IEC 60268-16:20 20定义了STI模型、测试信号、测量和预测方法。 本文件的目的是为音频、通信和声学领域的STI模型的所有类型的用户提供一个全面的手册。 本文件没有提供传输信道认证的STI标准（例如语音报警系统的标准），但附录G提供了一些典型的应用值。 每种测量方法都有局限性，读者可以参考与局限性相关的条款，例如语音隐私、回声和使用数字语音压缩（声码器）的系统。 尽管7.13和8.9.3中提供了一些关于处理这一复杂问题的一般性意见，但本文件不包括STI上波动噪声的情况。 IEC 60268-16:20 20取消并取代了2011年发布的第四版。本版构成技术修订版。 与上一版相比，此版本包括以下重大技术变更: a)男性语音测试信号的频谱已经改变，其中在125Hz和250Hz频带中实现显著减小； b)对公式进行了一些修正； c)包括有关预测和测量程序的附加信息； d)女性语音的频谱和加权因子已被去除； e)添加的STI测量装置的验证信息； f)附件E中更新了STI与其他语音清晰度测量数量之间的关系； g)附录M中提供了更多关于调整测量的STI结果以模拟替代环境噪声和语音水平的影响的信息。

IEC 60268-16:2020 defines the STI model, test signals, measurement and prediction methods.
The objective of this document is to provide a comprehensive manual for all types of users of the STI model in the fields of audio, communications and acoustics.
This document does not provide STI criteria for certification of transmission channels (e.g. criteria for a voice-alarm system), but some typical application values are provided in Annex G.
Every measurement method has limitations, and the reader is referred to clauses relating to limitations such as speech privacy, echo and systems using digital voice compression (vocoders).
This document does not cover the case of fluctuating noise on the STI, although some general comments on dealing with this complex issue are provided in 7.13 and 8.9.3.
IEC 60268-16:2020 cancels and replaces the fourth edition published in 2011. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) the spectrum of the male speech test signal has been changed, with significant reductions in the 125 Hz and 250 Hz bands being implemented;
b) some corrections to formulae have been made;
c) additional information has been included on prediction and measurement procedures;
d) spectrum and weighting factors for female speech have been removed;
e) verification information for STI measurement devices added;
f) the relationships between STI and number of other speech intelligibility measures have been updated in Annex E;
g) greater information is given in Annex M about adjustments to the measured STI results to simulate effects of alternative ambient noise and speech levels.