Select acoustical ceiling panels using CAC, NRC, and SAA ratings correctly

Steps

1. Understand CAC (Ceiling Attenuation Class) is tested per ASTM E1414/E1414M, which measures airborne sound attenuation between two rooms sharing a common ceiling plenum — use CAC when the concern is sound transfer between adjacent enclosed spaces (e.g., private offices, exam rooms).
2. Understand NRC and SAA are both derived from ASTM C423 reverberation-room sound-absorption testing; NRC is a single value rounded to the nearest 0.05 based on absorption at defined mid-frequency bands, while SAA is a more granular average across a wider set of one-third-octave bands per C423 — use either when the concern is in-room reverberation/speech intelligibility, not sound transfer between rooms.
3. Recognize a panel can have high sound absorption (NRC/SAA) but low sound blocking (CAC), or vice versa — request both ratings from the manufacturer for the specific product and thickness being specified, since a single 'acoustic rating' does not cover both behaviors.
4. Match the metric to the actual design problem: specify CAC for plenum-shared privacy-sensitive layouts (offices, healthcare); specify NRC/SAA for open-plan reverberation and speech-intelligibility control.
5. Confirm the reported values come from testing on the actual product/assembly (panel plus any backing or accessory) being specified, since these metrics are assembly-specific and not transferable between product lines.