Review of the 2016 Edition of ANSI S12.6 and its place in the panoply of standards on the measurement of real-ear attenuation at threshold since 1957

Abstract

The American standard specifying the procedure for the measurement of real-ear attenuation at threshold (REAT), often termed the gold standard in measuring hearing protector attenuation, was recently approved as an updated version, ANSI 12.6-2016. REAT was first standardized worldwide in the late 1950s in an American standard ANSI Z24.22-1957 and the method has evolved with time. Changes have affected the electroacoustic requirements for the sound field, instrumentation, audiometric method, and permissible background noise, but more importantly have also improved the specification of how the experimenter works with and fits the test subjects. So too, estimates of uncertainty are now included, and in the 2016 version they have been clarified and brought into harmony with ISO 4869-1. The author, who has been the chair since 1985 of the ANSI working group responsible for S12.6, will compare and contrast the various methods and present representative data as well as a discussion of the expanded uncertainties that are specified. Those values, for the 1/3-octave band test bands from 125 Hz to 8000 Hz, vary from approximately 1.5-2 dB for earmuffs and 2-3 dB for earplugs for within-laboratory testing, to 4-6 dB for earmuffs and 6.5-8 dB for earplugs for between laboratory measurements.