How Noise Barriers Work

Use: to block transmission noise
Physical Properties: Barriers are non-porous, high density and usually non-fibrous. Barriers are generally flexible or damped. The noise is blocked, reflected and re-routed in another direction.
Barrier materials are tested and rated for their Sound Transmission Loss capability. The number is stated in dB and the higher number signifies the better barrier.
Effectiveness is expressed as STC (Sound Transmission Class).
STC is the single number rating derived from decibel loss data at several frequencies.

Sound Transmission Class of Materials

Material STC
1 lb. density barrier material 26
1 lb. density transparent curtain 26
5/8" gypsum wallboard 30
3/16" steel wall 31
2" fiberglass curtain with 1 lb. barrier 29
2" thick metal panel (solid and perforated) 35
4" thick metal panel (solid and perforated) 41
12" thick concrete 53
3/8" plasterboard 26
22 gauge steel 25
Solid core wood door, closed 27
Concrete block wall, unpainted 44