Appendix B to Part 227 - Methods for Estimating the Adequacy of Hearing Protector Attenuation
49:4.1.1.1.21.4.15.1.43 : Appendix B
Appendix B to Part 227 - Methods for Estimating the Adequacy of
Hearing Protector Attenuation
This appendix is mandatory.
Employers must select one of the following three methods by
which to estimate the adequacy of hearing protector
attenuation.
I. Derate by Type
Derate the hearing protector attenuation by type using the
following requirements:
A. Subtract 7 dB from the published Noise Reduction Rating
(NRR).
B. Reduce the resulting amount by:
1. 20% for earmuffs,
2. 40% for form-able earplugs, or
3. 60% for all other earplugs.
C. Subtract the remaining amount from the A-weighted TWA. You
will have the estimated A-weighted TWA for that hearing
protector.
II. Method B From ANSI S12.6-1997 (Reaffirmed 2002)
Use Method B, which is found in ANSI S12.6-1997 (Reaffirmed
2002) “Methods for Measuring the Real-Ear Attenuation of Hearing
Protectors.” The Director of the Federal Register approves the
incorporation by reference of this standard in accordance with 5
U.S.C. 552(a) and 1 CFR part 51. You may obtain a copy of the
incorporated standard from the American National Standards
Institute at 1819 L Street, NW., Washington, DC 20036, or
http://www.ansi.org. You may inspect a copy of the
incorporated standard at the Federal Railroad Administration,
Docket Room, 1200 New Jersey Avenue, SE., Washington, DC 20590, or
at the National Archives and Records Administration (NARA). For
information on the availability of this material at NARA, call
202-741-6030, or go to
http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
III. Objective Measurement
Use actual measurements of the level of noise exposure (as an
A-weighted SLOW response dose) inside the hearing protector when
the employee wears the hearing protector in the actual work
environment.
[71 FR 63123, Oct. 27, 2006, as amended at 74 FR 25173, May 27,
2009]