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OSHA permits employers to apply age correction when calculating standard threshold shifts — but it is optional, not required, and it comes with an important restriction: age correction is completely prohibited when evaluating whether a hearing loss case is recordable on the OSHA 300 Log. Understanding the difference between these two contexts, how OSHA Appendix F works mechanically, and when age correction helps or hurts your program is essential for any employer running audiometric surveillance under 29 CFR 1910.95.
Soundtrace calculates STS both with and without age correction for every annual audiogram, giving employers full visibility into both the regulatory result and the underlying threshold trend.
Age correction for STS: optional — employer decides. Age correction for 300 Log recordability: prohibited — no exceptions. These are two separate calculations with two separate rules. Applying one has no effect on the other.
Hearing thresholds change over time for two distinct reasons in noise-exposed workers: noise-induced damage to cochlear hair cells, and the normal age-related hearing loss called presbycusis. These two processes overlap on an audiogram and cannot be directly distinguished from each other through audiometric testing alone.
OSHA recognized this challenge when it established the hearing conservation amendment in 1983. Rather than requiring employers to flag every threshold shift — including those attributable to normal aging — as an STS requiring program response, OSHA created Appendix F: a set of age correction tables that allow employers to subtract the expected aging component from an observed threshold change before determining whether an STS has occurred.
The policy rationale is straightforward: if a worker’s threshold at 4000 Hz increased by 8 dB over the past year, but the Appendix F tables indicate that 6 dB of that shift is attributable to the expected effects of aging in someone of that worker’s age and sex, the noise-attributable component is only 2 dB. Flagging this as a noise-related STS would generate program responses — notification, HPD refitting, retraining — that may not be warranted.
Age correction is a statistical estimate, not a clinical diagnosis. The Appendix F tables represent population-average presbycusis rates by age and sex. They do not account for individual variation. A worker whose hearing is deteriorating faster than the table predicts due to noise exposure may have that deterioration masked by age correction. This is why many audiologists and hearing conservation programs choose not to apply age correction, or track results both ways.
Appendix F to 29 CFR 1910.95 provides two tables — one for males, one for females — showing expected hearing threshold values in dB HL at ages 20 through 60+, for each of the three STS frequencies: 2000 Hz, 3000 Hz, and 4000 Hz. These values represent cumulative threshold elevation from audiometric zero attributable to age alone, based on epidemiological data from non-noise-exposed populations.
The tables are not threshold correction values in isolation — they are used comparatively. The age correction for a given year’s STS calculation is the difference between the Appendix F value at the worker’s current age and the Appendix F value at the worker’s age at the time of the baseline audiogram.
| Age | 2000 Hz | 3000 Hz | 4000 Hz |
|---|---|---|---|
| 30 | 3 | 4 | 5 |
| 35 | 4 | 5 | 7 |
| 40 | 5 | 6 | 9 |
| 45 | 6 | 8 | 11 |
| 50 | 8 | 10 | 14 |
| 55 | 10 | 12 | 18 |
| 60 | 13 | 17 | 23 |
The age correction procedure under Appendix F involves four steps. The calculation is done separately for each ear and for each of the three STS frequencies.
Worker profile: Male, age 30 at baseline, now age 40. Annual audiogram shows threshold shifts relative to baseline of: +8 dB at 2000 Hz, +12 dB at 3000 Hz, +10 dB at 4000 Hz. Non-corrected average: +10 dB — apparent STS.
Step 1 — Look up Appendix F values:
At age 30 (baseline): 2000 Hz = 3, 3000 Hz = 4, 4000 Hz = 5
At age 40 (current): 2000 Hz = 5, 3000 Hz = 6, 4000 Hz = 9
Step 2 — Calculate age adjustment per frequency:
2000 Hz: 5 − 3 = 2 dB age adjustment
3000 Hz: 6 − 4 = 2 dB age adjustment
4000 Hz: 9 − 5 = 4 dB age adjustment
Step 3 — Subtract age adjustment from measured shift:
2000 Hz: 8 − 2 = 6 dB age-corrected shift
3000 Hz: 12 − 2 = 10 dB age-corrected shift
4000 Hz: 10 − 4 = 6 dB age-corrected shift
Step 4 — Average the corrected shifts:
(6 + 10 + 6) ÷ 3 = 7.3 dB — below the 10 dB STS threshold. No STS under age correction.
Without age correction, this worker would have triggered STS follow-up. With age correction, no program response is required.
Age adjustment values are always positive (hearing is expected to worsen with age). You only subtract the age adjustment from a measured shift — you never add it. If age correction produces a result below zero for a frequency, use zero for that frequency in the average. You cannot create a “better than baseline” corrected value.
Age correction is most useful for older workers (typically 45+) whose measured threshold shifts are modest and whose audiometric trend is gradual. In these cases, a significant portion of an observed shift may legitimately reflect normal aging rather than accelerated NIHL, and flagging it as an STS would generate unnecessary program responses and PLHCP review referrals.
