Sets out two laboratory methods for determining the sound power radiated by a device, machine component or subassembly using a laboratory anechoic room having prescribed acoustical characteristics. Applies to sources which produce sound that is uniformly distributed in frequency over the frequency range of interest and is relatively steady for at least 30 s. Applies primarily to small sound sources, i.e. sources whose volumes are preferably less than 0.5 percent of the volume of the test room used for the measurements.