Evaluation of the flanking transmission in a scale model of two adjoining rooms

Flanking transmission is the sound propagation through the lateral structures of two adjoining rooms. Evaluation of this transmission is possible with a statistical model of the two rooms that consider mainly the reduction in vibration transmission between the partition and the lateral structures. With this model, which is the object of a project of international standard (Pr EN 12354), it is possible to evaluate the transmission through each path, considered independent from each other. The research carried out at the Acoustic Laboratory of the University of Bologna has validated the CEN model measuring the vibration reduction index and the sound transmission in a scale model. The vibration transmission index has been measured both with transient and steady excitation of the structures, the first by mean of an hammer and the second of an electromagnetic shaker. The sound reduction index of each path of transmission has been calculated measuring the mean pressure level in the source room and the mean vibration level of each structure in the receiving room. The paper presents a validation of the model with a comparison between the different kinds of measurement techniques.