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- Mosharrof, Mohammad Sazzad, et al.
(författare)
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An improved prediction model for the impact sound level of lightweight floors : Introducing decoupled floor-ceiling and beam-plate moment
- 2011
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Ingår i: Acta Acoustica united with Acustica. - 1610-1928 .- 1861-9959. ; 97:2, s. 254-265
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Tidskriftsartikel (refereegranskat)abstract
- To better understand the complex acoustic behaviour of lightweight building structures both experimental and theoretical approaches are necessary. Within the theoretical approach developing theoretical models is of great importance. The aim here is to further develop an existing method to predict the impact sound pressure level in a receiving room for a coupled floor structure where floor and ceiling are rigidly connected by beams. A theoretical model for predicting the impact sound level for a decoupled floor structure, which has no rigid mechanical connections between the floor and the ceiling, is developed. An analytical method has been implemented, where a spatial Fourier transform method as well as the Poisson's sum formula is applied to model transformed plate displacements. Radiated sound power was calculated from these displacements and normalized sound pressure levels were calculated in one-third octave frequency bands. The predicted results from the model are compared with the results from the experiments on the decoupled floor-ceiling construction. The results gave agreements in line with comparisons regarding previous model. The effect of introducing beam-plate moment in the model is studied and is found to be dependent on frequency, showing significant improvement in predicting impact sound level at high frequency region.
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- Mosharrof, Mohammad Sazzad
(författare)
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Study and modelling of lightweight floor structure regarding its acoustic properties
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lightweight floor structure is widely used in building industries and to have better sound insulation builders come up with different ways of construction. Depending on the construction the floor structure could either be coupled (floor and ceiling coupled by beams) or decoupled (no mechanical connection between floor and ceiling). Although there are many models on coupled structure but for decoupled structure the number is not too many. Keeping that in mind the present thesis talks about lightweight floors: the construction, properties, behaviour etc with a focus on developing a model for decoupled floor structure where the core contribution being the decoupling and adding the moment effect at plate beam joints. The advantage of decoupled structure is that it disconnects the sound bridge through the beams. One consequence on the other hand is that cavity resonance dominates the low frequency region. A comparative analysis is also done with the coupled model. While developing the model this talks about different mathematical tools such as Fourier transform, Floquet principle, Poisson's sum formula etc This also gives an overview of different types of modelling technique available such as analytical, Numerical, energy based approach, empirical method etc. A parametric study is also done here to find out the relative influence of different elements on sound pressure level.
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- Pelegrin-Garcia, David, et al.
(författare)
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Measurement and prediction of voice support and room gain in school classrooms
- 2012
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Ingår i: Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 1520-8524 .- 0001-4966. ; 131:1, s. 194-204
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Tidskriftsartikel (refereegranskat)abstract
- Objective acoustic parameters have been measured in 30 school classrooms. These parameters include usual descriptors of the acoustic quality from the listeners’ standpoint, such as reverberation time, speech transmission index, and background noise level, and two descriptors of the acoustic properties for a speaker: Voice support and room gain. This paper describes the measurement method for these two parameters and presents a prediction model for voice support and room gain derived from the diffuse field theory. The voice support for medium-sized classrooms with volumes between 100 and 250 m3 and good acoustical quality lies in the range between _14 and _9 dB, whereas the room gain is in the range between 0.2 and 0.5 dB. The prediction model for voice support describes the measurements in the classrooms with a coefficient of determination of 0.84 and a standard deviation of 1.2 dB.
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