1.1 General This international Standard specifies a method for measuring the sound pressure levels on a measurement surface enveloping the source in order to calculate the sound power level produced by the niose source. It gives requirements for the test environment and instrumentation as well as techniques for obtaining the surface sound pressure level from which the sound power level of the source is calculated, leading to results which have a grade 3 accuracy.It is important that specific noise test codes for various types of equipment be established and used in accordance with this international Standard. For each type of equipment, such niose test codes will give detailed requirements on mounting, loading and operating conditions for the equipment under test as well as a selection of the measurement surface and the microphone array as specified in this International Standard.NOTE 1 The noise test code for a particular type of equipment should give detailed information on the particular surface that is selected, as the use of differently shaped measurement surfaces may yield differing estimates of the sound power level of a source.1.2 Types of noise and noise sourcesThe method specified in this International Standard is suitable for measurements of all types of noise. NOTE 2 A classification of different types of niose (steady, non.steady, quasi.steady, impulsive, etc.) is given in ISO 12001.This International Standard is applicable to noise sources of any type av size (e.g. device, machine, component, sub-assembly).NOTE 3 Measurements according to this International Standard may be impracticable for very tall or very long sources such as chimneys, ducts, conveyors and multisource industrial plants.