NUMERICAL CALCULATION OF THE DIRECT SOUND TRANSMISSION USING A COMBINED FINITE ELEMENT - STATISTICAL ENERGY ANALYSIS APPROACH

The finite element method and the statistical energy analysis are commonly used to calculate sound transmission in building acoustics. At lower frequencies the finite element method allows an accurate prediction of the modal behaviour of the analysed constructions. Investigations at higher frequencies require a reduction of the maximal element sizes to allow a correct representation of the corresponding wavelengths. As a result the computation times increase and the practical usage of finite element method is limited. Alternatively the statistical energy analysis allows efficient acoustic calculations especially at mid and high frequencies. For this purpose requirements like a sufficient modal density and modal overlap within the investigated frequency bands have to be fulfilled. At low frequencies these requirements cannot be met due to the modal behaviour of the single components of the construction. Taking into account all these aspects, only a combination of both methods leads to calculations covering an extended frequency range at the scope of building acoustics. In this paper, an approach for the combination of these two methods is proposed using a specialized numerical computing environment. The frequency ranges, where the single methods produce reliable results are determined by an advanced analysis of the vibration behaviour of the components. The obtained results are compared to measurements with focus on a comprehensible construction. The investigations show that an appropriate combination of the two calculation methods can lead to efficient and more accurate results. Therefore the applicability of calculations at building acoustics is increased especially for commonly used constructions.