Sound absorption is a measure of the sound energy that is not reflected back when it reaches a surface. Sound absorption is generally expressed as a single number rating, the Noise Reduction Coefficient (NRC) of the building material. Industry test standards ASTM C423 and ISO 354 are common methods for measuring the sound absorption of a building element.
Sound absorption is measured by placing the building element in a reverberation chamber, then a sound source introduces broadband noise into the chamber. The highly reflective walls in the room create a diffuse field, meaning the source doesn’t seem to come from any specific location. The reverberation time is measured in the room with and without the sample. By comparing these, the amount of sound that was absorbed by the sample can be calculated.
The staff at VIacoustics are intimately familiar with these tests. We can help you build your chambers from the ground up, outfit your existing chambers with instrumentation and software, and train you to use all of it.