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- Arvidsson, Emma, et al.
(författare)
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Acoustic design of ordinary rooms using absorbers and diffusers
- 2020
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Ingår i: Proceedings of 2020 International Congress on Noise Control Engineering, INTER-NOISE 2020. - 9788994021362
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Konferensbidrag (refereegranskat)abstract
- With different activities in a room, room acoustic requirements differ and when the acoustic requirements are different, acoustic treatment must be adapted. This study focuses on room acoustics in ordinary public rooms such as classrooms and offices. By tradition the acoustic treatment in these rooms is an absorbent ceiling. Experiments have been carried out in a classroom where the baseline in the acoustic treatment was a highly absorptive acoustic ceiling. This treatment has then been combined with different configurations of diffusers and wall absorbers where the coverage and pattern of the different treatments has been tested to evaluate their effect on the room acoustic parameters. Furthermore, several configurations with different diffuser directionality have been evaluated. The room acoustic parameters reverberation time, speech clarity and sound strength were assessed. The results show a clear correspondence in the room acoustic parameters for the different treatments used, as well as a frequency dependence. Here we discuss the interpretation of these results and how this new information can be used to obtain the room acoustic requirements for a specific activity.
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- Arvidsson, Emma, et al.
(författare)
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Diffusers in public ordinary rooms
- 2019
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Ingår i: InterNoise 19, Madrid, Spain. - 9788487985317 ; , s. 5453-5461
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Traditionally, the room acoustic properties in an ordinary public room are defined by only one parameter, the reverberation time. However, research has showed that additional room acoustic parameters as sound strength and speech clarity are necessary to consider in order to achieve good acoustic conditions. In a room with acoustical ceiling treatment the effects of furniture and interiors on the room acoustic parameters are significant. In addition, by using diffusers with directional properties it is possible to individually control the room acoustic parameters. Room acoustical measurements have been carried out in a reverberation chamber with suspended absorbing ceiling and directional diffusing objects. The effect of different diffuser configurations has been examined regarding reverberation time, speech clarity and sound strength. The evaluation shows that the orientation and the amount of the diffusing elements have a significant influence on the room acoustic parameters and can be used to fine-tune the acoustical conditions in public ordinary rooms with an existing acoustic ceiling treatment. This paper presents a study showing how diffusers can be used to contribute to an improved sound environment in public ordinary rooms with an acoustic ceiling.
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- Arvidsson, Emma, et al.
(författare)
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Pattern and orientation of diffusers in rooms with an absorbent ceiling
- 2019
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Ingår i: Proceedings of the 23rd International Congress on Acoustics : Integrating 4th EAA Euroregio 2019 - Integrating 4th EAA Euroregio 2019. - 2226-7808 .- 2415-1599. - 9783939296157 ; 2019-September, s. 2281-2288
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Konferensbidrag (refereegranskat)abstract
- Lately have the demands on good room acoustics in public ordinary rooms increased. Traditionally has only reverberation time been considered in this type of rooms but complementary parameters as sound strength and speech clarity are more commonly used today. This trend naturally implies higher demands on the acoustic treatment. Typical for public ordinary rooms is to use an absorbent ceiling. One way to further improve the acoustic properties is to complement the ceiling treatment with diffusers. To investigate the effect of combining these two types of acoustic treatments have measurements been carried out combing different setups of diffusers in a reverberant room with an absorbent ceiling. The impact on reverberation time, speech clarity and sound strength has been studied. In this paper we present how diffusers can be used in order to improve the acoustic properties in a public ordinary room with an absorbent ceiling and how the pattern and orientation of diffusers can be used to adjust different acoustic parameters.
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- Arvidsson, Emma, et al.
(författare)
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Quantification of the absorption and scattering effects of diffusers in a room with absorbent ceiling
- 2021
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Ingår i: Buildings. - : MDPI AG. - 2075-5309. ; 11:12
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Tidskriftsartikel (refereegranskat)abstract
- In ordinary public rooms, such as classrooms and offices, an absorbent ceiling is the typical first acoustic action. This treatment provides a good acoustic baseline. However, an improvement of specific room acoustic parameters, operating for specific frequencies, can be needed. It has been seen that diffusing elements can be effective additional treatment. In order to choose the right design, placement, and quantity of diffusers, a model to estimate the effect on the acoustics is necessary. This study evaluated whether an SEA model could be used for that purpose, particularly for the cases where diffusers are used in combination with an absorbent ceiling. It was investigated whether the model could handle different quantities of diffusing elements, varied diffusion characteristics, and varied installation patterns. It was found that the model was sensitive to these changes, given that the output from the model in terms of acoustic properties will be reflected by the change of diffuser configuration design. It was also seen that the absorption and scattering of the diffusers could be quantified in a laboratory environment: a reverberation chamber. Through the SEA model, these quantities could be transformed to a full-scale room for estimation of the room acoustic parameters.
