How can you have a Sound Absorption Coefficient of greater than 1.00 e.g. 6″ Type IV Acousta-Wal® shows a coefficient of 1.23 at 500 Hz.?
This is an anomaly that occurs when the resonant frequency of the Acousta-Wal® block cavities occur at or near the test frequencies. The standard used in ASTM C423 is that 100% of sound is absorbed by an open window (and the test equipment is calibrated accordingly). ASTM also requires that the readings shown on the test instruments be recorded exactly — even though common sense dictates that more than 100% of any sound cannot be absorbed.
