本文件涉及主动降噪（ANR）耳罩。它规定了确定有源插入损耗的试验方法和推导总衰减的计算程序。为此，被动模式下的声衰减值也必须已知，并根据ISO 4869-1确定。这些方法适用于稳定的噪声暴露，不适用于含有脉冲成分的噪声。 这些测试方法分别使用ISO 4869-1和ISO 11904-1中规定的被动（RET）和主动麦克风实耳（MIRE）测量来解释佩戴者和设备之间的声学相互作用。

This document is concerned with active noise reduction (ANR) earmuffs. It specifies the test methods for the determination of the active insertion loss and calculation procedures for deriving the total attenuation. For this aim, the values of sound attenuation in the passive mode also have to be known and are determined according to ISO 4869 1. These methods are intended for steady noise exposures and are not applicable to noises containing impulsive components. The test methods account for the acoustical interaction between the wearer and the device using measurements of passive (REAT) and active microphone-in-real-ear (MIRE) measurements as specified in ISO 4869 1 and ISO 11904 1, respectively.