This International Standard specifies a laboratory method (clause 6) and in situ methods (clause 7) for the determination of the sound insulation performance of sound-protecting cabins. The sound insulation performance is the reduction in sound pressure level or sound power level afforded by the cabin. The methods are applicable to cabins with a small leak ratio (e s 2 %). This International Standard is applicable to a complete cabin only and not to the individual components from which it is made. NOTE 1 – Sound insulations for cabin components such as wall elements, doors, windows, silencers, etc. should be measured according to other relevant standards. Requirements for the test environment in the laboratory are based on those given in IS0 3741.