Sound transmission loss analysis through a multilayer lightweight concrete hollow brick wall by FEM and experimental validation

This research work tries to find the most efficient numerical procedure to predict the transmission loss (TL) through a multilayer wall for frequencies ranging from 100 to 5000 Hz. The wall is made of lightweight concrete hollow bricks joined by mortar, with gypsum lining on both faces. This study is motivated by the need to develop new products with better acoustic properties of airborne sound insulation. In order to achieve this objective a set of tests using source and receiving chambers have been modelled according to the basic requirements of the UNE-EN ISO 140-1 standard rule. The constructive element is located between both chambers in order to evaluate its acoustic behaviour according to the UNE-EN ISO 717-1 standard rule. Applying the finite element method (FEM), a two-dimensional model with fluid-structure interaction has been built in the case of the horizontal and vertical planes, with the purpose of including the different eigenfrequencies of the rooms. The values of the average sound pressure in both test chambers have been calculated for different excitation sources: uni and omnidirectional waves. The convergence and accuracy of the proposed method are then assessed by comparing FEM results with experimental measurements carried out by a certified laboratory. Finally, the numerical procedure implemented in this work may be useful to evaluate the acoustic behaviour for other structural building elements and reduce the manufacturing time to develop new products in construction.