In practice, there is a strong link between sound absorption and
room-to-room sound insulation. This link may not be accurately
refl ected in laboratory testing. In practice, two ceilings with the
same ceiling attenuation class (CAC), but different NRCs, produce
different levels of perceived sound insulation. The ceiling with the
highest NRC will do a better job of lowering the sound pressure in
both the sending and the receiving room.
