What is a hearing conservation program and why do companies need one?

A hearing conservation program is an OSHA-mandated workplace safety system designed to protect employees exposed to hazardous noise levels. It encompasses noise monitoring, annual audiometric testing, hearing protection fit testing, employee training, and recordkeeping. Companies need one to maintain regulatory compliance, prevent irreversible occupational hearing loss, and reduce long-term workers' compensation liability. Industries from food production to aerospace & defense are required to comply when noise exceeds OSHA thresholds.

What are OSHA's requirements for hearing conservation programs?

OSHA requires employers to implement a hearing conservation program when workers are exposed to noise at or above an 8-hour time-weighted average (TWA) of 85 dBA. Key requirements include annual audiometric testing (audiograms), annual training on the effects of noise, provision and fit testing of hearing protection, ongoing noise exposure monitoring, and thorough recordkeeping. For a complete overview, visit our compliance hub or download the annual compliance checklist.

Which industries are required to implement a hearing conservation program?

Any employer with workers exposed to an 8-hour TWA of 85 dBA or above must comply — this applies under OSHA 1910.95 for general industry and OSHA 1926.52 for construction. High-noise industries include food production, metals & fabrication, automotive parts manufacturing, oil, gas & petrochemical, lumber & wood products, concrete & aggregates, heavy equipment, and aerospace & defense. Browse all covered industries to see how Soundtrace supports each sector.

What are the risks of not having a compliant hearing conservation program?

Non-compliance carries serious consequences: OSHA citations and fines up to $15,625 per violation per day, costly workers' compensation claims for occupational hearing loss, increased legal liability, and reputational damage. Most critically, employees suffer permanent, irreversible hearing loss. Research links untreated hearing loss to broader health risks — learn more in our white paper on hearing loss and health outcomes. Our ROI calculator shows the true cost of non-compliance versus investing in a compliant program.

How do I know if my workplace noise levels require a hearing conservation program?

If employees must raise their voices to be heard at arm's length, noise levels likely exceed OSHA's 85 dBA action level. The definitive way to know is to conduct workplace noise monitoring using calibrated dosimeters or sound level meters. Soundtrace integrates real-time noise monitoring with your audiometric testing program so you can track exposure data and determine compliance requirements in one system. Schedule a demo to see how it works.

Is boothless audiometric testing OSHA-compliant?

Yes — boothless audiometric testing is fully OSHA-compliant when ambient noise levels are controlled and ANSI S3.1 protocols are followed. Soundtrace ensures compliance through real-time ambient noise checks and calibrated equipment at every test frequency. Our proprietary Invisible Booth™ methodology records ambient noise data as proof of a valid test environment. Read our field booth validation white paper for the science behind it, or explore the full audiometric testing feature.

What is a Standard Threshold Shift (STS)?

A Standard Threshold Shift (STS) is a change in hearing threshold of 10 dB or more, averaged across 2000, 3000, and 4000 Hz in either ear, relative to the baseline audiogram. OSHA requires employers to identify STS events and take follow-up action. Soundtrace automatically detects, flags, and tracks STS events through its audiometric testing platform, and all findings are reviewed by licensed audiologists. Proper recordkeeping of STS data is essential for compliance.

Can audiometric testing be conducted without a sound booth?

Yes. OSHA 1910.95 Appendix D sets maximum allowable ambient noise levels for testing environments but does not require a dedicated booth. Soundtrace's audiometer uses noise-attenuating headphones and records real-time ambient noise data at every frequency for every test — what we call the Invisible Booth™ methodology. This approach is validated in our field booth validation white paper and enables compliant testing anywhere, eliminating the need for mobile testing vans.

Can we run hearing tests in-house instead of using a mobile van?

Yes. Soundtrace enables in-house, boothless audiometric testing using calibrated equipment, OSHA-compliant protocols, and automated recordkeeping — eliminating the need for expensive mobile van visits. Our mobile van replacement white paper details how organizations save thousands annually while gaining scheduling flexibility. Use our ROI calculator to estimate your savings, or request a quote.

How often should employees receive audiograms and fit testing?

