On the air-borne sound insulation of double wall constructions: Fid-Bau Portal

On the air-borne sound insulation of double wall constructions

Kropp, W. / Rebillard, E.

The paper focuses on the possibilities to optimise the sound insulation of double wall constructions at low frequencies. The expression low frequencies implies a frequency range where the fundamental resonance frequencies of double wall constructions or the critical frequency of stiff single leaves (e.g. concrete walls) are normally situated. Both effects lead to a reduced sound insulation which can cause problems to fulfil requirements. Three different cases are distinguished. Firstly, the case where the double wall resonance frequency is much higher than the critical frequency of the total construction. The double wall is then well coupled and can be considered as one plate. Secondly, the opposite case where the double wall resonance frequency is much lower than the critical frequency of the individual panels. In this case the panels will act independently. The third case is when both double wall resonance and critical frequencies are close to each other. An analytical model is used to study the potential for optimisation for these three cases. This model does not include radiation loading, however the results are verified by a complete model also including radiation loading.