Ceiling Attenuation Class (CAC)
What is CAC? Ceiling Attenuation Class is a measure for rating the efficiency of a ceiling system as a barrier to airborne sound transmission between adjacent closed spaces that share a common air plenum. The higher the CAC rating, the better the performance. A ceiling system with a CAC less than 25 is very low performance, whereas a ceiling with a CAC of 35 or greater is considered high performance.
Absorption is not a substitution for blocking
Ceilings with high NRC only can absorb sound within the space – but cannot block sound from leaving or entering the space. Ceilings with a CAC of 35+ will help block sound from traveling to adjacent spaces through the plenum, providing improved sound isolation, speech privacy, and design flexibility.