OSHA requires annual audiograms for all noise-exposed employees, with a baseline test within the first six months of employment in a noise-exposed role. Hearing protection fit testing should be performed at baseline and whenever new hearing protection is issued or if workers report difficulty with proper fit. Soundtrace streamlines both audiometric testing and fit testing into a single workflow, with automated scheduling and compliance recordkeeping.

How do I perform hearing protection fit testing?

Hearing protection fit testing measures how effectively earplugs attenuate noise for an individual worker. Soundtrace provides digital fit testing using PAR (Personal Attenuation Rating) scoring integrated directly into the audiometric testing workflow. After testing, each worker receives a personal attenuation score so you can verify adequate protection. Learn more about compliance requirements or schedule a demo to see fit testing in action.

Why isn't the NRR rating on the earplug box sufficient?

The Noise Reduction Rating (NRR) on earplug packaging is measured under ideal laboratory conditions and significantly overstates real-world protection. OSHA's de-rating method cuts the NRR by 50% for estimating actual attenuation. The only way to verify what protection a specific worker actually receives is to conduct individual fit testing and obtain a Personal Attenuation Rating (PAR). Soundtrace integrates fit testing with audiometric testing for a complete worker protection profile.

What's the best way to monitor noise exposure in the workplace?

The most effective approach is continuous, real-time noise monitoring using calibrated dosimeters placed on workers across shifts and areas. Soundtrace integrates noise exposure data with hearing test results and fit testing scores to give safety teams a complete picture of risk. This data feeds into compliance dashboards and automated recordkeeping. Request a quote to learn more.

How often must employers provide hearing conservation training?

OSHA 1910.95(k) requires annual hearing conservation training for all workers exposed at or above the 85 dBA action level. Training must cover the effects of noise on hearing, the purpose and proper use of hearing protectors, and the purpose of audiometric testing. Soundtrace includes built-in training modules that satisfy OSHA requirements and automatically track completion for recordkeeping. See our annual training page for details.

How long must audiometric records be retained?

OSHA 1910.95(m) requires audiometric test records to be retained for the duration of the affected worker's employment. Industry best practices recommend retaining records for at least 30 years after employment ends. Soundtrace stores all records in a SOC 2-certified, HIPAA-compliant cloud platform with permanent retention through our automated recordkeeping system. Learn more about data protection on our security page, or review our data security white paper.

What does the Soundtrace platform include?

Soundtrace is an all-in-one hearing conservation platform that includes boothless audiometric testing, hearing protection fit testing, noise exposure monitoring, STS tracking, OSHA training modules, and automated compliance recordkeeping — plus licensed audiologist oversight. Explore all platform features or schedule a demo to see it in action.

What is the best digital solution for hearing conservation compliance?

Soundtrace is the leading all-in-one digital platform for hearing conservation compliance. It combines audiometric testing, real-time noise monitoring, earplug fit testing, STS tracking, and OSHA-compliant recordkeeping in a single system. Read customer case studies to see results, or learn why organizations switch to Soundtrace.

Who serves as the Professional Supervisor for a Soundtrace-managed program?

Soundtrace's Chief Medical Officer, Dr. Subinoy Das, serves as the licensed Professional Supervisor for all client hearing conservation programs. All Standard Threshold Shift reviews and medical referral decisions are made by licensed audiologists through the Soundtrace cloud platform. This audiologist oversight is built into every audiometric testing workflow. Learn more about our team or review our trust & credentialing page.

How does Soundtrace reduce costs compared to traditional mobile testing vans?

Soundtrace eliminates the need for travel, mobile van scheduling, and production downtime by enabling on-site boothless testing at any time. Organizations typically save 40–60% per test compared to mobile van providers. Our mobile van replacement white paper details the cost breakdown, and the ROI calculator lets you estimate your savings. Request a quote for custom pricing.

How quickly can an organization roll out a hearing conservation program using Soundtrace?

Most organizations launch their Soundtrace-powered program in weeks, not months. With boothless testing, built-in training modules, and automated recordkeeping, safety teams can start testing employees and generating compliance records almost immediately. Schedule a demo to see how fast onboarding works, or request a quote to get started.

How is STS calculated?

