00785nam a22000857a 4500245012000000260006900120300001000189505048600199650001400685  aISO 4869-1:1990-Acoustics - Hearing protectors - Part 1: Subjective method for the measurement of sound attenuation  aGeneva :bInternational Organization for Standardization,c1990.  a12 p.  aSpecifies a method for measuring sound attenuation at the threshold of hearing. The procedure is designed to yield values close to the maximum attenuation which are not normally attained under field conditions. The values reflect the attenuating characteristics only to the extent that users wear the device in the same manner as did the test subjects. Data are collected at low sound pressure levels but which are also representative of the values at higher sound pressure levels.  aAcoustics