NRC Rating Explained

Noise Reduction Coefficient (NRC) is the average sound absorption rating of an acoustic panel measured under ASTM C423 (ASTM International) at four 1/3-octave bands: 250, 500, 1000, and 2000 Hz. NRC values run from 0.00 (fully reflective, like glass) to 1.00 (fully absorptive). OrangePiel printed acoustical panels achieve NRC 0.85 across all standard fabric finishes — meaning they absorb 85 percent of sound energy in the measured band. Custom-printed in Richmond, Virginia since 2006; ASTM E84 Class A fire rating, NFPA 701 compliant, UL GREENGUARD Gold certified.

How NRC is measured

NRC is the average of four sound absorption coefficients — at 250, 500, 1000, and 2000 Hertz — measured per ASTM C423. The test happens in a reverberation chamber at an accredited acoustics lab, not in a manufacturer’s product shoot. A controlled noise source is excited; the chamber’s decay rate is measured both with and without the test panel installed; the difference yields the absorption coefficient at each frequency band. The four results are averaged and rounded to the nearest 0.05.

A panel rated NRC 0.85 absorbs an average of 85 percent of the sound energy that strikes it across the measured band. That 85 percent is not a marketing figure — it is a single number derived from a standardized destructive test that any specifier can replicate at any compliant lab. ASTM C423 is the same standard the Acoustical Society of America references when publishing its acoustical performance criteria.

What NRC values mean in practice

A simple frame for reading NRC values: 0.00 to 0.20 is reflective (concrete, glass, painted gypsum); 0.20 to 0.50 is mildly absorptive (carpet, upholstered furniture); 0.50 to 0.70 is moderately absorptive (acoustic ceiling tile of average grade); 0.70 to 0.90 is absorptive (specifier-grade acoustic panels); and 0.90 to 1.00 is highly absorptive (broadband studio treatment).

OrangePiel printed acoustical panels test at NRC 0.85 in the standard 9 mm thickness. Thicker variants — 25 mm and above — push toward NRC 0.95, which is the broadband absorption profile recording studios specify. The panel’s printed face does not degrade its NRC; the dye-sublimated artwork sits on an acoustically transparent fabric over a sound-absorbing core, so the printed surface and the acoustic surface are the same surface.

NRC vs SAA vs STC — what each metric measures

Three acronyms are commonly conflated in acoustic specifications, and the difference matters when reviewing a 3-part spec. NRC (Noise Reduction Coefficient) and SAA (Sound Absorption Average) both measure absorption per ASTM C423. NRC averages four 1/3-octave bands (250, 500, 1000, 2000 Hz); SAA averages twelve bands (200 to 2500 Hz) and is rounded to the nearest 0.01 instead of 0.05. SAA is the more precise metric and is preferred by LEED v4.1 EQc9 documentation; NRC remains the more widely recognized number in commercial spec sheets.

STC (Sound Transmission Class) is a different measurement entirely. STC measures sound blocking — how much sound an assembly prevents from passing from one room to another — under ASTM E90 and ASTM E413. Acoustic panels do not raise STC. To block sound between rooms, a specifier needs an STC-rated wall assembly (typically STC 50 or higher), not surface-mounted absorption. The most common buyer confusion in this category is asking for "soundproof panels" when the actual requirement is reverberation control, which is what NRC measures.

How much absorption a room actually needs

Acoustic treatment is sized by reverberation time target and wall surface area, not by panel count alone. A speech-priority space (open office, meeting room, classroom) typically targets a reverberation time at or below 0.6 seconds; a music or hospitality space typically targets 0.8 to 1.2 seconds; a recording studio targets 0.3 to 0.5 seconds with broadband absorption.

In practice, that translates to coverage benchmarks: 20 to 35 percent of total wall surface area in speech spaces, 35 to 50 percent in music or restaurant spaces, and 50 to 70 percent in studios paired with diffusers. At NRC 0.85, OrangePiel panels deliver a measurable RT60 reduction below 0.6 seconds in most rooms under 5,000 square feet when sized to the lower end of those ranges. The Joseph and Ulrich (2007) review for the Center for Health Design documented 5 to 15 dBA reductions in healthcare environments using comparable absorption strategies.

What to look for in a spec sheet

A trade-grade acoustic panel spec sheet should make four claims explicit, each anchored to its issuing standard. NRC value per ASTM C423 (the absorption claim). ASTM E84 Class A fire rating with FSI ≤ 25 and SDI ≤ 450 (the IBC Chapter 8 building-code claim). NFPA 701 compliance for the fabric face (the assembly fire claim, required in hospitality and healthcare). UL GREENGUARD Gold certification (the indoor air quality claim, required for school and healthcare purchasing). When a spec sheet leads with adjectives instead of standards, it is not a specifier-grade document.

OrangePiel publishes its NRC test report, ASTM E84 cert, NFPA 701 cert, GREENGUARD Gold cert, AATCC 16.3 colorfastness rating, and CSI 3-part spec on the trade resources page. Each is a third-party document from the issuing body — not a marketing summary.

Where OrangePiel acoustic panels are installed

Custom-printed acoustic panels combining NRC 0.85 absorption with full-bleed dye-sublimated artwork have shipped to corporate offices for Pixar Animation Studios, Yahoo, Workday, Verizon, and the IRS National Headquarters; to hospitality spaces including Hotel Diva (San Francisco) and properties in the Loews Hotels portfolio; and to education installations including the Pennsylvania elementary school cafeteria reference project. Manufactured in Richmond, Virginia since 2006; production runs 2 to 4 weeks from approved proof to ground shipping, free to all 50 states.