Q:  What is NRC?

NRC means Noise Reduction Coefficient.

It is the average sound absorption coefficient measured at four frequencies: 250, 500, 1,000, and 2,000 Hz expressed to the nearest integral multiple of 0.05. It is measured in accordance with ASTM C423 and rates the ability of a ceiling, wall panel, or other material to absorb sound.

The NRC is averaged over all angles and sound frequencies, and represents the average absorption per unit area. The NRC ranges from 0.00 (concrete floor) to 1.00 (high performance acoustical products like OPTIMA).