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 OSHA's 8-hour TWA calculated?

OSHA uses a 5 dB exchange rate. The permissible time at any sound level L is T = 8 / 2^((L − 90)/5). Daily noise dose D (as a percentage) equals 100 × Σ (Cᵢ / Tᵢ), where Cᵢ is the actual time spent at level Lᵢ and Tᵢ is the OSHA permissible time at that level. The 8-hour TWA in dBA is then 16.61 × log₁₀(D / 100) + 90.

What's the difference between OSHA and NIOSH TWA?

OSHA uses a 5 dB exchange rate with a 90 dBA Permissible Exposure Limit (PEL) and an 85 dBA Action Level. NIOSH uses a more protective 3 dB exchange rate with an 85 dBA Recommended Exposure Limit (REL). For the same noise data, the NIOSH TWA is almost always higher than the OSHA TWA, which is why workers can be compliant under OSHA while still accumulating real hearing damage risk under NIOSH criteria.

What is the OSHA Action Level vs. the PEL?

The Action Level is an 8-hour TWA of 85 dBA — once a worker reaches it, the employer must enroll them in a hearing conservation program (monitoring, audiometric testing, hearing protection availability, training). The Permissible Exposure Limit (PEL) is an 8-hour TWA of 90 dBA — at or above the PEL, hearing protection use is mandatory and engineering or administrative controls are required.

What is daily noise dose, and how does it relate to TWA?

Daily noise dose is the percentage of the maximum allowable daily noise exposure a worker has accumulated. A dose of 100% corresponds to OSHA's PEL of 90 dBA TWA; a dose of 50% corresponds to the 85 dBA Action Level. Doses above 100% mean the worker has exceeded OSHA's PEL for the day. Dose and TWA are mathematically equivalent — they're just two ways of expressing the same exposure.

Do levels below 80 dBA count toward OSHA TWA?

No. OSHA's TWA calculation only includes sound levels of 80 dBA and above. Quieter periods of the shift are treated as contributing zero dose. NIOSH's REL calculation, in contrast, includes all sound levels at or above 80 dBA (and some methods include levels down to 75 dBA), which is one reason NIOSH TWAs run higher.

How accurate is this TWA calculator?

The math is exact. The calculator uses OSHA's official formulas from 29 CFR 1910.95 Appendix A and NIOSH's 1998 Criteria Document equations. The accuracy of the result depends entirely on how representative your noise level and time inputs are. For an OSHA-compliant TWA on a real worker, you need calibrated dosimetry data sampled across a full shift — not estimates. Soundtrace's connected dosimetry handles that automatically and ties each TWA to the worker's audiometric record.

What if my worker is exposed to noise for more than 8 hours?

OSHA's TWA still normalizes to an 8-hour shift, but the dose accumulates over the actual shift length. Add all exposure periods (even those beyond the 8th hour) to this calculator — the dose calculation handles shifts longer than 8 hours correctly, and the resulting TWA reflects that extra exposure.

Free Tool · 29 CFR 1910.95

OSHA TWA Calculator

Enter a worker's noise levels and exposure times. We'll compute the OSHA 8-hour Time-Weighted Average, daily dose, and NIOSH equivalent — instantly.

OSHA TWA Calculator

8-hour Time-Weighted Average noise exposure

Step 1

Enter the worker's noise exposure

For each period of the shift, enter the noise level in dBA and how many hours the worker spent at that level.

Noise Level (dBA)

Hours at Level

OSHA Allowed

dBA

6.06 hr

dBA

10.56 hr

Total shift time entered: 8.00 hours

Step 2 — Results

Your worker's TWA noise exposure

Exceeds OSHA PEL (90 dBA)

OSHA 8-hr TWA

90.3dBA

5 dB exchange rate, 90 dBA criterion (29 CFR 1910.95 App. A)

NIOSH 8-hr TWA

90.4dBA

3 dB exchange rate, 85 dBA REL (NIOSH 1998 Criteria)

OSHA Daily Dose

104%

0%50% (AL)100% (PEL)200%

This worker exceeds OSHA's 90 dBA PEL. Engineering or administrative controls are required to reduce exposure, and hearing protection use is mandatory. The worker must remain enrolled in your hearing conservation program with annual audiometric testing.

For an OSHA-compliant TWA on a real worker, you need calibrated dosimetry across a full shift — not estimates. Soundtrace's connected dosimetry calculates this automatically and ties each TWA to the worker's audiometric record.

The Math

How OSHA Calculates 8-Hour TWA

The exact formulas from 29 CFR 1910.95 Appendix A — applied automatically by the calculator above.

