scope:

This standard specifies engineering methods for determining the approximate sound power levels of small noise sources. The measurements are carried out when the source is installed in a specially designed room having a prescribed reverberation time over the frequency range of interest. The results of the measurements are given in terms of either or both A-weighted or octave-band sound power levels of the source.

NOTE: Precision methods for the determination of octave-band and one-third octave-band power levels of small noise sources in reverberation rooms are specified in ANSI S12.31-1990 and S12.32-1990.

The methods of this standard are based on the premise that the sound pressure level, averaged in space and time in the test room, can be used to determine the sound power level emitted by the source. The properties of the test room are chosen so that the room's influence on the sound power output of the source under test is reasonably small. A method is given to determine the number of microphone positions and source locations required in the test room.