stc rating operable walls acoustic STC RATING AND NOISE REDUCTION Skyfold offers superior sound separation capabilities with an STC rating of 51. Perhaps more important is the "real world" performance of its operable walls. It is typically superior than other conventional operable wall systems of equivalent STC ratings. ’s sound separation capabilities do not deteriorate over the life of the wall. A normal Skyfold partition has a thickness of 260 mm with two independent planes of steel panels separated by an 146 mm air space that creates an anechoic chamber. Acoustic test results as conducted by the NRC in Ottawa are available upon request.