Godinho L., Tadeu A., Santos A.

In this work, the authors present experimental results for the airborne sound insulation of layered walls. For this purpose, two series of test specimens have been analyzed in the laboratory. The first consists of plasterboard panels, separated by an air gap which can either be empty, partially filled with rockwool or partially filled with cork panels. The second consists of a traditional brick wall reinforced with plasterboard panels, attached to different absorbing materials. All lab results are obtained according to ISO 140-3:1995. The experimental results are compared to those provided by the mass law and to those computed using theoretical calculations performed using analytical solutions that allow the assessment of airborne sound insulation provided by multi-layer systems. The latter model uses fundamental solutions obtained in the frequency domain for the case of general multi layer structures, built as a sequence of fluid and solid layers, being an extension of the expressions derived previously by the authors for the prediction of airborne sound insulation of single and double panels, excited by 1D, 2D or 3D sources. The interaction between the solid and the fluid layers is fully taken into account, and internal loss factors are considered.