本文件适用于电平相关耳罩。它规定了施工要求， 设计、性能、标记和用户信息与包含的级别有关 功能。 声级相关耳罩设计用于恢复外部声音，同时提供 声音在高音量下的衰减。可选择在间歇或脉冲噪声中使用 以及需要听到外部警告声音的环境。这份文件是 关于那些有电子声音恢复电路的耳罩。购买本文件时可获得的所有当前修订均包含在购买本文件中。

This document is applicable to level-dependent earmuffs. It specifies requirements on construction, design, performance, marking and user information related to the inclusion of the level-dependent functionality. Level-dependent earmuffs are designed to provide restoration of external sounds, while providing attenuation of sounds at high levels. They may be selected for use in intermittent or impulsive noise environments and where external warning sounds are required to be heard. This document is concerned with those earmuffs having an electronic sound restoration circuit.All current amendments available at time of purchase are included with the purchase of this document.