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HearingHearing

The following list highlights standards related to noise and hearingconservation:The following list highlights standards related to noise and hearingconservation:

1910.95, Occupational noise exposure.1910.95, Occupational noise exposure.

Appendix A, Noise exposure computation.Appendix A, Noise exposure computation.

Appendix B, Methods for estimating the adequacy of hearing protectorattenuation.Appendix B, Methods for estimating the adequacy of hearing protectorattenuation.

Appendix C, Audiometric measuring instruments.Appendix C, Audiometric measuring instruments.

Appendix D, Audiometric test rooms.Appendix D, Audiometric test rooms.

Appendix E, Acoustic calibration of audiometers.Appendix E, Acoustic calibration of audiometers.

Appendix F, Calculations and application of age corrections toaudiograms.Appendix F, Calculations and application of age corrections toaudiograms.

Appendix G, Monitoring noise levels non-mandatory informationalappendix.Appendix G, Monitoring noise levels non-mandatory informationalappendix.

Appendix H, Availability of referenced documents.Appendix H, Availability of referenced documents.

Appendix I, Definitions.Appendix I, Definitions.

1904, Recording and Reporting Occupational Injuries and Illness. [Topic Page]1904, Recording and Reporting Occupational Injuries and Illness. [Topic Page]

1904.10, Recording Criteria for cases involving occupational hearing loss.1904.10, Recording Criteria for cases involving occupational hearing loss.

1926.52, Occupational noise exposure.1926.52, Occupational noise exposure.

When the fluid moves inside the cochlea, thousands ofmicroscopic hair fibers inside the partition wall are putinto motion. There are approximately 24,000 of thesehair fibers, arranged in four long rows.

The hair fibers are all connected to the auditory nerve and, depending onthe nature of the movements in the cochlear fluid, different hair fibersare put into motion. When the hair fibers move they send electricalsignals to the auditory nerve which is connected to the auditory centreof the brain. In the brain the electrical impulses are translated intosounds which we recognize and understand. As a consequence, these hairfibers are essential to our hearing ability. Should these hair fibers becomedamaged, then our hearing ability will deteriorate.

The hearing conservation program requirementis triggered at 85 dBA by both the OSHAstandard in 29 CFR 1910.95(c) and by the latestACGIH TLV. The 85 dBA is considered anaction level in the OSHA standard and isconsidered the TLV for an 8-hour exposure inthe TLVs, but in either case this same leveltriggers the hearing conservation programrequirement.The hearing conservation program requirementis triggered at 85 dBA by both the OSHAstandard in 29 CFR 1910.95(c) and by the latestACGIH TLV. The 85 dBA is considered anaction level in the OSHA standard and isconsidered the TLV for an 8-hour exposure inthe TLVs, but in either case this same leveltriggers the hearing conservation programrequirement.

OSHAOSHA

1910.95(c)(1)1910.95(c)(1)

The employer shall administer a continuing, effectivehearing conservation program, as described inparagraphs (c) through (o) of this section, wheneveremployee noise exposures equal or exceed an 8-hourtime-weighted average sound level (TWA) of 85decibels measured on the A scale (slow response) or,equivalently, a dose of fifty percent. For purposes ofthe hearing conservation program, employee noiseexposures shall be computed in accordance withappendix A and Table G-16a, and without regard toany attenuation provided by the use of personalprotective equipment.The employer shall administer a continuing, effectivehearing conservation program, as described inparagraphs (c) through (o) of this section, wheneveremployee noise exposures equal or exceed an 8-hourtime-weighted average sound level (TWA) of 85decibels measured on the A scale (slow response) or,equivalently, a dose of fifty percent. For purposes ofthe hearing conservation program, employee noiseexposures shall be computed in accordance withappendix A and Table G-16a, and without regard toany attenuation provided by the use of personalprotective equipment.

When the daily noise exposure is composed of two or more periods ofnoise exposure of different levels, their combined effect should beconsidered, rather than the individual effect of each. Exposure to differentlevels for various periods of time shall be computed according to theformula set forth in paragraph (d)(2)(ii) of this section

These definitions apply to the following terms as used inparagraphs (c) through (n) of 29 CFR 1910.95.These definitions apply to the following terms as used inparagraphs (c) through (n) of 29 CFR 1910.95.