# Noise Reduction Coefficient

Arithmetic mean of sound absorption coefficients at 250, 500, 1000, and 2000 Hz, rounded to the nearest 0.05 metric sabin per square metre.

- NRC < 0.50 is a poor absorber
- NRC > 0.80 is a very good absorber

This gives a measure for rating the overall sound absorption performance of a material when used in an enclosed architectural space, where sound is being reflected at many angles of incidence.

**See also: **Absorption Coefficient.

**Subjects: ** Noise & Vibration