Vibration Transmission Across Junctions of Double Walls Using the Wave Approach and Statistical Energy Analysis

The sound insulation between adjacent rooms in buildings is not only determined by direct airborne sound transmission through the common wall, but also by structure–borne flanking transmission. To quantify the flanking transmission, the determination of the vibrational energy transmission at a junction between plates is crucial. In this paper, statistical models are developed for the prediction of flanking transmission across rigid junctions composed of single and double walls. The coupling loss factors are determined from wave theory for semi–infinite plates under the assumption of diffuse vibration fields. In–plane wave transmission must be accounted for in the case of wave transmission across double wall junctions. In general, the vibration transmission across double walls shows similar trends as the vibration transmission across single walls. An initial assessment of flanking transmission across a double wall junction can therefore be made by use of an equivalent single wall junction model. The developed models can also be used to investigate structure-borne flanking transmission across two adjacent single wall junctions. It is shown that indirect coupling between non–adjacent plates is important and should be accounted for in statistical models.