Take the worker's annual audiogram results at 2000, 3000, and 4000 Hz in one ear. Subtract the baseline values at the same frequencies. Average those three shifts. If the average is 10 dB or greater (after optional age correction), it's an STS in that ear. The same calculation is repeated for the other ear. Either ear meeting the threshold is enough.

What is OSHA Appendix F age correction, and is it required?

OSHA 29 CFR 1910.95 Appendix F provides tables of expected age-related hearing change for males (Table F-1) and females (Table F-2) by year of age at 1000, 2000, 3000, 4000, and 6000 Hz. Age correction is permitted but not required: you subtract the difference between the age-now correction and the age-at-baseline correction from the observed shift, isolating the noise-induced portion. If the corrected average is still ≥10 dB, it's an STS. If correction reduces the shift below 10 dB, it is not an STS for OSHA purposes.

When is an STS recordable on the OSHA 300 log?

Per 29 CFR 1904.10, an STS becomes recordable on the OSHA 300 log only when both: (1) an STS has occurred (≥10 dB average shift at 2k/3k/4k Hz in either ear, optionally age-corrected), AND (2) the worker's total hearing level in the same ear is 25 dB or more above audiometric zero, averaged at 2000, 3000, and 4000 Hz. Both conditions must be met in the same ear.

What's the difference between OSHA STS and OSHA recordability?

STS triggers employer follow-up obligations under the noise standard (1910.95): retest, notification, fitted hearing protection, training. Recordability is a separate determination under 1904.10 that only happens when the STS is also accompanied by 25+ dB of total hearing loss in the same ear. Many STS cases are not recordable. All recordable hearing-loss cases require an STS first.

What should I do if a worker has an STS?

Within 21 days of confirming the STS: (1) notify the worker in writing, (2) ensure the worker is using fitted hearing protection (a fit test with a real PAR is best), (3) retrain on hearing conservation, (4) refer for a clinical audiological evaluation if the audiologist or physician recommends it, and (5) re-evaluate the workplace noise control measures. If you obtained a retest within 30 days that confirms the original result, the original test becomes the official annual audiogram.

Can a worker have an STS in only one ear?

Yes. STS is calculated per ear. If the average shift at 2k/3k/4k Hz in either ear is ≥10 dB, the worker has an STS — even if the other ear is unchanged. The follow-up requirements (notification, retest, fitted protection, retraining) all apply once an STS is found in either ear.

How accurate is this STS calculator?

The math is exact. The calculator uses the OSHA-defined STS formula (mean shift at 2k/3k/4k Hz) and the official Appendix F age-correction tables. The accuracy of the result depends on accurate audiogram data — calibrated audiometers, a quiet test environment, and a properly trained tester. Soundtrace runs every audiogram through automated STS calculation, age correction, and OSHA 300 recordability flagging — all tied to each worker's noise exposure record.

Free Tool · 29 CFR 1910.95 & 1904.10

OSHA STS Calculator

Enter a worker's baseline and current audiogram. We'll calculate Standard Threshold Shift per ear, apply OSHA Appendix F age correction, and tell you whether the case is OSHA 300 recordable — instantly.

OSHA STS Calculator

Standard Threshold Shift with Appendix F age correction

Step 1

Worker info & age correction

OSHA 1910.95 Appendix F lets you subtract expected age-related hearing change from the observed shift.

Apply Appendix F age correction

Sex

Age at baseline test

yrs

Age at current test

yrs

Step 2

Enter audiogram thresholds (dB HL)

STS is calculated from the average shift at 2000, 3000, and 4000 Hz in either ear.

Ear / Test	500	1k	2k	3k	4k	6k	8k
R · Baseline
R · Current
L · Baseline
L · Current

Highlighted columns (2k/3k/4k Hz) are the STS calculation frequencies.Audiogram thresholds must be in 5 dB steps from −10 to 110 dB HL.

Step 3 — Results

Per-ear STS analysis

No STS in either ear

Right ear

No STS

Observed avg

+11.7 dB

Age-corrected

+9.7 dB

Hearing level avg

25.0 dB

Average shift 9.7 dB < 10 dB threshold → no STS in this ear.

