A conversion of out-of-plane wave components into in-plane wave components at a junction may lead to increasing values of the flanking sound reduction index. The transformed components may contribute to sound radiation, if a reverse transformation occurs at a second junction during wave propagation. Numerical investigations have been assessed for constructions of cross-laminated-timber to verify this effect and have been compared to equivalent models based on concrete. The results prove the relevance of this effect for typical practical situations.
