ISO/TR 4869-3:1989

Acoustics — Hearing protectors — Part 3: Simplified method for the measurement of insertion loss of ear-muff type protectors for quality inspection purposes

The procedure specified may be used to investigate production spreads of performance as part of type approval or certification procedures and the change of performance with age. It is not intended to be used as the basic test for type approval purposes. Performance data obtained are not to be quoted as representing the real-ear sound attenuation of an ear-muff, nor the protection provided by the ear-muff.