differences. One task of the European project "EMRP JRP SIB 56 SoundPwr" has been to develop and investigate traceable and consistent methods for sound power measurements in essentially diffuse or free fields. By using a calibrated reference sound source as a traceability source, qualification procedures for setups for sound power determinations in different environments have been investigated. Uncertainty sources such as sound field sampling, directivity, frequency content and impedance of the device under test have been analysed. The results are presented in the contribution.
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| 2. |
- Axelsson, Östen
(författare)
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Effects of a low-height sound absorbent street furniture and a fountain on the soundscape in a Stockholm pocket park
- 2016
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Ingår i: Proceedings of the Inter-Noise 2016. - 9783939296119 ; , s. 5203-5211
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Konferensbidrag (refereegranskat)abstract
- This study investigated the effects of a mock-up version of a low-height sound absorbent street furniture and a fountain on the local soundscape in a pocket park in Stockholm. Binaural recordings were conducted at two distances from the main road (on the sidewalk and in the park). The recordings were conducted with or without the mock-up, and with the local fountain either turned on or off. Thirty-two students (16 women, Mage = 26.6 yrs., SDage = 5.7) participated in a listening experiment, and assessed eight experimental sounds, in context of 12 fill sounds, on how pleasant or eventful they were. ANOVA showed that the mock-up had a stronger effect on pleasantness on the sidewalk than in the park, and the fountain contributed to pleasantness only in the absence of the mock-up. Moreover, the fountain reduced the eventfulness in the park but not on the sidewalk. The results are in line with previous case studies. Taken together, they suggest that it is better to build low-height sound absorbent street furniture han fountains, to improve the urban soundscape.
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| 3. |
- Brezas, Spyros, et al.
(författare)
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Dissemination of the unit watt in airborne sound : Aerodynamic reference sound sources as transfer standards
- 2016
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Ingår i: Proceedings of the INTER-NOISE 2016 - 45th International Congress and Exposition on Noise Control Engineering. - 9783939296119 ; , s. 6762-6770
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Konferensbidrag (refereegranskat)abstract
- In the process aiming at the establishment of both traceability and transparent uncertainty budgets for airborne sound power, the dissemination of the unit watt ensures the correct relation between the sound power of a stationary primary standard and the sound power of transportable transfer standards. The paper reports on a detailed study to qualify aerodynamic reference sound sources (RSSs) as transfer standards. The temporal stability of RSSs has been determined for both narrow and broad frequency bands. Specially designed scanning apparatuses have provided directivity results. Remaining room reflections and near field effects have also been studied. The dissemination also requires the prediction of sound power under meteorological (static pressure, ambient temperature) and operating (rotational speed) conditions different from calibration conditions. These influences have been investigated and a correction is proposed. Finally, interlaboratory measurement results of the sound power of an aerodynamic reference sound source are reported.
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| 4. |
- Forssén, Jens, 1968, et al.
(författare)
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A low-height acoustic screen in a setting with an urban road: measured and predicted insertion loss
- 2016
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Ingår i: Proceedings of the INTER-NOISE 2016 - 45th International Congress and Exposition on Noise Control Engineering: Towards a Quieter Future. - 9783939296119 ; , s. 6435-6443
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Konferensbidrag (refereegranskat)abstract
- A low screen was temporarily installed alongside an urban road to test the acoustic performance. Within the on-going project, the screen is an acoustic prototype, whereas later, a screen design will be developed considering also perceived acoustic quality and visual aspects. The current acoustic prototype, built up from concrete modules, was placed beside a small park on the reservation between a two-lane road and a track for walking and cycling. A larger traffic system, of which the two-lane road is a part, determines the daytime equivalent noise level within the urban area. The screen height was about 1.3 m as measured from the level of the road surface and the width of the screen top was 0.3 m. Measurements were carried out both at 20 m distance from the road (within the park) and at 5 m distance from the road (on the cycle track). Insertion loss in maximum level, using controlled light vehicle pass-by at 50 km/h, was measured to 10 dB and 6 dB at 5 and 20 m distance, respectively, at 1.5 m height. The measured results have been compared with those predicted by both a noise mapping software and a boundary element method, showing reasonable agreement.
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| 5. |
- Guglielmone, Claudio, et al.
(författare)
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Main achievements of the EMRP sound power project and future prospects
- 2016
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Ingår i: Proceedings of the INTER-NOISE 2016 - 45th International Congress and Exposition on Noise Control Engineering. - 9783939296119 ; , s. 6811-6817
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Konferensbidrag (refereegranskat)abstract
- An independent method for the measurement of sound power, based on a primary standard traceable to units tied to fundamental constants, has been realised and tested. The most important achievement is that the uncertainty evaluation can be deduced in a direct and (mostly) analytical way from the primary standard and measurement environment parameters, both hemi free and reverberant acoustical fields have been considered. A new traceability line to the primary standard has been established, and the validity of the already available transfer standards has been investigated. All these achievements have the revision of the sound power measurement procedures, for which developments and validation has been carried out during the project, as a goal. Dissemination has been realised by papers, participation in conferences and a seminar. Future work will focus on improvement of the frequency range and uncertainty of the primary standard, establishment of measurement capabilities by means of key comparisons in the EURAMET region, declarations of services in the CIPM database and proposed revision of the ISO standards concerning sound power. Another important task is working among the acoustic industrial and metrological community to foster the acceptance of the new methods. Applications to calibration of microphone arrays are also possible.
