A Contribution concerning Boundary Condition Effects that need to be considered using SEA for Calculation of Direct Sound Transmission

The use of the statistical energy analysis (SEA) for calculations in building acoustics is increasing, especially for predictions of the sound insulation of timber-based constructions. The accuracy of the calculation results depends amongst others on the quality of input parameters like material data, as well as on the considered boundary conditions and physical effects. In this paper, the deviation between measured and predicted sound insulation is analysed and the underlying physical effects are determined, based on additional comprehensive investigations. One layer of gypsum fibreboard has been chosen as a test specimen, which shows a reproducible vibrational behaviour. In a first step, suitable values for the material properties are determined. Then, several investigations, based on measurements, are described, which have been carried out in a testing facility, that complies with EN ISO 10140 standard series. The investigations show that some of the observed deviations between measurement and calculation results may be wrongly considered to be an SEA-model-error. The differences are primary caused by a couple of physical effects influencing the measured reference data. As a consequence of the analysis, the boundary conditions of the measurement setup have been adapted with success – an obvious reduction of the deviation between measured and calculated data could be achieved.