Step 1

Permissible time at each level

T = 8 / 2^{(L − 90)/5}

At 90 dBA the OSHA permissible time is 8 hours. Every 5 dB increase cuts allowable time in half — so 95 dBA = 4 hr, 100 dBA = 2 hr, 105 dBA = 1 hr.

Step 2

Daily noise dose

D = 100 × Σ (C_i / T_i)

Sum the actual time at each level (Cᵢ) divided by the permissible time (Tᵢ) at that level, then multiply by 100. 100% dose = OSHA PEL. 50% dose = Action Level.

Step 3

Convert dose to TWA

TWA = 16.61 × log₁₀(D/100) + 90

Convert the dose percentage into an 8-hour Time-Weighted Average in dBA. This is the single number OSHA uses to classify exposure against the 85 dBA Action Level and 90 dBA PEL.

Reference table (OSHA 5 dB exchange rate): 85 dBA → 16 hr · 90 dBA → 8 hr · 95 dBA → 4 hr · 100 dBA → 2 hr · 105 dBA → 1 hr · 110 dBA → 30 min · 115 dBA → 15 min

Why Two TWAs?

OSHA vs NIOSH — They're Not the Same

OSHA's TWA tells you what's legal. NIOSH's TWA tells you what's actually safe. The calculator shows both so you can see the gap.

OSHA (29 CFR 1910.95)

Legal compliance

5 dB exchange rate — every 5 dB doubles the allowable exposure time
85 dBA Action Level — triggers hearing conservation program enrollment
90 dBA PEL — mandatory engineering controls and HPD use
Excludes sound levels below 80 dBA from the dose calculation

NIOSH (1998 Criteria)

Hearing health protection

3 dB exchange rate — equal-energy principle, more protective
85 dBA REL — recommended exposure limit with no separate "action level"
Used by most international standards (EU, Canada, Australia, ISO)
For the same noise data, the NIOSH TWA is almost always higher than OSHA's

Free Tools That Pair With This

TWA Tells You the Noise. Now Check Protection & Hearing.

A TWA only tells you the exposure. To close the loop you also need to know whether the HPDs are actually working — and whether the worker's hearing is shifting.

Free Tool

NRR Derating Calculator

Enter the NRR on the earplug or muff box. Get OSHA & NIOSH derated values and protected exposure when paired with this TWA.

Free Tool

OSHA STS Calculator

If TWA is over the Action Level for years, hearing shifts. Calculate Standard Threshold Shift with Appendix F age correction and OSHA 300 recordability.

Take the Next Step on Noise Exposure

Deeper material on continuous monitoring, plus the OSHA features and industry guides that put TWA in context.

How Soundtrace Handles It

Continuous Noise Monitoring

Connected dosimetry calculates each worker's TWA automatically — no manual sampling, no spreadsheets.

OSHA Recordkeeping

Auto-generated 300 logs the moment a recordable hearing-loss case is confirmed.

Audiometric Testing

Boothless OSHA-compliant audiograms tied to each worker's TWA history.

Research & Deep Dives

Silent Liability White Paper

How undocumented noise exposure becomes a workers' comp and litigation problem.

Field Booth Validation Study

Boothless audiometry vs. ANSI booth — accuracy data tied to TWA exposure.

OSHA ITA Hearing-Loss Database

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

Industries Where TWA Often Exceeds 85 dBA

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

Reference & Compliance

OSHA HCP Annual Checklist

Every line item OSHA inspectors verify, including the noise monitoring requirements.

Mobile Hearing Testing

Replace mobile vans with on-site Invisible Booth™ testing tied to each TWA history.

Hearing Conservation FAQ

Quick answers to the most common TWA, monitoring, and HCP questions.

Common Questions

TWA Calculator FAQ

Everything you need to know about the OSHA 8-hour TWA, daily dose, and the difference between OSHA and NIOSH calculations.

TWA is the average noise exposure level a worker experiences over an 8-hour work shift, expressed in A-weighted decibels (dBA). Because real-world noise varies — a worker might be at 92 dBA for two hours and 78 dBA for six — the TWA condenses that variation into a single number that represents what the worker would have experienced if exposed to a constant level for the full 8-hour shift.

Stop calculating TWAs by hand

Soundtrace's connected dosimetry calculates every worker's TWA automatically — every shift, every site — and ties the result directly to their audiometric record. No spreadsheets. No manual math. OSHA-ready records on day one.

See How Continuous Monitoring Works Talk to a CAOHC-certified OHC