Impact Insulation Class (IIC) : The method is designed to measure the change in impact sound transmission of a floor-ceiling assembly in a controlled laboratory environment. ASTM E2179-03.

Sound Transmission Class. (STC):The sound-insulating property of a partition element is expressed in terms of the sound transmission loss. (Stand alone product – no ceiling or wall assembly) ASTM E90-04, ASTM E413-04.

Noise Reduction Coefficient (NRC): A single number rating obtained by taking the arithmetic average of the absorption coefficients at specified frequencies, rounded to the nearest 0.05.