This part of IEC 60645 specifies a means of describing the physical characteristics of audiometric reference and test signals of short duration and methods for their measurement. [< BR> ]The object of this standard is to ensure that audiometric stimuli of short duration are specified and measured in the same way and that the calibration of equipment using such signals is carried out using defined methods.[< BR> ]This standard does not describe the method of use of short duration test signals.[< BR> ]This second edition cancels and replaces the first edition published in 1994. This edition constitutes a technical revision. Specific changes in this edition concern new figures of reference signals and changes in definitions.