| 1. |
- Nilsson, Erik, et al.
(författare)
-
Effect of Bearing Direction and Mounting Techniques on Cross-Laminated Timber Elements in the Field
- 2022
-
Ingår i: Internoise 2022 - 51st International Congress and Exposition on Noise Control Engineering. - 9781906913427
-
Konferensbidrag (refereegranskat)abstract
- Vibration reduction index (Kij ) measurements in the field have some challenges compared to laboratory measurements. Firstly, the measurement requires access to a construction site during the short time span when the cross-laminated timber (CLT) elements are apparent. Secondly, building contractors are often on a tight time schedule. Therefore, it is important to find a solution that minimizes the measurement time on site. Moreover, Kij measurements in the field include several types of junctions with different bearing directions which may be of importance. This paper aims to evaluate two different mounting techniques with accelerometers on CLT elements and to discuss how the bearing direction could affect the vibration level difference of junctions. Measurement data indicate few deviations between mounting techniques with bee wax or double-sided adhesive tape when accelerometers are attached to CLT elements. Furthermore, field measurements indicate that the vibration level will decrease with increased lamellas over the same CLT element. Double-sided adhesive tape is an adequate substitute for bee wax in the field for mounting accelerometers on CLT elements, with some limitations at high frequencies. Measurement data concludes that the bearing direction of CLT elements can influence the vibration reduction index of a junction.
|
|
| 2. |
- Arvidsson, Emma, et al.
(författare)
-
Acoustic design of ordinary rooms using absorbers and diffusers
- 2020
-
Ingår i: Proceedings of 2020 International Congress on Noise Control Engineering, INTER-NOISE 2020. - 9788994021362
-
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.
|
|
| 3. |
- Arvidsson, Emma, et al.
(författare)
-
Quantification of the absorption and scattering effects of diffusers in a room with absorbent ceiling
- 2021
-
Ingår i: Buildings. - : MDPI AG. - 2075-5309. ; 11:12
-
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.
|
|
| 4. |
- Arvidsson, Emma, et al.
(författare)
-
Subjective experience of speech depending on the acoustic treatment in an ordinary room
- 2021
-
Ingår i: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1661-7827 .- 1660-4601. ; 18:23
-
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.
|
|
| 5. |
- Autio, Hanna, et al.
(författare)
-
An Iterative Ray Tracing Algorithm to Increase Simulation Speed While Maintaining Overall Precision
- 2023
-
Ingår i: Acoustics. - : MDPI AG. - 2624-599X. ; 5:1, s. 320-342
-
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.
|
|
| 6. |
- Autio, Hanna, et al.
(författare)
-
Auralization as a tool of historic reconstruction of Vadstena Abbey church
- 2019
-
Ingår i: InterNoise 19, Madrid, Spain. - 0736-2935. - 9788487985317 ; , s. 3970-3981
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Throughout human history, there have been locations used for performance of speech and music. Many of these locations are considered part of our common cultural heritage, and more and more of them can be visited virtually as technology advances to produce better and better reconstructions. However, the technological capabilities are not the only limitations when it comes to historical reconstruction, and one of the most important research questions is often to determine the actual historical configuration of a space. This is the case for a project regarding Vadstena Abbey church in Sweden. As a step in producing the virtual reconstruction, a number of different configurations for one of the major performance locations will be examined using acoustic simulations and auralizations. As the acoustic properties of a space affects the performances within it, there should be a correspondence between the musical and oral traditions of this location in particular and its acoustics. Historical records of the performance traditions within the space, as well as records of the acoustic experiences of visitors, will be used as an evaluation tool to distinguish between the models.
|
|
| 7. |
- Autio, Hanna, et al.
(författare)
-
The influence of different scattering algorithms on room acoustic simulations in rectangular rooms
- 2021
-
Ingår i: Buildings. - : MDPI AG. - 2075-5309. ; 11:9
-
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.
|
|
| 8. |
- Bader Eddin, Mohamad, et al.
(författare)
-
Prediction of Sound Insulation Using Artificial Neural Networks—Part II : Lightweight Wooden Façade Structures
- 2022
-
Ingår i: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 12:14
-
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.
|
|
| 9. |
- Bard, Delphine, et al.
(författare)
-
Silent timber build - modelling acoustic characteristics of timber structures
- 2017
-
Ingår i: INTER-NOISE 2017 - 46th International Congress and Exposition on Noise Control Engineering : Taming Noise and Moving Quiet - Taming Noise and Moving Quiet.
-
Konferensbidrag (refereegranskat)abstract
- In year 2017 the WWN+ project "Silent Timber Build" is finishing. The project focused on studying timber structures with regard to their sound insulation characteristics, both airborne sound insulation and impact sound insulation. The aim is to develop calculation models (and / or to provide input to standardized models) for various timber structures available in Europe but also to facilitate future optimization of buildings using wood as structural bearing system. Divided into several subprojects, an efficient managing of the project was possible. In one part of the project, current timber structures are "grouped", considering their acoustical behaviour and their various compositions. Another part of the project was to use the grouping in order to develop and refine general prediction models by using FEM in combination with an SEA software that was included in the project from start. Throughout the project, the software was refined and adapted to typical building structures and groups. By comparing laboratory measurement results with calculated results, improvements of the software successively were introduced. The aim at the end is to deliver a calculation tool adapted to future sound insulation requirements in multi storey residential units, e.g. The accuracy of the model has to fit to the frequencies that causes annoyance. Additionally Silent Timber Build models are used in order to design some of the timber structures presented in the European Database available at www.lignum.ch. In this database a listening tool is integrated, making it easier for users to translate acoustical figures to hearing impression. Specifically, this paper comprises a description of the project and its main results but also some significant examples of calculated floor assemblies and wall assemblies. It also summarizes some main difficulties as modelling timber structures and finally recommendations for future development of the wooden industry.
|
|
| 10. |
- Eddin, Mohamad Bader, et al.
(författare)
-
Prediction of Sound Insulation Using Artificial Neural Networks—Part I : LightweightWooden Floor Structures
- 2022
-
Ingår i: Acoustics. - : MDPI AG. - 2624-599X. ; 4:1, s. 203-226
-
Tidskriftsartikel (refereegranskat)abstract
- The artificial neural networks approach is applied to estimate the acoustic performance for airborne and impact sound insulation curves of different lightweight wooden floors. The prediction model is developed based on 252 standardized laboratory measurement curves in one-third octave bands (50-5000 Hz). Physical and geometric characteristics of each floor structure (materials, thickness, density, dimensions, mass and more) are utilized as network parameters. The predictive capability is satisfactory, and the model can estimate airborne sound better than impact sound cases especially in the middle-frequency range (250-1000 Hz), while higher frequency bands often show high errors. The forecast of the weighted airborne sound reduction index Rw was calculated with a maximum error of 2 dB. However, the error increased up to 5 dB in the worse case prediction of the weighted normalized impact sound pressure level Ln,w. The model showed high variations near the fundamental and critical frequency areas which affect the accuracy. A feature attribution analysis explored the essential parameters on estimation of sound insulation. The thickness of the insulation materials, the density of cross-laminated timber slab and the concrete floating floors and the total density of floor structures seem to affect predictions the most. A comparison between wet and dry floor solution systems indicated the importance of the upper part of floors to estimate airborne and impact sound in low frequencies.
|
|
