| 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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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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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- Autio, Hanna, et al.
(författare)
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An Iterative Ray Tracing Algorithm to Increase Simulation Speed While Maintaining Overall Precision
- 2023
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Ingår i: Acoustics. - : MDPI AG. - 2624-599X. ; 5:1, s. 320-342
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Tidskriftsartikel (refereegranskat)abstract
- Ray tracing is a frequently used method for acoustic simulations, valued for its calculation speed and ease of use. Although it is fast, there are no fully ray tracing-based real-time simulation methods or engines. Under real-time restrictions, ray tracing simulations lose precision and the variance inherent in the random simulation method has too much impact on the outcome. In this paper, an algorithm called iterative ray tracing is presented that reduces the negative effects of real-time restrictions by iteratively improving the initial calculation and increasing the precision over time. In addition, new estimates of the expected value and variance of ray tracing simulations are presented and used to show the iteration steps in the new algorithm reduce variance, while maintaining the expected value. Simulations using iterative ray tracing are compared to measurements and simulations using the classical ray tracing method, and it is shown that iterative ray tracing can be used to improve precision over time. Although more testing is needed, iterative ray tracing can be used to extend most ray tracing algorithms, in order to decrease the adverse effects of real-time restrictions.
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| 7. |
- Autio, Hanna, et al.
(författare)
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Historically Based Room Acoustic Analysis and Auralization ofa Church in the 1470s
- 2021
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Ingår i: Applied Sciences. - : MDPI. - 1454-5101 .- 2076-3417. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- Worship space acoustics have been established as an important part of a nation’s cultural heritage and area of acoustic research, but more research is needed regarding the region of northern Europe. This paper describes the historical acoustics of an important abbey church in Sweden in the 1470s. A digital historical reconstruction is developed. Liturgical material specific to this location is recorded and auralized within the digital reconstruction, and a room acoustic analysis is performed. The analysis is guided by liturgical practices in the church and the monastic order connected to it. It is found that the historical sound field in the church is characterized by the existence of two distinct acoustical subspaces within it, each corresponding to a location dedicated to the daily services of the monastical congregations. The subspaces show significantly better acoustic conditions for liturgical activities compared to the nave, which is very reverberant under the conditions of daily services. Acoustic transmission from the two subspaces is limited, indicating that the monastic congregations were visually and acoustically separated from the visitors in the nave and each other.
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| 8. |
- Autio, Hanna, et al.
(författare)
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The influence of different scattering algorithms on room acoustic simulations in rectangular rooms
- 2021
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Ingår i: Buildings. - : MDPI AG. - 2075-5309. ; 11:9
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Tidskriftsartikel (refereegranskat)abstract
- Raytracing is a widespread tool for room acoustic simulations, and one of its main advan-tages is the inclusion of surface scattering. Although surface scattering has been acknowledged as a central aspect of accurate raytracing simulations for many years, there is ongoing research into its effects and how to implement it better. This study evaluates three different algorithms for surface scattering in raytracers, referred to as on–off scattering, perturbation scattering, and diffuse field scattering. Their theoretical foundation is discussed, and the physical accuracy of the resulting simulations is evaluated by comparing simulated room acoustic parameters to measurements. It is found that the choice of surface scattering algorithm has a significant impact on the simulation outcomes, both in terms of physical accuracy and in terms of usability. Additionally, there are differences in the parametrization of surface scattering depending on the algorithm chosen. Of the three tested algorithms, the most commonly used algorithm (on–off scattering) seems to have the best properties for simulations.
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| 9. |
- Bader Eddin, Mohamad, et al.
(författare)
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A sound insulation prediction model for floor structures in wooden buildings using neural networks approach
- 2021
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Ingår i: Proceedings of INTER-NOISE 2021 - 2021 International Congress and Exposition of Noise Control Engineering. - 0736-2935. - 9781732598652
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Reliable prediction tools are yet to be developed for estimating the accurate acoustic performance of lightweight structures, which are vital especially in the design process. This paper presents a sound insulation prediction model based on artificial Neural Networks (NN) to estimate acoustic performance for airborne and impact sound insulation of floor structures. At an initial stage, the prediction model was developed and tested for a small amount of data, specifically 67 laboratory measurement curves in one third octave bands. The results indicate that the model can predict the weighted airborne reduction index Rw for various floors with a maximum error of 1 dB. The accuracy decreases with errors up to 9 dB for the weighted index for impact sound Ln,w, in cases of complex floor configurations due to large error deviations in high frequency bands between the real and estimated values. The model also shows a very good accuracy in predicting the airborne and impact sound insulation curves in the low frequencies, which are of higher interest usually in building acoustics.
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| 10. |
- Bader Eddin, Mohamad, et al.
(författare)
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Prediction of Sound Insulation Using Artificial Neural Networks—Part II : Lightweight Wooden Façade Structures
- 2022
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Ingår i: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 12:14
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Tidskriftsartikel (refereegranskat)abstract
- A prediction model based on artificial neural networks is adapted to forecast the acoustic performance of airborne sound insulation of various lightweight wooden façade walls. A total of 100 insulation curves were used to develop the prediction model. The data are laboratory measurements of façade walls in one-third-octave bands (50 Hz–5 kHz). For each façade wall, geometric and physical information (material type, dimensions, thicknesses, densities, and more) are used as input parameters. The model shows a satisfactory predictive capability for airborne sound reduction. A higher accuracy is obtained at middle frequencies (250 Hz–1 kHz), while lower and higher frequency ranges often show higher deviations. The weighted airborne sound reduction index ((Formula presented.)) of façades can be estimated with a maximum difference of 3 dB. Sometimes, the model shows high variations within fundamental and critical frequencies that influence the predictive precision. A sensitivity analysis is implemented to investigate the significance of parameters in insulation estimations. The material density (i.e., cross-laminated timber panel, gypsum board), thickness of the insulation materials, thickness and spacing between interior studs and the total density of façades are factors of significant weight on predictions. The results also emphasize the importance of façade thickness and the total density of the clustered exterior layers.
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