The ABC's of Noise Control

Sound Absorbers are soft, porous, open-celled materials such as foam sheets or fibre blankets and baffles that reduce the reflection of sound waves.  Their sound absorption efficiency is rated by an NRC number - Noise Reduction Coefficient.  The higher the NCR rating, the more efficient the product is at absorbing.

Noise Barriers combine mass, flexibility, and limpness to block noise from transmitting from one area to another.  Flexible mass-loaded vinyl sheeting has replaced thin lead sheets as the noise barrier of choice.  Noise barriers are rated by an STC number - Sound Transmission Classification.  The higher the STC rating, the more efficient the product is at blocking noise.

Acoustical Composites are products that combine both noise barrier and absorber materials.  Typically, they offer the most significant overall noise reduction.  Acoustical composites are rated in both NRC and STC numbers.