Acoustic Ceilings: Noise Reduction Coefficient (NRC)

Acoustic Ceilings: NRC
Recommended products:


High Acoustics NRC measures the average percentage of noise a material absorbs at four frequencies: 250, 500, 1000, 2000Hz.  This key measure of absorption of general office noise is expressed as a single value percentage from 0.0 to 1.0 (Reference: AS 1045-1989, ASTM C 423-00 and E 795-00).

Superior acoustical performance ICON indicates Armstrong products with:


For more information, see:  Improve Workspace Effectiveness: With UL Classified High Performance Acoustical Ceilings.


Acoustic Ceilings: Ceiling Attenuation Class (CAC)

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CAC rates a ceiling structure’s efficiency as a barrier to airborne sound intrusion between two closed rooms, over the speech frequency range.

It is an especially significant measure in providing acoustic privacy between adjacent work areas, where sound can penetrate plenum spaces and carry to other spaces.

CAC is stated as a minimum value; CAC minimum 25 is acceptable in open plan offices, while a rating of minimum 35 or 40 is preferred for closed offices. (Reference: AS 2499:2000, ASTM E 1414-00a )

For more information, see:  Improve Workspace Effectiveness: With UL Classified High Performance Acoustical Ceilings.



Acoustic Ceilings: Articulation Class (AC)

Acoustic Ceilings: AC

Recommended products:
Optima Open Plan:  AC=200



High Acoustics AC rates a ceiling’s suitability for achieving normal speech privacy in open office spaces by absorbing noise reflected at an angle off the ceiling into adjacent cubicles. 

This is a measure of the noise reflected over office partitions (60", 1.5M high) in the frequencies critical to speech intelligibility and conversational privacy. 

AC is the primary measure of acoustic performance in the open plan.  (Reference: AS 1045-1989, ASTM C 423-00 and E 795-00 )

For more information, see:  Improve Workspace Effectiveness: With UL Classified High Performance Acoustical Ceilings.

Superior acoustical performance ICON indicates Armstrong products with: