ISO 3381:2005

ISO 3381:2005 specifies the conditions for obtaining reproducible and comparable measurement results of levels and spectra of noise inside all kinds of vehicles on rails or other types of fixed track, except for track maintenance vehicles in operation.
It is applicable to type testing and periodic monitoring testing.
The results may be used, for example, to characterize the noise inside these vehicles and to compare the internal noise of various vehicles on a particular track section.
The test procedures specified in this ISO 3381:2005 are of engineering grade (grade 2, with a precision of 2 dB), that is the preferred one for noise declaration purposes, as defined in ISO 12001.