noise criterion curves

NC curves

A series of curves of octave-band sound spectra, used to provide a single-number rating of the noisiness of an indoor space. A measured octave-band spectrum is compared with this set of curves to determine the NC level of the space in which the measurements were made.
References in periodicals archive ?
Then, for each octave band a room reverberation correction and a standard room correction of minus 10 dB, to convert from sound pressure to sound power, were applied to the noise criterion curves to obtain the noise criteria level (NC) for the sound generated by the discharge (ASHRAE 2009).
The noise criterion curves produced by Beranek specify maximum sound levels permitted in each octave band for a specific NC curve (Reynolds 1997).