Noise Criteria Curves: NC
NC-25#4000 to NC-30#500
Noise Criteria (NC) and Room Criteria (RC) curves for HVAC acoustics design. NC curves per ANSI S12.2-2008 from NC-15 through NC-70 (12 curves), and RC Mark II curves per ASHRAE from RC-25 through RC-50 (6 curves). Each curve has 8 octave band center frequencies (63-8000 Hz) with maximum allowable sound pressure levels in dB. Includes recommended occupancy type and equivalent dBA background noise level. 144 records total.
| criterion type | curve point | background noise dBA equivalent (dBA) | max sound pressure level dB (dB) | octave band center Hz (Hz) | rating | recommended occupancy |
|---|---|---|---|---|---|---|
| NC | NC-25#4000 | 35 | 22 | 4,000 | NC-25 | hospital |
| NC | NC-25#500 | 35 | 31 | 500 | NC-25 | hospital |
| NC | NC-25#63 | 35 | 54 | 63 | NC-25 | hospital |
| NC | NC-25#8000 | 35 | 21 | 8,000 | NC-25 | hospital |
| NC | NC-30#1000 | 40 | 31 | 1,000 | NC-30 | classroom |
| NC | NC-30#125 | 40 | 48 | 125 | NC-30 | classroom |
| NC | NC-30#2000 | 40 | 29 | 2,000 | NC-30 | classroom |
| NC | NC-30#250 | 40 | 41 | 250 | NC-30 | classroom |
| NC | NC-30#4000 | 40 | 28 | 4,000 | NC-30 | classroom |
| NC | NC-30#500 | 40 | 35 | 500 | NC-30 | classroom |
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