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| 6. |
- Höstmad, Patrik, 1974, et al.
(författare)
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Off-peak low noise heavy-duty vehicles, facade insulation and indoor noise disturbance
- 2016
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Ingår i: Proceedings of the INTER-NOISE 2016 - 45th International Congress and Exposition on Noise Control Engineering. - 9783939296119 ; , s. 5258-5266, s. 5258-5266
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Konferensbidrag (refereegranskat)abstract
- Off-peak delivery of goods can result in increased transport efficiency, fuel savings, less pollution and increased traffic safety. However, unless carefully managed it causes increased annoyance and health risks for inhabitants exposed to the transportation noise during hours used for recovery and sleep. The presented work focuses on heavy-duty vehicles with Diesel engines during the "last mile" of the transport corridor through densely populated city centers. The aim is to study preconditions, open questions, and problem areas when nighttime soundscapes are altered by low noise vehicles. By using measured and simulated sounds, different driving conditions and acoustical treatments of vehicles and facade were studied at the facade and indoors in terms of 1/3-octaveband levels and judgments in listening tests. The evaluation shows that low-frequency noise of the vehicles is important indoors, while high-frequency noise is the major contributor outdoors. According to the listening tests the low-frequency noise is coupled to the degree of reported arousal, indicating that reduced low-frequency noise is especially important at nighttime. It was concluded that an acceptable indoor environment was achieved with a modified truck that is driven by a responsible driver, and by using "noise proof" windows with higher sound insulation.
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| 7. |
- Kirbaş, Cafer, et al.
(författare)
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Primary sound power sources for the realisation of the unit watt in airborne sound
- 2016
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Ingår i: Proceedings of the INTER-NOISE 2016 - 45th International Congress and Exposition on Noise Control Engineering. - 9783939296119 ; , s. 6737-6748
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Konferensbidrag (refereegranskat)abstract
- At present, airborne sound power is not a directly measurable quantity. It is calculated from sound pressure measurements performed in special environments, e.g. free or diffuse fields or from sound intensity measurements using 2-microphone probes. All the different methods are lacking traceability and transparent uncertainty budgets. These deficiencies are finally based on the lack of a primary standard for sound power as the metrological basis. In the joint research project funded by the European Metrology Research Program, primary sound power standards were established on the base of the Rayleigh Integral Method where the sound power is calculated from measured velocities on a baffled vibrating body. Different reference sound power sources were designed in different Institutes. The construction of the primary sources was mainly focused on the piston; its material, shape and friction during its movement. Primary sound power sources were installed in hemi anechoic and reverberant environments, and characterisation measurements were performed to see the effect of different environments on the sound power output. Comparison measurements were performed to compare the new and present methods for the primary sound power source.
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| 8. |
- Larsson, Krister
(författare)
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Updated road traffic noise emission models in Sweden
- 2016
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Ingår i: Proceedings of the INTER-NOISE 2016 - 45th International Congress and Exposition on Noise Control Engineering. - 9783939296119 ; , s. 1329-1340
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Konferensbidrag (refereegranskat)abstract
- The Nordic prediction model from 1996 is still used for road traffic noise predictions and noise mapping purposes in many cases in Sweden. The model is restricted to A-weighted levels and the vehicle categories only take light and heavy vehicles into account. Weather conditions and ground effects are simplified. The subsequent Nord2000Road model can be used for noise predictions in more complex situations. Nord2000Road uses third octave bands, an advanced outdoor propagation model and more categories for vehicles and ground. Recently the CNOSSOS-EU model has been developed in Europe and can be used for noise mapping purposes according to the European Noise Directive in the future. CNOSSOS-EU uses octave bands and similar vehicle categories as Nord2000Road. The source model as well as the propagation model differs from Nord2000Road. In 2015, a measurement campaign of noise emission in real traffic was conducted in Sweden. This paper presents updated input data for the Nord2000Road source model as well as national Swedish correction terms for rolling noise in the CNOSSOS-EU model to better represent the recent measurement results.
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| 9. |
- Lundén, Peter, et al.
(författare)
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On urban soundscape mapping : A computer can predict the outcome of soundscape assessments
- 2016
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Ingår i: Proceedings of the INTER-NOISE 2016 - 45th International Congress and Exposition on Noise Control Engineering. - 9783939296119 ; , s. 4725-4732
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Konferensbidrag (refereegranskat)abstract
- The purpose of this study was to investigate whether or not a computer may predict the outcome of soundscape assessments, based on acoustic data only. It may be argued that this is impossible, because a computer lack life experience. Moreover, if the computer was able to make an accurate prediction, we also wanted to know what information it needed to make this prediction. We recruited 33 students (18 female; Mage = 25.4 yrs., SDage = 3.6) out of which 30 assessed how pleasant and eventful 102 unique soundscape excerpts (30 s) from Stockholm were. Based on the Bag of Frames approach, a Support Vector Regression learning algorithm was used to identify relationships between various acoustic features of the acoustics signals and perceived affective quality. We found that the Mel-Frequency Cepstral Coefficients provided strong predictions for both Pleasantness (R2 = 0.74) and Eventfulness (R2 = 0.83). This model performed better than the average individual in the experiment in terms of internal consistency of individual assessments. Taken together, the results show that a computer can predict the outcome of soundscape assessments, which is promising for future soundscape mapping.
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