IEC 60118-4:20 14+A1:2017适用于产生音频交变磁场的音频感应回路系统，旨在为使用感应拾取线圈（拾音线圈）操作的助听器提供输入信号。在整个本标准中，假定与本标准一起使用的助听器符合IEC 60118的所有相关部分。本标准规定了用于助听器目的的音频感应回路中的场强要求，这将提供足够的信噪比，而不会使助听器过载。该标准还规定了可接受的清晰度的最低频率响应要求。规定了测量磁场强度的方法，并给出了有关适当测量设备的信息（见附件B）、应向系统操作员和用户提供的信息（见附件C）以及其他重要考虑因素。本标准没有规定IEC 62489-1中涉及的环路驱动器放大器或相关麦克风或音频信号源的要求，也没有规定ITU-T P.370范围内的设备（如电话听筒）产生的场强的要求。这第三版取消并取代了2006年出版的第二版。本版本是一个技术修订版，包括与上一版本相比的以下重大技术变化:增加了附件G、H和I，其中提供了更多关于实际考虑和测量方法的信息。该合并版本由第三版（2012年）及其修正案1（2017年）组成。因此，除本出版物外，无需下令修订。

IEC 60118-4:2014+A1:2017 is applicable to audio-frequency induction-loop systems producing an alternating magnetic field at audio frequencies and intended to provide an input signal for hearing aids operating with an induction pick-up coil (telecoil). Throughout this standard, it is assumed that the hearing aids used with it conform to all relevant parts of IEC 60118. This standard specifies requirements for the field strength in audio-frequency induction loops for hearing aid purposes, which will give adequate signal-to-noise ratio without overloading the hearing aid. The standard also specifies the minimum frequency response requirements for acceptable intelligibility. Methods for measuring the magnetic field strength are specified, and information is given on appropriate measuring equipment (see Annex B), information that should be provided to the operator and users of the system (see Annex C), and other important considerations. This standard does not specify requirements for loop driver amplifiers or associated microphone or audio signal sources, which are dealt with in IEC 62489-1, or for the field strength produced by equipment, such as telephone handsets, within the scope of ITU-T P.370. This third edition cancels and replaces the second edition published in 2006. This edition constitutes a technical revision which includes the following significant technical changes with respect to the previous edition: Addition of Annexes G, H and I where more information is provided about practical considerations and methods of measurement. This consolidated version consists of the third edition (2012) and its amendment 1 (2017). Therefore, no need to order amendment in addition to this publication.