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| 7. |
- Arvidsson, Emma, et al.
(författare)
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Subjective experience of speech depending on the acoustic treatment in an ordinary room
- 2021
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1661-7827 .- 1660-4601. ; 18:23
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Tidskriftsartikel (refereegranskat)abstract
- In environments such as classrooms and offices, complex tasks are performed. A satisfac-tory acoustic environment is critical for the performance of such tasks. To ensure a good acoustic environment, the right acoustic treatment must be used. The relation between different room acoustic treatments and how they affect speech perception in these types of rooms is not yet fully under-stood. In this study, speech perception was evaluated for three different configurations using ab-sorbers and diffusers. Twenty-nine participants reported on their subjective experience of speech in respect of different configurations in different positions in a room. They judged sound quality and attributes related to speech perception. In addition, the jury members ranked the different acoustic environments. The subjective experience was related to the different room acoustic treatments and the room acoustic parameters of speech clarity, reverberation time and sound strength. It was found that people, on average, rated treatments with a high degree of absorption as best. This configura-tion had the highest speech clarity value and lowest values for reverberation time and sound strength. The perceived sound quality could be correlated to speech clarity, while attributes related to speech perception had the strongest association with reverberation time.
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| 8. |
- Arvidsson, Emma, et al.
(författare)
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The Difference in Subjective Experience Related to Acoustic Treatments in an Ordinary Public Room : A Case Study
- 2021
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Ingår i: Acoustics. - : MDPI AG. - 2624-599X. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- In ordinary public rooms absorbent ceilings are normally used. However, reflective material such as diffusers can also be useful to improve the acoustic performance for this type of environment. In this study, different combinations of absorbers and diffusers have been used. The study investigates whether a test group of 29 people perceived sound in an ordinary room differently depending on the type of treatment. Comparisons of the same position in a room for different configurations as well as different positions within one configuration were made. The subjective judgements were compared to the room acoustic measures T20, C50 and G and the difference in the values of these parameters. It was found that when evaluating the different positions in a room, the configuration including diffusers was perceived to a greater extent as being similar in the different positions in the room when compared to the configuration with absorbers on the walls. It was also seen that C50 was the parameter that mainly affected the perception, with the difference needing to be 2 dB to recognize a difference. However, the room acoustic measurements could not fully explain the differences obtained in perception. In addition, the subjective sound image created by different types of treatments was also shown to have an important impact on the perception.
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| 9. |
- Arvidsson, Emma, et al.
(författare)
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The Effect on Room Acoustical Parameters Using a Combination of Absorbers and Diffusers : An Experimental Study in a Classroom
- 2020
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Ingår i: Acoustics. - : MDPI AG. - 2624-599X. ; 2:3
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Tidskriftsartikel (refereegranskat)abstract
- Several room acoustic parameters have to be considered in ordinary public rooms, such as offices and classrooms, in order to present the actual conditions, thus increasing demands on the acoustic treatment. The most common acoustical treatment in ordinary rooms is a suspended absorbent ceiling. Due to the non-uniform distribution of the absorbent material, the classical diffuse field assumption is not fulfilled in such cases. Further, the sound scattering effect of non-absorbing objects such as furniture are considerable in these types of rooms. Even the directional characteristic of the sound scattering objects are of importance. The sound decay curve in rooms with absorbent ceilings often demonstrate a double slope. Thus, it is not possible to use reverberation time as room parameter as a representative standalone acoustic measure. An evaluation that captures the true room acoustical conditions therefore needs supplementary parameters. The aim of this experimental study is to show how various acoustical treatments affect reverberation time T20, speech clarity C50 and sound strength G. The experiment was performed in a mock-up of a classroom. The results demonstrated how absorbers, diffusers and scattering objects influence room acoustical parameters. It is shown that to some extent the parameters can be adjusted individually by using different treatments or combination of treatments. This allows for the fine-tuning of the acoustical conditions, in order to fulfill the requirements for achieving a high-quality sound environment.
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| 10. |
- Bakhshi, Bamdad, 1970, et al.
(författare)
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Experimental observation of soliton robustness to polarisation dispersion pulse broadening
- 1999
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 35:1, s. 65-66
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Tidskriftsartikel (refereegranskat)abstract
- Soliton robustness to polarisation dispersion pulse broadening in a 400km installed optical fibre is experimentally demonstrated. With 10ps input pulses and a differential group delay of 7.6ps, the soliton pulsewidth at the receiver is maintained within 10-11ps when the input polarisation is changed, while the corresponding range for dispersion-compensated linear pulses is 10.5-15.5ps.
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