Author(s): Buchegger Blasius, Ferk Heinz, Schanz Martin
Improving the flanking sound insulation performance of timber based constructions at low frequencies is a big challenge, mostly caused by the low mass of the material timber. Additional linings on the walls increase the sound insulation especially at frequencies above 100 Hz, but for typical practical applications, the effect of this measure is strongly limited to lower frequencies. However, there is a high potential to use the physical effect of modal decoupling to increase the flanking sound insulation especially for constructions of cross-laminated-timber at low and very low frequencies. For this purpose, floors and walls are defined as single subsystems of the overall system of two coupled rooms. These subsystems show local modes, if they are not connected to each other. In contrast, connected subsystems result in global modes of the overall system, if the individual local modes have similar eigenfrequencies. In this case, an excitation of a wall or a floor results in a high vibration response of the coupled wall. The flanking sound insulation especially at low frequencies can be increased, if the generation of these global modes is suppressed. This effect is studied in this contribution using validated numerical models based on the finite element method. Selected constructions have been chosen that are based on panels of cross-laminated-timber. Further, the results of 3D-models of coupled rooms are discussed. These results verify the applicability of this approach for common practical situations, and show the potential to obtain a basic sound insulation at low frequencies by a special design of cross-laminated-timber panels.
Name: Mr Blasius Buchegger