Sound insulation of heavyweight walls with linings and additional layers: numerical investigation

This paper investigates the transfer matrix method to compute the sound transmission loss of heavy- weight building structures with linings or coupled with additional layers to improve acoustic perfor- mances. The simulation of this kind of partitions does not only allow the estimation of the sound insulation given by the element, but it also represents a useful tool to design and optimize wall lin- ings to increase sound insulation. The transfer matrix method is a powerful instrument to examine the sound transmission in multi-layered structures. Thanks to the recent developments presented by different authors, which allow to consider the finite size of the elements and to compute the sound transmission through the structural connections, it is possible to predict results with great accuracy. This method is used in building acoustics mainly to simulate lightweight structures, like double-leaf gypsum board walls. In these cases it is possible to simplify calculations by assuming that the leaves behave as thin plates, and by describing them using a simplified matrix. With heavyweight walls this is not always possible, therefore it is necessary to implement the complete matrix for solid ele- ments. Furthermore, most of these partitions are not homogeneous elements, because they are made in masonry, with concrete or clay bricks and blocks with mortar joints. Hence, it is necessary to de- termine equivalent mechanical parameters to characterize them. The simulated results are compared to the sound transmission loss values of different walls measured in laboratory in order to validate the model.