Wave Based Modeling of Structure-Borne Sound Transmission in Finite Sized Double Walls

Invited paper

Arne Dijckmans

KU Leuven

Wednesday 3 june, 2015, 16:20 - 16:40

Auditorium 2 (592)

The sound transmission through double walls is a complex problem which is not fully understood yet. Assumptions made in semi-analytical and statistical models are often not satisfied in laboratory and real conditions. Previously, a wave based model has been developed to model the airborne sound transmission through double walls between two rooms, taking into account the modal behaviour of both rooms and structure. It was shown that the modal behaviour of the double wall can play an important role in a broad frequency range. In this paper, the wave based methodology is extended for the investigation of the sound transmission through double walls with structural connections. The acoustic performance of double leaf walls is often determined by structure-borne transmission through mechanical links between the two leaves, like studs or ties. Point and line connections with an increasing amount of complexity are introduced in the double wall models to incorporate the effect of structure-borne paths. The studs and ties are modeled as rigid connections or a combination of translational and rotational springs. Alternatively, the studs are modeled as beams, accounting for the modal behaviour of the studs. The wave based results are compared with experiments and infinite plate models based on a decoupled approach or a periodic approach. It is shown that the finite dimensions can have a significant influence on the sound insulation, both at low frequencies and at higher frequencies. The pass- and stop-band behaviour of periodic structures cannot fully develop in finite double walls. Furthermore, the studs in double lightweight walls act more as point connections than line connections due to the discrete screw fixings between panels and studs.

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