scope:

This document is applicable to level-dependent earplugs. It specifies requirements on construction, design, performance, marking and user information related to the inclusion of the level-dependent functionality.

Level-dependent earplugs 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 earplugs having an electronic sound restoration circuit.