DIN EN ISO 389-7:2017-01

In some audiological applications, the test signals are generated in the free or diffuse sound field with the aid of loudspeakers. This part of DIN EN ISO 389 specifies the reference zero for the calibration of audiometric equipment used for sound field audiometry. The associated audiometric test methods are specified in DIN EN ISO 8253-1 and DIN EN ISO 8253-2. Like other subjective phenomena, the hearing threshold varies from person to person. However, for a group of otologically normal persons in a limited age range, values can be determined that describe the average behavior of the group. This and other parts of DIN EN ISO 389 specify hearing threshold data that apply to otologically normal persons in the age range from 18 to 25 years. This part of ISO 389 specifies a reference threshold of hearing for the calibration of audiometric equipment used under the following conditions: a) The sound field in the absence of the listener consists of either a free progressive plane wave (free field) or a diffuse sound field. In the case of a free field the specifications in ISO 8253-2 shall apply and the source of sound is directly in front of the listener (frontal incidence). b) 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. c) 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. d) Listening is binaural. The standard differs from DIN EN ISO 389-7:2006-04 as follows: a) adaptation of values in Table 1; b) additions to Clause A.1, Free-field conditions; c) addition of Table A.2, Investigations of hearing thresholds to derive the threshold values at 20 Hz and 18 000 Hz; d) adaptation of the bibliography. The responsible committee is DKE/GUK 821.6 "Hörgeräte und audiometrische Messtechnik" ("Hearing aids and audiometric measurements") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.