BS EN ISO 389-7:2019

This document specifies a reference threshold of hearing for the calibration of audiometric equipment used under the following conditions. The sound field in the absence of the listener consists of either a free progressive plane wave (free field) or a diffuse sound field, as specified in ISO8253-2 . In the case of a free field, the source of sound is directly in front of the listener (frontal incidence). The sound signals are pure (sinusoidal) tones in the case of free-field conditions and one-third-octave bands of (white or pink) noise in the case of diffuse-field conditions. The sound pressure level is measured in the absence of the listener at the position where the centre of the listener’s head would be. Listening is binaural. NOTE1 Correction values for the threshold of hearing under free-field listening conditions and selected angles of sound incidence (45° and 90°) deviating from frontal incidence are given in ISO8253-2 for information. NOTE2 Other conditions are given in Reference [ 1].The data are given in numerical form for the preferred frequencies in the one-third-octave series from 20Hz to 16000Hz inclusive in accordance with ISO266 and, in addition, for some intermediate audiometric frequencies up to 18000Hz.The threshold data differ from the audiometric zero specified in ISO389-1, ISO389-2, ISO389-5 and ISO389-8, since the latter refer to monaural listening through earphones with sound pressure levels referred to specified couplers and ear simulators. Direct comparison between the data in the parts of ISO389 mentioned above and in this document is therefore not appropriate.