ABSTRACT
The sound insulation of single constructions is rather complicated. One reason for this is that two transmission mechanisms, the forced and the resonant, are in play at the same time. The mass law expresses the airborne sound insulation of a plate in dependency of its mass per unit area. The aim of this chapter is to describe the physical principles of sound transmission and derive a general formula for the transmission loss that covers the range from thin to thick panels and includes effects due to the finite area of the panels. The forced transmission is analysed in some detail and combined with the results from SEA in order to establish more general models for the total transmission. Examples of measured loss factors are shown. At the lower frequencies, the sound transmission of thick plates is dominated by single structural modes.
