This part of ISO 11546 specifies insitu methods for the determination of the sound insulation performance (insertion loss) of machine enclosures.It applies to a total enclosure only and not to the individual panels from which the enclosure is made.NOTES1 Sound insulation for enclosure panels such as wall elements, doors, windows, silencers, etc should be measured in accordance with other relevant standards.2 Related standards concern noise-attenuation measurements of enclosures under laboratory conditions (ISO 11546-1) and cabins (ISO 11957).The measurement methods specified in this part of ISO 11546 are based on International Standards in the series ISO 3740, ISO 9614 and ISO 11200 (see table 1). Depending on the method chosen, the sound insulation performance (insertion loss) of the enclosure is determined in terms of the reduction of sound power level or sound pressure level. Methods are given for measurements where the enclosure surrounds the actual sound source (machine). When these methods are not practicable, alternative measurements can be performed with an artificial sound source. Such methods are also described in this part of ISO 11546.