Cancels and replaces ISO 3743 (1988). Specifies a relatively simple engineering method for determining the sound power levels of small, movable noise sources. In this direct method the A-weighted sound power level of the source under test is determined from a single A-weighted sound pressure level measurement at each microphone position, rather than from a summation of octave-band levels. This method eliminates the need for a reference sound source, but requires the use of a special reverberation test room.