BS EN 352-4:2020 pdf free.Hearing protectors一Safety requirements Level-dependent earmuffs.
BS EN 352-4 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.Normative references: The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.EN 352-1:2020, Hearing protectors – General requirements – Part 1: Earmuffs EN 352-3:2020, Hearing protectors – General requirements – Part 3: Earmuffs attached to head protection and/or face protection devices EN 13819-3:2019, Hearing protectors一Testing – – Part 3: Supplementary acoustic test methods 3.1 level-dependent earmuff earmuff fitted with an electronic sound restoration circuit 3.2 sound restoration circuit electroacoustic device intended to reproduce lower level external sounds in the ear canal, and to restrict reproduction of higher level sounds by means of a level-dependent gain function 3.3 criterion level (H) A-weighted sound pressure level of the H noise for which the A-weighted equivalent diffuse-field related sound pressure level, when a level-dependent earmuff is worn and the sound restoration circuit is operating at maximum volume, first exceeds 85 dB(A) 3.4 criterion level (M) A-weighted sound pressure level of the M noise for which the A-weighted equivalent diffuse-field related sound pressure level, when a level-dependent earmuf is worn and the sound restoration circuit is operating at maximum volume, first exceeds 85 dB(A) A-weighted sound pressure level of the L noise for which the A- weighted equivalent diffuse-field related sound pressure level, when a level-dependent earmuf is worn and the sound restoration circuit is operating at maximum volume, first exceeds 85 dB(A) BS EN 352-4 pdf download.