ANSI S3.19-1974

Method for the Measurement of Real-Ear Protection of Hearing Protectors and Physical Attenuation of Earmuffs

This standard specifies the test method for determining the level of noise attenuation (NRR Noise Reduction Rating) of the hearing protection, as recommended by the EPA (U.S. Environmental Protection Agency).

ANSI S3.19-1974 covers the technique for calculating Noise Reduction Rating (NRR), a noise reduction factor, in decibels, that takes into account performance variation of protectors in their effectiveness in reducing noise, due to differing noise spectra, fit variability, and the mean attenuation of test stimuli at the one-third octave band test frequencies.

10 human subjects are required for hearing protector evaluations using 9 test frequencies. The Noise Reduction Rating (NRR) is calculated from these data.

ANSI S3.19-1974 has actually long been superseded, as ANSI S12.6-1984 replaced it over 30 years ago. The current version of this standard is ANSI/ASA S12.6-2016: Methods for Measuring the Real-Ear Attenuation of Hearing Protectors.

While ANSI S3.19-1974 has seen several successors since its original publication, the United States Environmental Protection Agency (EPA) still requires the standard’s NRR testing method through 40 CFR Part 211, Subpart B – Hearing Protective Devices for hearing protective device labeling. As this law, which was first established in 1979, incorporates ANSI S3.19-1974, it includes the standard’s method of 10 human subjects.