NF EN 24869-1 : 1993

Committees responsible
National foreword
Method
1. Scope
2. Normative references
3. Definitions
4. Measurement of the sound attenuation of hearing
     protectors
Annexes
A. Uncertainty of sound attenuation measurements
B. Bibliography
Tables
1. Allowable field variation for different microphones
2. Maximum permissible background sound pressure level
3. Minimum and maximum sound pressure levels for test
     signals
A.1 Repeatability and reproducibility of sound
     attenuation measurements on ear-muffs at a
     probability level of 95% (according to ISO 5725)
A.2 Repeatability and reproducibility of sound
     attenuation measurements on ear-plugs at a
     probability level of 95% (according to ISO 5725)

Describes a method for measuring sound attenuation of hearing protectors at the threshold of hearing, to yield values close to the maximum attenuation which are not normally attained under field conditions. This has been adopted because the attenuation values can then be consistently reproduced. This method provides data which are collected at low sound pressure levels but which are also representative of attenuation values at higher levels. An exception is amplitude-sensitive hearing protectors for sound pressure levels above the point at which their level-dependent characteristics become effective. At this level the method specified is inapplicable.