Composite Acoustic Barriers
Acoustic barriers are generally made from panels of different acoustic performance.
A single layer barrier between 2 rooms that is made up of 2 different materials.
If a partition is made up from different areas with different transmission loss performances the total transmission loss for the partition may be calculated given the following formula:
Where
Si = area of ith panel in barrier [m2]
Ri = transmission loss of ith panel in barrier [dB]
Stot = total area of the barrier [m2]
When the panels are the same area the transmission loss of the panel with the lowest transmission loss controls the overall performance of the partition.
Panel 1 and Panel 2 equal in area.
Panel 2 is 10% of the total area.
The above graph shows the transmission loss of two panels and the combined transmission loss. The area of Panel 2 is 10% of the total area. From this it can be seen that the transmission loss of the weaker area dominates, even when it is a small percentage of the total area.
From this it can be seen that when developing the transmission loss performance of a partition it is important to understand the complete system and if possible to improve the weakest areas first.
See also: Double Acoustic Barrier, Holes in Acoustic Barriers, Single Acoustic Barrier.
Subjects: Noise & Vibration