Articles tagged “noise criteria”
2 articles covering noise criteria in acoustic engineering and building design.
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TUTORIALS19 min read
NC Curves Explained: Understanding NC-25, NC-35, NC-45 Background Noise Ratings
A comprehensive guide to Noise Criteria (NC) curves: how they work, how to determine an NC rating, target values for every room type, and the differences between NC, NR, and RC rating methods. Includes ASHRAE recommended levels and step-by-step calculation examples.
March 14, 2026
noise criteriaNC curves
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TUTORIALS20 min read
Noise Criteria Explained: NR, NC, and RC Curves — Which One Does Your Project Need?
NR (Noise Rating), NC (Noise Criteria), and RC (Room Criteria) all rate background noise levels in buildings — but they use different curves, different frequency ranges, and are required by different standards. Here is how each system works, when to use which, and the specific values your HVAC engineer needs to hit.
March 14, 2026
noise criteriaNR curve