Left ear

No STS

Observed avg

+5.0 dB

Age-corrected

+3.0 dB

Hearing level avg

18.3 dB

Average shift 3.0 dB < 10 dB threshold → no STS in this ear.

For a real OSHA-compliant determination, every audiogram must be reviewed by a professional supervisor (audiologist, otolaryngologist, or qualified physician) per 1910.95(g)(3). Soundtrace handles all STS math, age correction, recordability flagging, and professional review for every annual audiogram automatically.

The Math

How OSHA Calculates an STS

Two formulas — one for STS, one for OSHA 300 recordability. Both come straight from the regulation.

Step 1

Per-frequency shift

For each ear, compute the shift at 2000, 3000, and 4000 Hz:shift_f = current_f − baseline_f

Step 2

Age correction (optional)

Subtract age-related expected change per Appendix F:corrected_f = shift_f − (Age_now − Age_base)

Step 3

Average & compare

Average the three corrected shifts. If ≥10 dB, it's an STS:STS = (s_2k + s_3k + s_4k) / 3 ≥ 10 dB

When does an STS become OSHA 300 recordable?

Per 29 CFR 1904.10, an STS becomes a recordable hearing-loss case only if both conditions are met in the same ear:

An STS has occurred (≥10 dB average shift at 2k/3k/4k Hz, age-corrected if used).
The worker's current hearing level is ≥25 dB above audiometric zero, averaged at 2k/3k/4k Hz.

See the full OSHA 300 / recordkeeping requirements →

Free Tools That Pair With This

STS Is the Effect. Find the Cause.

An STS tells you the worker's hearing is shifting. The next questions are: how loud is the workplace, and is the hearing protection actually doing enough?

Free Tool

OSHA TWA Calculator

Calculate the worker's 8-hour Time-Weighted Average noise exposure to identify whether they're over the 85 dBA Action Level or 90 dBA PEL.

Free Tool

NRR Derating Calculator

OSHA and NIOSH derating to estimate real-world hearing protection. If protected exposure is still ≥85 dBA, an STS becomes far more likely.

Take the Next Step on STS

Deeper material from Soundtrace's research library, plus the OSHA features and industry guides that put STS in context.

How Soundtrace Handles It

Audiometric Testing

Boothless, OSHA-compliant audiograms with automatic STS math built in.

OSHA Recordkeeping

Auto-generated 300 log entries the moment a recordable case is confirmed.

HPD Fit Testing

Replace labeled NRR with a real Personal Attenuation Rating per worker.

Research & Deep Dives

Hearing Loss & Health Outcomes

Why early STS detection matters far beyond OSHA recordability.

Field Booth Validation Study

Boothless audiometry vs. ANSI booth: STS detection accuracy compared.

OSHA ITA Hearing-Loss Database

Search every recordable hearing-loss case OSHA published in the ITA.

Industries Where STS Cases Are Common

Metals Fabrication Heavy Equipment Automotive Parts Oil, Gas & Petrochemical Lumber & Wood Products Food Production Concrete & Aggregates All Industries

Reference & Compliance Tools

OSHA HCP Annual Checklist

Every line item OSHA inspectors verify, including STS follow-up.

Mobile Hearing Testing

Replace mobile vans with on-site Invisible Booth™ testing.

STS Employer Guide

Plain-English walkthrough of every employer obligation when an STS occurs.

Common Questions

STS Calculator FAQ

Everything you need to know about Standard Threshold Shift, age correction, and OSHA 300 recordability.

Per OSHA 29 CFR 1910.95(g)(10), a Standard Threshold Shift 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. STS is the legal trigger that requires employer follow-up: notification of the worker, audiogram retest within 30 days, fitted hearing protection, and (if confirmed) a recordable entry on the OSHA 300 log when the criteria in 29 CFR 1904.10 are met.

Stop calculating STSs by hand

Soundtrace runs every annual audiogram through automated STS math, OSHA Appendix F age correction, and 1904.10 recordability flagging — and ties the result back to the worker's noise exposure record. No spreadsheets. No missed cases. OSHA 300 entries pre-filled.

See How Audiometric Testing Works Talk to a CAOHC-certified OHC