| 1. |
- 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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| 2. |
- 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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| 3. |
- Arvidsson, Emma, et al.
(författare)
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Optimization of sound absorbing ceilings
- 2018
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Ingår i: 47th International Congress and Exposition on Noise Control Engineering (INTERNOISE 2018). - 9781510873032
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Konferensbidrag (refereegranskat)abstract
- The typical acoustical treatment in ordinary rooms such as classrooms, offices, conference rooms etc is an absorbing suspended ceiling. Due to the non-uniform distribution of the absorbing material the sound field at steady-state and during sound decay is far from the ideal conditions assumed in the diffuse field theory. Especially during the sound decay, the degeneration of the sound field emphasizes the shortcomings of the diffuse field assumption. On the other hand, the absorbing properties of sound absorbing ceilings are determined under diffuse field conditions according to the standard ISO 354. The outcome of this measurement in the form of an absorption coefficient is often used as input data in calculation or simulation models. This means that the absorbing properties of the ceilings are characterized under circumstances that are hardly ever encountered in practice. The directional scattering effect of furniture and other interior objects is another circumstance that has to be considered to understand the interaction between the absorbing ceiling and the sound field in rooms with ceiling treatment. In this paper the outline of a project is presented that deals with how to optimize the acoustical properties of ceilings in order to achieve certain room acoustic target values related to reverberation time, speech clarity and sound strength.
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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 7. |
- 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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| 8. |
- 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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| 9. |
- Autio, Hanna, et al.
(författare)
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A statistical method for parameter estimation from Schroeder decay curves
- 2018
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Ingår i: 47th International Congress and Exposition on Noise Control Engineering (INTERNOISE 2018) : Impact of Noise Control Engineering - Impact of Noise Control Engineering. - 9781510873032
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The sound decay curve, measured by either the interrupted noise method or the Schroeder method, can provide relevant information pertaining to a room’s acoustical properties. However, the relevant information is not always readily extractable from the measurements. In this study, measurements of the decay curves of the historically important Vadstena Abbey church in Sweden have been obtained using both of the classical methods. The test building was in normal use with high levels of background noise during the measurements. Aline-fit analysis showed a trend where the Schroeder decay curves yielded a longer estimated reverberation time compared to the interrupted noise method for low frequencies. This indicates that the measurement results are affected by background noise. A statistical model was developed for the Schroeder decay curve in such circumstances. Using it, the maximum likelihood estimates for the deterministic decay parameters can be found even when there are multi-slope decay patterns or significant background noise. The model is straight-forward to implement and can find an estimate for a single-slope decay also when some commercial software fails. The performance for double-slope decay models, as well as a comparison to the results from the interrupted noise method, are analyzed.
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| 10. |
- Autio, Hanna, et al.
(författare)
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An attention-guided algorithm for improving the performance of acoustic simulations
- 2019
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Ingår i: Proceedings of the 23rd International Congress on Acoustics : integrating 4th EAA Euroregio 2019 : 9-13 September 2019 in Aachen, Germany. - 9783939296157 ; , s. 2619-2626
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- When performing acoustic simulations with the purpose of auralization, there is a trade-off between accuracyand speed. In real-time simulations of virtual reality, finding the balance of this trade-off is paramount to achiev-ing the desired result. If successful, the simulation speed is sufficient to provide a seamless acoustic experienceas the agent moves around the space, while still being accurate enough to be realistic. It is generally acceptedthat a 20ms update interval for the impulse response is sufficient for achieving proper interactivity in mostapplications. However, reaching this threshold without degrading the quality of simulation too badly can bechallenging indeed for complex scenes.In this paper, a compromise between interactivity (response time) and accuracy is suggested for raytracing simu-lations. This compromise mimics the behaviour of the listener or the agent, prioritizing speed or accuracy basedon how the agent behaves. When the listener is actively moving around the space, interactivity is prioritized.When the listener stands still, fully immersing in the experience, accuracy is improved. This is achieved byexploiting a fundamental truth of Monte Carlo simulations: Convergence improves with more samples
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