What does NRC stand for and what does it quantify in interior acoustics?

• A. Noise Reduction Coefficient; it quantifies the average sound absorption of a material across frequencies.
• B. Noise Reduction Coefficient; it measures the colorfastness.
• C. Noise Reduction Constant; it estimates heat transfer.
• D. Noise Reduction Characteristic; it rates fire performance.

Answer: (A)

NRC stands for Noise Reduction Coefficient, and it quantifies the average sound absorption of a material across a range of mid-frequency bands relevant to rooms. Specifically, it’s calculated as the average of absorption coefficients at 250, 500, 1000, and 2000 Hz, yielding a value from 0 to 1 where higher numbers indicate more absorption. This helps predict how a material will affect reverberation and speech intelligibility in interior spaces. It isn’t about colorfastness, heat transfer, or fire performance, which is why the other options don’t fit.