Hearing Conservation Programs Under OSHA 1910.95: Audiograms and Standard Threshold Shifts

NIOSH estimates that about 22 million U.S. workers are exposed to hazardous noise on the job every year (NIOSH). In healthcare that noise hides in places people forget to measure: central sterile processing, plant operations, the boiler room, kitchen dish rooms, grounds and maintenance shops. If any of those crews are logging exposures near the action level, you owe them a hearing conservation program — and the OSHA hearing conservation program rules in 29 CFR 1910.95 are specific about what that entails.

This is a walk-through for the person who actually runs the program: the occ-health nurse, the safety officer, the clinic manager. I'll keep the paragraph citations inline so you can drop them straight into your written policy.

When is a hearing conservation program required?

Two numbers trip people up, and they are not the same number.

The permissible exposure limit (PEL) is a 90 dBA 8-hour time-weighted average, per Table G-16 at 1910.95(b)(1). OSHA uses a 5-dB exchange rate: halve the allowed duration for every 5-dB jump. So 90 dBA is fine for 8 hours, 95 dBA for 4 hours, 100 dBA for 2 hours.

The action level is lower — an 8-hour TWA of 85 dBA, equivalently a 50% dose, defined at 1910.95(c). This is the trigger everyone misses. The full hearing conservation program kicks in at 85, not 90. You do not get to wait until exposures blow past the PEL.

When information indicates any employee's exposure may reach that 85 dBA TWA, you must develop and implement a noise exposure monitoring program to identify who belongs in the program and to guide hearing-protector selection (1910.95(d)). A useful NIOSH rule of thumb for deciding when to pull out a dosimeter: if a worker has to raise their voice to be understood by someone about an arm's length away, noise is likely at or above the action level and sampling is warranted. It's a screening cue, not a substitute for measurement — don't guess, measure.

The full program has five elements, and an auditor will look for all five:

• Noise exposure monitoring — dosimetry or area sampling to identify at-risk employees
• Audiometric testing — baseline and annual audiograms
• Hearing protectors — offered, fitted, and enforced
• Training — annual, for everyone in the program
• Recordkeeping — exposure and audiometric records, retained per the rule

A best-practice note on exchange rate

OSHA's 5-dB exchange rate and 90 dBA PEL are the legal floor. NIOSH recommends a more protective 85 dBA REL using a 3-dB exchange rate (NIOSH). The 3-dB rule tracks equal-energy dose more accurately, so intermittent high-level noise is weighted more heavily. If you're writing a program from scratch, building it to the NIOSH standard costs little and protects more. It also matters because the stakes are real: among workers with hearing difficulty, NIOSH data suggest roughly 1 in 4 cases is attributable to occupational exposure (CDC MMWR).

Baseline vs. annual audiograms

The baseline audiogram is the reference every future test is measured against, so getting it clean matters more than any single annual.

Establish it within 6 months of an employee's first exposure at or above the action level (1910.95(g)(5)(i)). If you use a mobile test van, you get up to 1 year — but the employee must wear hearing protectors for any time beyond six months after first exposure until the baseline is done (1910.95(g)(5)(ii)).

The catch people forget: a baseline must be preceded by at least 14 hours without workplace noise (1910.95(g)(5)(iii)). Hearing protectors count toward meeting that requirement, but the cleaner move is to test before the shift or after a day off. A baseline recorded on a worker who came straight off the floor is a baseline shifted by temporary threshold shift — you'll spend years chasing phantom changes against it.

After the baseline, run a new audiogram at least annually for each employee exposed at or above the 85 dBA TWA (1910.95(g)(6)). Each annual is compared back to the baseline to check validity and screen for a shift — and that comparison may be performed by a technician (1910.95(g)(7)(i)), not necessarily a physician or audiologist.

You can also revise the baseline — for a persistent STS, or when thresholds have significantly improved — so future comparisons run against a more representative reference (1910.95(g)(9)).

