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Published 2026-02-18 · 6 min read

Noise Reduction Coefficient (NRC) Explained Simply

The most important number on a ceiling tile spec sheet, in plain English.

NRC shows up on every acoustical ceiling tile and wall panel data sheet. It's the single most important performance number for sound absorption. But what does it actually mean, and what numbers should you look for? Here's the no-jargon version.

What NRC Means

NRC stands for Noise Reduction Coefficient. It measures how much sound a material absorbs versus reflects. The scale runs from 0.00 to 1.00 (and sometimes slightly above 1.00 due to testing methods).

  • NRC 0.00 = perfectly reflective. All sound bounces back. (Think: glass, concrete)
  • NRC 1.00 = perfectly absorptive. All sound is absorbed. (Nothing is truly 1.00, but good acoustic products get close)

So a ceiling tile with NRC 0.55 absorbs about 55% of the sound energy that hits it and reflects the other 45% back into the room. A tile with NRC 0.85 absorbs 85% and reflects only 15%.

How NRC Is Measured

NRC is tested in a lab per ASTM C423. They put a sample of the material in a reverberant chamber — a hard-walled room designed to bounce sound around — and measure how much the material reduces the reverberation. The test measures absorption at four specific frequencies: 250 Hz, 500 Hz, 1000 Hz, and 2000 Hz, then averages them.

Those four frequencies roughly cover the speech range — the sounds that matter most in offices, classrooms, and healthcare spaces. That's why NRC is useful for these environments.

NRC Ranges for Ceiling Tiles

  • NRC 0.50–0.55: Basic/budget tiles. Armstrong 769, USG Radar 2310. Fine for utility spaces, storage, back-of-house.
  • NRC 0.55–0.65: Standard commercial. Good for general office and retail.
  • NRC 0.65–0.75: High-performance. Armstrong Ultima, CertainTeed Symphony. Good for open offices, classrooms, conference rooms.
  • NRC 0.75–0.95: Premium acoustic. Healthcare, recording studios, spaces where noise control is critical.

NRC vs CAC: Two Different Things

NRC measures absorption — how much sound the tile soaks up to reduce noise within the room. CAC (Ceiling Attenuation Class) measures how well the tile blocks sound from passing through to the next room via the shared plenum.

You need high NRC to make a room quieter. You need high CAC for privacy between rooms. They're different properties, and a tile can be high in one and low in the other. Read our full NRC and CAC guide for the detailed breakdown.

What NRC Should You Specify?

Here's a practical guide by space type:

  • Open offices: NRC 0.70 minimum, 0.80+ preferred
  • Private offices: NRC 0.55–0.70 (walls do most of the work)
  • Classrooms: NRC 0.70 minimum per ANSI S12.60
  • Healthcare: NRC 0.70–0.90 depending on the space
  • Corridors and lobbies: NRC 0.55–0.65
  • Conference rooms: NRC 0.65–0.80
  • Restaurants: NRC 0.70+ (hard surfaces everywhere else make ceilings critical)

Common Misconceptions

"Higher NRC is always better." Not necessarily. In some spaces, too much absorption makes the room feel "dead" — no natural reverberation, which feels unnatural. Concert halls and some worship spaces intentionally use lower NRC to maintain liveliness. For commercial offices and classrooms, though, more absorption is almost always better.

"NRC 0.55 and NRC 0.75 — that's only a 0.20 difference." True on paper. In practice, going from 0.55 to 0.75 is a noticeable improvement that everyone in the room will comment on. It's not linear — the first 0.20 increase from nothing feels smaller than the next 0.20 in the middle of the range.

Bottom Line

NRC tells you how much sound a ceiling tile absorbs. Higher number = more absorption = quieter room. For most commercial spaces, aim for NRC 0.65 or higher. Skip the budget tiles in spaces where people work, learn, or heal — the cost difference is small compared to the acoustic improvement.

Need help choosing tiles for your project? Check our ceiling tile buying guide or contact us for product recommendations.