Calibrating Reverberation Room for Accurate Material Sound Absorption Measurements

Comparing material sound absorption test results obtained from pressure decay time measurements from different laboratories is becoming increasingly difficult in the industry. Results often seen in the industry show different material sound absorption coefficient depending on the size and design of the reverberation room, the size of the of the material used in testing, and the type of equipment or method used in acquiring and processing data.

Now that material performance is determined by its ability to meet acoustical specifications set by the customer, usually the Original Equipment Manufacturers (OEMs), there must be a common and best practices that should be followed by suppliers and independent laboratories alike to insure that American Society For Testing and Materials (ASTM) C423 is done correctly.^[1]* This paper addresses factors that affect sound absorption measurements based on a round robin testing of a generic acoustic material that was circulated between laboratories and offers ways to reduce differences in laboratory testing of the ASTM C423 for more accurate results.