Specifies methods for determining sound power level or sound energy level of a noise source by comparing measured sound pressure levels emitted by a source (machinery or equipment) mounted in a hard-walled test room, characteristics of which are specified, with those from a calibrated reference sound source. Sound power level (or in the case of noise bursts or transient noise emission, sound energy level) produced by a noise source in freq bands of width 1 octave is calculated using those msmts.