4.1 Acoustically absorptive materials are used for the control of reverberation and echoes in rooms. This standard provides a classification method for acoustically absorptive materials applied directly to surfaces by trowel or by spray.

1.1 This classification covers materials applied by trowel or spray to surfaces for the purpose of increasing their acoustical absorption.

1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.