Flanking transmission in CLT building elements: Effect of mounting conditions on sound reduction index

One of the main limitations of the laboratory measures of sound reduction index of building elements according to the standards of the ISO 10140 series is the difficulty to make "non-flat" samples in the test opening to simulate the actual "T" or "X" connections, typical of separating building structures, in order to test simultaneously both sound and vibration reduction indexes. Due to the particular dimensional and geometric characteristics of the Acoustic Laboratory (LabAcus) at University of Padova, a special setup was arranged in the opening between the two adjacent reverberation rooms for the measurement of sound insulation. A T-junction was made applying a vertical CLT element to a full size CLT vertical wall installed in the test opening. Measurements of sound reduction index and vibration reduction index were carried out at the same time on the same sample, changing the mounting conditions (interposition of an elastic interlayer, variation in type and number of fixing elements, etc.)