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.