Sound Transmission Classification (STC)
8” Dense concrete block wall, 2 coats of paint each side” STC-52 4” Face brick, mortared together: STC-36 ½” Gypsum board (both sides) to 35/8” metal studs: STC-36 Acoust-A-Pane CitiQuiet interior window: STC-38 ½” Laminated CitiQuiet interior window: STC:-38 ½” CitiQuiet interior window: STC:-36 ¼” Laminated CitiQuiet interior window: STC:-35 ¼” CitiQuiet interior window: STC:-31 1/8” CitiQuiet interior window: STC:-29 3/32” Standard wood frame window: STC-13 3/32” Standard steel casement window: STC-13	Determining Sound Transmission Class. To provide a single number rating for describing the sound isolation Performance of a material, the American Society for Testing and Materials has developed the sound transmission class, or STC, rating. STC is a single number rating derived from individual transmission losses at specified test frequencies (ASTM E-90; ASTM E-413;). It allows a preliminary comparison of the performance of various glazing materials. Final glazing selection should be based on a comparison of TL performance at all frequencies of the actual sound spectrum to be controlled.
Acoustical Performance of Glass Fabrications   Overall Thickness Inside Outside STC Value   Laminated Glass Laminated Insulated Glass Double Laminated Insulated Glass Non Lami Insulated Glass Monolithic Glass 1/4" 3/8” 1/2" 5/8” 3/4” 1” 11/8” 17/16” 1” 13/4” 1/2" 1” 11/2” 1/4" 1/2" 1/8” 1/4" 1/4" 3/8” 1/2" 1/4" Lami 3/8” Lami 1/4" Lami 1/4" Lami 1/2" Lami 1/8” 1/4" 1/4" 1/4" 1/2" 1/8” 1/8” 1/4" 1/4" 1/4" 1/4" 1/4" 3/16” 1/4" Lami 5/16” Lami 1/8” 1/4" 1/4" 35 36 38 40 41 39 40 42 42 46 28 35 37 31 36 .5 Airspace .5 Airspace 1 Airspace .5 Airspace 1 Airspace .25 Airspace .5 Airspace 1 Airspace The American Society For Testing and Materials (ASTM) The Hiher the Sound Transmission Classification (STC) values, the Greater the Noise Reduction.