Measuring Noise Reduction in Hearing Protective Devices: Labeling Requirements and Guidelines

In the United States, you may come across hearing protection devices, such as earplugs, that are labeled as being compliant with ANSI S3.19-1974. Minimal background information on this document’s current status exists online, so there is a need for further discussion.

It is imperative to protect one’s sensory organs from harm. During operations that expose one to continuous cacophony or any level of loud noises, hearing protective devices can separate personnel from a future in which they cannot perceive the auditory outputs of their surroundings. To assure reliability with their usage, hearing protective devices must be tested properly. This is an issue long confronted by the Acoustical Society of America (ASA), an ANSI-accredited standards developing organization and administrator for the U.S. TAGs (United States Technical Advisory Group) to ISO/TCs 43 and 108.

ANSI S3.19-1974 Noise Reduction Rating (NRR) Labeling

In 1974, ASA released ANSI S3.19-1974: Method for the Measurement of Real-Ear Protection of Hearing Protectors and Physical Attenuation of Earmuffs. 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.

In accordance with ANSI S3.19-1974, 10 human subjects are used for hearing protector evaluations with 9 test frequencies.

ANSI/ASA S12.6-2016

ANSI S3.19-1974 has actually long been superseded, as ANSI S12.6-1984 replaced it over 30 years ago.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.

ANSI/ASA S12.6-2016 was developed and approved by Accredited Standards Committee S12, Noise, under its operating procedures approved by ANSI. The standard specifies the measuring, analyzing, and reporting of the passive noise-reducing capability of hearing protection devices. It includes two testing procedures: Method-A and Method-B.

Method-A is designated trained-subject fit, and it is meant for devices fitted by “individually trained and well-motivated users”, while Method-B, called inexperienced-subject fit, is for devices that are for groups of occupational users.

ANSI/ASA S12.6-2016: Methods for Measuring the Real-Ear Attenuation of Hearing Protectors is available on the ANSI Webstore. You can also read more about the ANSI/ASA S12.6 standard in our past post on the topic.

EPA Regulation for Hearing Protection Device Labeling

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.

You can read the law here: 40 CFR Part 211, Subpart B – Hearing Protective Devices

While ANSI S3.19-1974 remains in effect for labeling requirements of hearing protective devices, it is possible that these requirements could be revised to match those of Method-A in ANSI/ASA S12.6, as well as the content of some other current voluntary consensus standards. If you’d like to learn more about these proposed changes, please refer to: EPA Proposed Revisions to Hearing Protection Standard