The effects of the element damping in sound insulation predictions following EN12354

In the prediction of the sound insulation between dwellings in accordance with EN 12354 the damping of the elements in the actual construction is an important aspect. It should be taken into account through the structural reverberation time or, in case of well-damped and generally light weight elements, it is included in the input parameters. As a simplified approach though, the effect of the damping can be neglected. In this respect several questions are relevant. In what situation should the structural reverberation time in the actual construction be taken into account or when is an element damped enough to make the connections to other elements irrelevant. What relations exists between the junction parameters for damped and reverberant elements? And what errors do we make in neglecting the damping in the actual construction for the elements, for the junctions or for both? Looking deeper into the equations and relations between them some global answers can be given to those questions.