STC (Sound Transmission Class) ratings establish a way to average how much sound is stopped by something. STC ratings are used for windows, doors, walls and most building materials. STC ratings are the only way to accurately compare various noise reduction products. An STC rating is an instrument measurement of how much noise is stopped.

Sound transmission can cause noise control, confidentiality, and privacy issues. Sound from noises scubas airplanes, traffic or subway trains can transmit through a partition into a quieter space. If sound transmission is not properly controlled, the space or environment will not provide privacy for its users.