SAA (Sound Absorption Average)

Sound Absorption Average (SAA) is a single-number rating calculated as the average of twelve third-octave band absorption coefficients from 200 Hz to 2500 Hz, rounded to the nearest 0.01. Defined in ASTM C423-17, SAA replaced NRC as the preferred rating in the ASTM system because it uses more data points and finer rounding, providing better discrimination between similar products. SAA and NRC values are typically very close (within 0.05) for most materials, but SAA includes more frequency bands in its calculation. Like NRC, SAA does not capture low-frequency performance below 200 Hz, which is critical for spaces with bass-heavy noise sources. For international projects, the weighted absorption coefficient (αw) per ISO 11654 is used instead. Both SAA and NRC are useful for initial material screening but should be supplemented with full octave-band data for final design decisions.