This Standard specifies methods determining the sound power level or sound energy level of a noise source from sound pressure levels measured on a surface enveloping a noise source (machinery or equipment) in a test environment for which requirements are given. The sound power level (or, in the case of noise bursts or transient noise emission, the sound energy level) produced by the noise source with frequency-weighting A applied is calculated using those measurements. The methods specified in this Standard are suitable for all types of noise (steady, non-steady, fluctuating, isolated bursts of sound energy, etc.) defined in DIN EN ISO 12001. This Standard is applicable to all types and sizes of noise source (e. g. stationary or slowly moving plant, installation, machine, component or sub-assembly), provided the conditions for the measurements can be met. The test environments that are applicable for measurements made in accordance with this Standard can be located indoors or outdoors, with one or more sound-reflecting planes present on or near which the noise source under test is mounted. Information is given on the uncertainty of the sound power levels and sound energy levels determined in accordance with this Standard, for measurements made with frequency weighting A applied. The uncertainty conforms with that of accuracy grade 3 according to DIN EN ISO 12001.