Transmission Loss of Partition Walls

Results of the measurement on sound insulation of a few partition walls are presented. The sound insulation has been measured in the transmission-reverberation chamber of this Institute. The results are compared with theoretical predictions. A simplified method is adopted to obtain approximate theoretical values of the transmission loss (T.L.).Three types of partition walls, a solid brick wall, brick cavity wall and a double wall plywood panel have been tested. The experimental values of transmission loss of the brick cavity wall is found to be lower than the computed values. This is due to sound transmission through the wire-ties bridging the two panels. The transmission loss of a single thin panel of plywood is too low to meet the insulation requirements. Sound insulation of such panels can be increased by using two panels with a little air space in between. An absorbent material loosely filled in the cavity further improves the transmission loss.