声学 - 用于校准听力设备的参考零 - 第7部分:自由场和扩散场聆听条件下听力的参考阈值

[中文适用范围]： 本文件规定了在以下条件下使用的听力测量设备校准的参考听力阈值。 a) 听者不在场时的声场由自由渐进平面波（自由场）或扩散声场组成，如 ISO 8253-2 中所规定。 在自由场的情况下，声源位于听者的正前方（正面入射）。 b) 在自由场条件下，声音信号是纯（正弦）音调；在扩散场条件下，声音信号是三分之一倍频程（白色或粉色）噪声。 c) 声压级是在听者不在场的情况下在听者头部中心位置测量的。 d) 聆听是双耳的。 注 1：ISO 8253-2 中给出了自由场听音条件下的听力阈值和偏离正面入射的选定声音入射角度（45° 和 90°）的校正值，以供参考。 注2：其他条件在参考文献[1]中给出。 根据 ISO 266，数据以数字形式给出，适用于从 20 Hz 到 16000 Hz（含）的三分之一倍频程系列中的首选频率，此外，还针对高达 18000 Hz 的一些中间听力频率。 阈值数据与 ISO 389-1、ISO 389-2、ISO 389-5 中指定的听力测定零值不同，并参考指定的耦合器和耳朵模拟器。 各部分数据直接比较 [外文原描述]： This document 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, as specified in ISO 8253‑2. In the case of a free field, 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. NOTE 1 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 ISO 8253-2 for information. NOTE 2 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 20 Hz to 16 000 Hz inclusive in accordance with ISO 266 and, in addition, for some intermediate audiometric frequencies up to 18 000 Hz. The threshold data differ from the audiometric zero specified in ISO 389‑1, ISO 389‑2, ISO 389‑5 and ISO 389‑8, 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 ISO 389 mentioned above and in this document is therefore not appropriate.