R-21 Cotton Armor insulated wall: 54 STC
R-19 Cotton Armor insulated wall: 53 STC
R-13 Cotton Armor insulated wall: 52 STC
The higher the STC number, the greater the reduction in sound.
(Above STC ratings calculated according to ASTM E-90 testing for sound transmission loss in 24" o.c. steel stud walls and one 5/8th inch layer of type X gypsum on each side.)
For party walls:
R-19 Cotton Armor insulated wall: 59 STC
with two layers of Cotton Armor: 62 STC
R-13 Cotton Armor insulated wall: 57 STC
with two layers of Cotton Armor: 60 STC
(Party wall, STC ratings calculated according to ASTM E-90 testing for sound transmission loss in
double 24” o.c. wood stud walls with one 5/8th inch layer type X gypsum on each side.)