Manufacturing employers with aging workforces running in-house audiometric programs often apply age correction as a standard practice to reduce the administrative burden of STS responses that their PLHCP would likely attribute to presbycusis anyway.
For younger workers (under 40), the Appendix F age adjustment values are small and age correction makes little practical difference. But for a worker at any age who is experiencing accelerated threshold shift due to inadequate HPD protection, age correction can mask a real noise-induced problem. If a 55-year-old worker is losing hearing faster than the Appendix F tables predict, age correction will reduce or eliminate the apparent STS — and the accelerated noise damage will go unaddressed.
This is the key limitation of age correction as a program tool: it is a population-average estimate, not an individual clinical assessment. Some hearing conservation programs track both age-corrected and non-age-corrected results precisely to catch workers whose rate of threshold progression exceeds the aging prediction.
OSHA does not require you to respond to a non-age-corrected STS if your program policy applies age correction and the age-corrected result is below 10 dB. However, a worker whose non-age-corrected threshold is shifting at 8–9 dB per year consistently should prompt HPD compliance review even if no STS is triggered, because that trend will eventually cross the threshold — and the underlying exposure problem should be addressed now.
This is the most common source of confusion around age correction, and it has significant compliance implications. Under 29 CFR 1904.10(a), a work-related hearing loss case is recordable when the employee’s current audiogram shows an average hearing level of 25 dB or more at 2000, 3000, and 4000 Hz above audiometric zero. No age correction is applied to this calculation, and no age correction is permitted.
The prohibition is explicit and unambiguous. OSHA addressed this when it revised the recordkeeping rule: the 25 dB threshold is measured from audiometric zero without adjustment. The rationale is that recordability is designed to capture the total hearing status of the worker — regardless of cause — to enable population-level surveillance of occupational hearing loss trends. Age correction would systematically undercount recorded cases and defeat this purpose.
| Calculation | Age Correction Permitted? | Threshold | OSHA Reference |
|---|---|---|---|
| STS determination | Yes — optional | 10 dB average shift at 2/3/4 kHz vs. baseline | 1910.95(g)(10)(i) + Appendix F |
| 300 Log recordability | No — prohibited | 25 dB average hearing level at 2/3/4 kHz above audiometric zero | 1904.10(a) |
▶ Bottom line: An employer can use age correction to determine that no STS follow-up is required, but must still evaluate 300 Log recordability without age correction. A single audiogram may require two separate calculations using different methods.
Worker: Male, age 52. Annual audiogram shows average hearing levels (from audiometric zero) of 28 dB at 2000/3000/4000 Hz. Shift from baseline is 12 dB average non-corrected, 8 dB age-corrected.
STS determination (age correction applied): 8 dB corrected average — below 10 dB threshold. No STS. No notification required. No HPD retraining required.
300 Log recordability (no age correction): 28 dB average hearing level above audiometric zero — exceeds 25 dB threshold. Case is recordable if work-related. PLHCP must evaluate work-relatedness. If work-related, record on 300 Log.
This worker requires a 300 Log evaluation even though no STS follow-up is required.
OSHA does not require employers to decide in advance whether to apply age correction — but doing so is strongly advisable. Applying age correction inconsistently — using it when it benefits the employer and not using it otherwise — is indefensible in an OSHA inspection or WC proceeding. The program policy should specify:
Many PLHCP reviewers and hearing conservation programs run both calculations and flag workers whose non-age-corrected shift is progressing toward STS even when the corrected result is below threshold. This provides earlier warning of potential noise exposure problems and documents a more thorough program — which is relevant to both OSHA good-faith reduction factors and WC defense.
OSHA’s age correction framework and state workers’ compensation apportionment rules are separate legal systems with separate methods. Applying Appendix F age correction for OSHA STS purposes does not automatically establish an apportionment defense in WC proceedings — state WC systems have their own age-apportionment rules, methodologies, and evidentiary requirements.
That said, a consistent audiometric record showing gradual threshold progression consistent with presbycusis — documented with both corrected and uncorrected values over multiple years — can be useful evidence in a WC apportionment argument. The key is the consistency and documentation of the longitudinal record, not the application of age correction to any single audiogram.
In contrast, if an employer applied age correction selectively to individual audiograms in ways that appear to minimize STS flags, that pattern could be used against the employer in litigation to show that program responses were avoided by manipulating the calculation method.
▶ Bottom line: Apply age correction consistently according to a documented policy, track both corrected and uncorrected results, and never apply it to 300 Log recordability calculations.
Soundtrace runs age-corrected and non-age-corrected STS calculations simultaneously for every annual audiogram, so your PLHCP reviewer and program coordinator see the full compliance picture — not just the result your policy requires.
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