This International Standard gives guidance for the use of a series of twelve basic International Standards describing various methods for determining sound power levels from all types of machinery and equipment. It provides guidance on the selection of one or more of these standards which are appropriate to any particular type of sound source, measurement environment and desired accuracy. The guidance given applies only to airborne sound. It is for use in the preparation of noise test codes (see ISO 12001) and also in noise emission testing where no specific noise test code exists. Such standardized noise test codes will recommend the application of the basic International Standard(s) and will give detailed requirements on mounting and operating conditions for a particular family to which the machine under test belongs, in accordance with general principles given in the basic standards. This International Standard is not intended to replace any of the details of, or add any additional requirements to, the individual test methods in the basic standards referred to. NOTE 1 – Two quantities which complement each other can be used to describe the sound emission of machinery and equipment. One is the emission sound pressure level at a specified position and the other is the sound power level. The International Standards which describe the basic methods for determining emission sound pressure levels at the work station and at other specified positions are the series ISO 11200 to ISO 11205. NOTE 2 – The sound energy level mentioned in the ISO 3740 series of standards is not addressed in this guide as it is not mentioned in any legal requirement and therefore not used in practical measurement. Its use is limited to very special cases of impulsive noise sources.