COHC key terms

A written employer program required when noise exposure reaches or exceeds 85 dBA as an eight-hour time-weighted average, covering monitoring, audiometric testing, hearing protection, training, and recordkeeping.

The 85 dBA eight-hour time-weighted average exposure that triggers most hearing conservation requirements under OSHA, including monitoring, audiometric testing, training, and offering hearing protectors to employees.

OSHA's maximum allowable noise exposure, 90 dBA as an eight-hour time-weighted average with a 5 dB exchange rate; exposures above this level require feasible engineering or administrative controls.

Requirement that employees wear hearing protectors when exposed above the permissible exposure limit, when not yet tested, or when a standard threshold shift has occurred.

A physician or audiologist who oversees the hearing conservation program, reviews audiometric results, interprets problem audiograms, and decides whether referral or follow-up is needed.

OSHA requirement that each employee exposed at or above the action level receive a valid audiogram within six months of the baseline and at least annually thereafter.

An instrument with a microphone and calibrated amplifier that measures sound pressure level at a location; useful for area surveys but it does not capture a worker's full-shift personal exposure.

A wearable instrument worn near the ear that records sound levels throughout a work shift and computes a time-weighted average, capturing the worker's actual varying exposure.

The steady sound level that, averaged over a defined period such as eight hours, represents the same noise dose as a worker's varying exposure.

The sound level increase that halves the allowed exposure duration; OSHA uses 5 dB, so every 5 dB rise cuts permissible exposure time by half.

A frequency filter that approximates the sensitivity of the human ear at moderate sound levels, used for most occupational noise measurements and hearing conservation decisions.

The maximum instantaneous sound pressure during an exposure, measured without averaging; OSHA limits peak exposure to 140 dB regardless of duration.

A brief, sharp sound such as a gunshot, hammer strike, or blast that rises and falls rapidly; it is more damaging than steady noise carrying the same total energy.

The eardrum, a thin membrane that vibrates when sound waves strike it and passes that motion to the bones of the middle ear.

The three tiny middle-ear bones, the malleus, incus, and stapes, which amplify and transmit eardrum vibrations to the fluid-filled inner ear.

The snail-shaped, fluid-filled organ of the inner ear containing sensory hair cells that convert sound vibrations into nerve signals sent to the brain.

Sensory cells in the organ of Corti whose microscopic stereocilia bend in response to sound; noise damage or loss of these cells is permanent and irreversible.

Permanent hearing loss caused by accumulated loud sound exposure, usually beginning at higher frequencies and worsening with continued exposure; it is preventable but not medically reversible.

A reversible rise in hearing threshold after loud sound exposure that gradually recovers, often within hours to days; repeated episodes may lead to permanent loss.

An irreversible elevation of hearing threshold caused by damage to sensory cells or nerve fibers; it does not recover and is the outcome hearing conservation aims to prevent.

Age-related hearing loss, usually gradual and greatest at high frequencies, that can be mistaken for noise-induced loss and is addressed through age correction in audiogram comparison.

Ringing, buzzing, or other sound perceived without an external source; it commonly accompanies noise-induced hearing loss and can be an early warning of cochlear damage.

Testing in which tones of specific frequencies are presented at controlled levels to find the softest level a person can hear, producing a threshold audiogram.

A sound-treated enclosure with controlled background noise that keeps ambient sound below required limits at each test frequency so threshold testing remains valid.

The lowest sound level at which a listener responds to a test tone in a specified proportion of presentations, recorded in decibels hearing level for each frequency.

The standard ascending threshold procedure: after each response the level is lowered 10 dB, and after no response it is raised 5 dB, bracketing the threshold.

Visual inspection of the ear canal and eardrum before audiometry to detect wax, drainage, or structural problems that could invalidate testing or require medical referral.

Laboratory measurement of an audiometer's output levels and frequencies using a sound-level meter and acoustic coupler to verify accuracy across the required frequency range.

A routine listening test in which a person with stable hearing is tested on the audiometer to confirm that output is reasonable and has not changed noticeably.

A quick check of the audiometer before testing, listening for correct tone quality, clean switches, and absence of distortion, crackles, or unexpected noise.

A change from baseline of at least 10 dB averaged at 2000, 3000, and 4000 Hz in either ear, triggering notification, protector refitting, and follow-up.

The initial audiogram used as the reference for later comparisons, ideally obtained before noise exposure begins and after enough quiet time away from workplace noise.

Replacing the original baseline with a later audiogram when it is more medically appropriate, such as when the first test was unreliable or a persistent improvement is documented.

Adjusting audiometric comparisons for expected hearing loss from aging, so a standard threshold shift is attributed to workplace noise rather than to normal aging.

A single-number laboratory rating of a hearing protector's attenuation; it is combined with derating and exposure data to estimate protected exposure in the workplace.

A measure of how well a specific hearing protector fits an individual worker, obtained through fit testing rather than relying on a laboratory rating alone.

A procedure that measures real-world attenuation for a worker wearing a specific protector, revealing leaks and teaching better insertion so protection matches the assumed value.

Wearing earplugs and earmuffs together when exposure exceeds limits even with one protector; combined attenuation is estimated as the higher protector's rating plus a small added amount.

Periodic review of hearing conservation activities using audiometric trends, exposure data, and training records to judge effectiveness and make improvements.

Maintaining noise measurements, audiograms, and training records for required periods so compliance, exposure trends, and each employee's hearing history can be verified.