Modelling of impervious layers from measurements of the sound reduction index

In this work, developed algorithms are described to characterise impervious layers. It also includes measurements for their sound reduction indexes. These algorithms are based on the minimisation of the quadratic error and allow determining the parameters that characterise the impervious layer. To improve characterization, there is a revision of the classic model of impervious layer in matters of the bending stiffness, and different corrections on the total loss factor of the layer are introduced. This permits the to adjust with greater precision the prediction of the critical frequency. The use of this method is defensible considering that there are many ways of measuring the insulation of impervious layers and, through this particular method, they can be used to obtain the values for the mechanical characteristics of the layer, with the appropriate laboratory set-up conditions. Then, those values can be used in simulation algorithms for multiple layer partitions, obtaining predictions, which contain, implicitly, the set-up condition of each impervious layer.