Reference zero for the calibration of audiometric equipment - Part 1: Reference equivalent treshold sound pressure levels for pure tones and supra-aural earphones (ISO 389-1:1998); English version of DIN EN ISO 389-1— 10 стр.
Sound system equipment - Part 16: Objective rating of speech intelligibility by speech transmission index (IEC 60268-16:2011); German version EN 60268-16:2011— 74 стр.