chapter  9
28 Pages

Airborne sound transmission through double constructions

ByJens Holger Rindel

This chapter describes the theoretical basis of sound insulation of double constructions. The difficulties in calculating the sound insulation of double constructions are especially related to mechanical connections including boundary connections. If the boundary conditions of a plate are neglected, a plane sound wave at normal incidence will not create bending waves in the plate, but the plate will move with all parts in phase. A double construction can consist of two parallel plates separated by a cavity which contains an elastic material with the density ρd, and the speed of sound. The sound transmission will be partly through the cavity and partly via possible mechanical connections, the so-called sound bridges. The latter is dealt with in the chapter. If the boundary conditions of a plate are neglected, a plane sound wave at normal incidence will not create bending waves in the plate, but the plate will move with all parts in phase.