What is a standard threshold shift?

Here is the definition verbatim, because the wording is exact. A standard threshold shift (STS) is a change in hearing threshold, relative to the baseline audiogram, of an average of 10 dB or more at 2000, 3000, and 4000 Hz in either ear (1910.95(g)(10)(i)). "Either ear" — one ear crossing the line is an STS.

When determining whether an STS occurred, you may age-correct the annual audiogram for presbycusis using the procedure in Appendix F, per 1910.95(g)(10)(ii). Hold that thought — it does not carry over to the OSHA 300 log.

Once you have a shift, the clock starts:

1. Optional 30-day retest. If the annual shows an STS, you may retest within 30 days and use the retest as the annual (1910.95(g)(7)(ii)). Temporary shifts resolve; a genuine one won't. Retesting before you notify avoids false alarms.
2. 21-day written notice. On a confirmed STS, inform the employee in writing within 21 days of the determination (1910.95(g)(8)(i)).
3. Fit or refit protectors. Employees who haven't been in the program get protectors that attenuate to a 90 dBA TWA (1910.95(j)(2)); STS employees must be refitted to attenuate to 85 dBA or below (1910.95(j)(3)).
4. Refer for clinical evaluation where the audiologic findings warrant it.

And don't forget training happens every year for everyone in the program, not just after a shift (1910.95(k)(2)).

Recordkeeping — and the STS-vs-300-log trap

Retention is split by record type under 1910.95(m)(3): noise exposure measurement records for 2 years, and audiometric test records for the duration of the affected employee's employment. Losing an audiogram after someone retires is not the goal — these follow the worker's whole tenure.

Now the part that generates the most confusion in healthcare clinics: an STS is not automatically OSHA-recordable. Under 29 CFR 1904.10(a), a hearing loss goes on the OSHA 300 log only when both are true — an STS occurred and the total hearing level is 25 dB or more above audiometric zero (averaged at 2000/3000/4000 Hz) in the same ear as the STS.

The trap is age correction. You may age-correct for the STS determination, but you may not age-correct when checking the 25-dB-above-zero threshold for recordability (1904.10(b)). Two different tests, two different rules. Apply age correction to the wrong one and you'll either over-record or miss a recordable — both get flagged in an audit.

What non-compliance costs

As of early 2026, OSHA's maximum civil penalties stand at $16,550 per serious violation and $165,514 per willful or repeat violation (with $16,550 per day for failure to abate), per OSHA's penalties schedule. The exposure is per violation, and hearing programs cite easily on missed baselines and late notifications, so a single lapsed cohort can multiply quickly.

FAQ

We only have a few maintenance staff near 85 dBA. Do we really need the full program? Yes. The action level at 1910.95(c) is per-employee, not a facility average. If even one worker's 8-hour TWA reaches 85 dBA, that person is in the program — monitoring, baseline within six months, annual audiogram, protectors, and annual training.

An employee shows a 10 dB shift on the annual. Do I have to report it right away? Not immediately. You may retest within 30 days and use that as the annual (1910.95(g)(7)(ii)). If the retest confirms the STS, then the 21-day written notification and refitting obligations apply.

Can the same audiogram be an STS but still not land on the OSHA 300 log? Yes — that's the most common mistake. An STS only becomes recordable if the same ear is also 25 dB or more above audiometric zero, with no age correction on that second test (1904.10).

Where hearing conservation programs slip is rarely the audiometry itself — it's the calendar. Baselines that drift past six months, annuals that lapse, 21-day notices that quietly blow their deadline. The practical defense is a single tracked list: who is enrolled, when each baseline and annual is due, and where each STS follow-up stands. Whether you keep that in a spreadsheet or a dedicated occupational-health system like carefoundryESC, the test is the same — when the auditor asks for the file, the dates and the notifications line up.

This article is general guidance, not legal advice. Confirm the current regulation text against OSHA and your state plan before finalizing policy.