Ceiling Attenuation Class (CAC): CAC indicates a suspended acoustic ceiling’s ability to block sound traveling through a plenum when the wall does not extend full height. High CAC values indicate higher levels of sound insulation between rooms. Suspended acoustic ceilings typically have CAC ratings between 20 and 35.Click to see full answer. Besides, what is a good noise reduction coefficient?The Noise Reduction Coefficient (commonly abbreviated NRC) is a single number value ranging from 0.0-1.0 that describes the average sound absorption performance of a material. This is more conceptual than physically achievable: even very thick concrete walls will attenuate sound and may have an NRC of 0.05.Also Know, is a higher or lower STC rating better? Higher STC ratings generally are better. This means that extremely low frequencies don’t register on the STC rating scale, thus when a sound on one side of a wall is below 125Hz, the ability of the wall to block sound cannot be calculated. STC is not a direct measure of how many decibels of sound a wall can stop. Similarly one may ask, what is NRC in ceiling tiles? High-NRC Ceiling Tiles. NRC, or Noise Reduction Coefficient, is a measure for rating the overall sound absorption of a material installed inside a building where sound is reflected at many angles of incidence.Do acoustic ceiling tiles absorb sound?Soundproofing isn’t just for walls. Our acoustic ceiling tiles can go right into an existing T-bar suspended grid system. We have a large variety of acoustical ceiling tiles for sound control and noise reduction. Ceiling tiles may absorb sound, block sound or scatter sound.