NOTE: Although the first three (3) pages of this OSHA Instruction CPL
2-2.35A have been cancelled, Appendix A is still vaild.
Noise Control Guidelines
When comparing the relative degree of attenuation of personal protectors and
engineering and/or administrative controls, all of the following factors in
addition to the guidelines in the Field Operations Manual and Industrial
Hygiene Field Operations Manual must be considered and documented in the case
1. Hearing Protection. Personal hearing protection must attenuate
the occupational noise received by the employee's ears to within the levels
specified in Table G-16 of 29 CFR 1910.95. For those employees with a
standard threshold shift (STS), noise reduction must be sufficient to meet
Table G-16a of 29 CFR 1910.95 (85 TWA). Hearing protectors shall be
evaluated for the purposes of analyzing the benefits of engineering controls
a. Use Appendix B of 29 CFR 1910.95 to determine the
laboratory-based noise reduction for a given hearing protector.
b. Apply a safety factor of 50 percent; i.e., divide the calculated
laboratory-based attenuation by 2.
NOTE: This is a general method for taking into consideration OSHA
experience and the published scientific literature, which indicate that
laboratory-obtained attenuation data for hearing protectors are seldom
achieved in the workplace. If a different safety factor seems appropriate in
a particular instance, the ARA for Technical Support should be consulted for
assistance. This procedure is not applicable, however, for determining
compliance with the hearing protector attenuation requirements of the hearing
conservation amendment (29 CFR 1910.95(j)).
c. The adjusted noise reduction should be sufficient to meet Table
G-16 or, as appropriate, Table G-16a. Depending on the specifics of the
case, an exception may be appropriate when an employer is in compliance with
the hearing conservation amendment and has a history of an effective hearing
2. Hearing Loss. Documentation of any hearing loss shall include:
a. The amount of hearing ability lost and date it was
NOTE: If the employer has not done so, apply age correction to
audio-grams according to the guidelines in Appendix F of 29 CFR
b. Exposure level.
c. Frequency and duration of exposure.
d. Length of employment.
e. Explanation of any followup measures taken.
f. Any other pertinent information.
3. Cost of Controls.
a. Resonability. The estimated costs for engineering
controls must be reasonable and include the annualized cost of installing
controls and, if available, the annual cost of their maintenance and costs
due to any resulting loss of productivity or effeciency.
b. Relative Permanency. In order to consider the permanency
of engineering controls, compare the estimated cost for engineering controls
to the estimated annual cost of a hearing conservation program multiplied by
the approximate number of years the controls would be effective.
4. Employee Noise Reduction by Controls. An anticipated reduction
in employee noise exposures would be considered significant if a 3 to 5 dB
decrease is achieved by one or a combination of the following:
a. Source controls.
b. Controlling the industrial environment (e.g., barriers,
c. Administrative controls.
5. Control Options. When evaluation control options for the
purposes of this instruction, consider all types of abatement possibilities.
a. Partial Use of Controls. It may be beneficial to
implement some of the controls while forgoing more costly ones.
b. Substitution. Abatement plans may include plans for
replacing process equipment with quieter equipment that will significantly
reduce exposure levels and make interim engineering controls for existing