Share article
Audiometric testing is the clinical core of every OSHA hearing conservation program. Under 29 CFR 1910.95(g), general industry employers must provide a baseline audiogram within 6 months of an employee’s first noise exposure at or above 85 dBA TWA, followed by annual audiograms every 12 months. This guide covers every requirement—testing frequency, equipment standards, standard threshold shift (STS) identification and response, in-house vs. mobile van decisions, and the documentation employers need to survive an inspection.
Soundtrace is a digital hearing conservation platform offering boothless in-house audiometric testing, automatic STS flagging, ANSI S3.6-compliant audiometers, and cloud recordkeeping—purpose-built for industrial safety programs.
Under 29 CFR 1910.95(g)(1), audiometric testing must be made available to all employees whose noise exposure equals or exceeds an 8-hour TWA of 85 dBA—OSHA’s action level. The program must be provided at no cost to employees, at a time that does not require them to travel on their own time.
| Worker Category | Testing Required? | Governing Standard |
|---|---|---|
| General industry at or above 85 dBA TWA | Yes — baseline + annual | 29 CFR 1910.95(g) |
| General industry below 85 dBA TWA | No (voluntary only) | 29 CFR 1910.95 |
| Construction worker | Not mandated under 1926.52 | 29 CFR 1926.52 |
| Mining worker | Yes — under MSHA rules | 30 CFR Parts 56/57/62 |
Press lines, stamping, machining, and assembly operations routinely exceed 85 dBA. Full enrollment required for these job classifications.
Filling lines, conveyors, and industrial chillers. Workers in these areas frequently hit the action level during a standard 8-hour shift.
Air tools, robotic welding, and stamping presses. Most production-floor workers in auto plants are enrolled in HCPs.
Compressors, generators, and pump stations. Shift workers at these facilities often accumulate significant daily noise dose.
Any employee whose noise exposure equals or exceeds 85 dBA TWA must be enrolled in audiometric testing. Enrollment is by job classification, not by individual self-report.
The baseline audiogram is the reference against which every future annual audiogram is compared. Getting it right—and getting it on time—is the single most important act in an audiometric program. A flawed or late baseline creates cascading compliance problems for the entire duration of employment.
Under 1910.95(g)(5), the baseline must be provided within 6 months of first noise exposure at or above the action level. If testing relies on a mobile audiometry van, the deadline extends to 12 months—but the employee must wear hearing protection during the entire interim period.
Before taking a baseline audiogram, the employee must have at least 14 hours free from workplace noise exposure. Employers may use hearing protectors as a substitute for this quiet period, but must document that HPDs were worn during any noise exposure in the 14 hours prior to the test.
The audiometer must test 500, 1000, 2000, 3000, 4000, and 6000 Hz per ear. Results at 2000, 3000, and 4000 Hz are the STS calculation frequencies. All six must be documented in the record.
The baseline audiogram must be accessible for every future STS calculation for as long as the employee works in a noise-exposed role. Digital records with direct linkage to subsequent audiograms are the only reliable way to maintain this over multi-year employment.
Testing new hires at their 90-day review or first annual audit instead of within the 6-month window. At high-turnover facilities, this creates a permanent backlog of employees without valid baselines. Without a baseline, you cannot calculate an STS—meaning every subsequent annual audiogram is compliance-worthless for STS purposes and represents open OSHA liability.
Related: Baseline Audiogram Testing During Onboarding · Baseline vs. Annual Audiogram: What’s the Difference?
The baseline audiogram is the most important audiogram in an employee’s file. A late or invalid baseline makes every subsequent annual audiogram useless for STS calculation—the entire clinical purpose of the program.
After the baseline is established, 1910.95(g)(6) requires an annual audiogram at least once every 12 months for all enrolled employees. There is no grace period. An employee tested in March must be retested by March the following year.
Relying on a mobile van schedule that slips by weeks or months each year. After a few cycles, the “annual” audiogram has drifted to 15–18 months from the last one. OSHA inspectors look at the dates on file and will cite gaps over 12 months as a violation of 1910.95(g)(6). In-house testing with a fixed calendar eliminates drift entirely.
Related: How Often Is Audiometric Testing Required by OSHA? · Audiometric Testing Frequency: Employer Guide
Annual means annual. A testing schedule that drifts even a few weeks each year will eventually produce a gap that constitutes an OSHA citation.
OSHA 1910.95(h) specifies that audiometric test equipment must meet ANSI S3.6 (Standard Specification for Audiometers). This means a pure-tone, air-conduction audiometer capable of testing all six required frequencies at the required intensity levels. Two required calibration types apply:
A trained person listens to the audiometer output and verifies it sounds correct at each frequency. Must be logged. Most commonly skipped—and most commonly cited.
Output levels at each frequency verified using a sound level meter and coupler. Conducted by qualified technician. Any deviation >15 dB triggers exhaustive calibration.
Full bench calibration by audiometer service technician. Required if acoustic calibration fails, if the audiometer is repaired, or as preventive maintenance every 2 years.
Performing the annual acoustic calibration but treating the daily biological check as optional. OSHA inspectors ask for calibration logs and will cite missing daily check records. An audiometer that malfunctions mid-week without a documented daily check also invalidates all audiograms taken since the last logged calibration—potentially months of data.
Full equipment guide: Audiometric Testing Equipment: What OSHA Requires
Calibration records are not optional documentation—they are a required element of every audiometric record under 1910.95(m)(2)(i)(C). Missing calibration logs can invalidate years of audiometric data in a single inspection.
The standard threshold shift is the clinical trigger that separates a routine annual audiogram from an OSHA-reportable event. Under 1910.95(f), an 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.
Annual audiogram shows ≥10 dB average shift at 2000 + 3000 + 4000 Hz in either ear vs. baseline
Obtain a retest within 30 days unless a licensed audiologist or physician confirms the shift without retesting
Written notification required. Employee must be informed of the confirmed STS and its implications
Employer must refit or retrain the employee on hearing protection devices—current device may be inadequate
If hearing loss appears not work-related, refer to audiologist, otolaryngologist, or physician for evaluation
Record if confirmed shift + age correction results in average hearing level ≥25 dB HL at STS frequencies
If audiologist or physician determines STS is persistent, the new audiogram becomes the revised baseline for future comparisons
Using paper-based systems where no one actually compares baseline to annual audiograms year over year. With paper files, STS detection requires a human to pull two physical files, do arithmetic at 2000, 3000, and 4000 Hz for both ears, and log the result. This rarely happens consistently—meaning STSs go undetected, unreported, and unresponded to. Employers can face citations not just for the missed STS but for failing to notify, failing to refit, and failing to make the 300 log entry.
Full STS guides: STS: OSHA Definition, Calculation, and Employer Action · STS: The Complete Employer Action Guide · OSHA 300 Log Hearing Loss Recordability
Automated STS detection eliminates the manual comparison step and flags every confirmed shift immediately—removing the single most common source of STS-related OSHA citations.
An audiogram plots a person’s hearing thresholds against frequency. The horizontal axis shows frequency in Hz (low to high); the vertical axis shows hearing level in dB HL (louder sounds needed to hear moving downward). Normal hearing is 0–25 dB HL. Results at each frequency are marked with O (right ear) and X (left ear).
Hearing Level Classification — HCP Implications
Shape: Sharp notch at 4000 Hz, often recovering slightly at 6000 Hz
Onset: Gradual over years; worker often unaware until significant loss has accumulated
OSHA relevance: Strong indicator that noise exposure is the cause. STS calculation targets 2000–4000 Hz specifically because this is the NIHL zone.
Action: Review HPD program adequacy; consider fit testing; reassess noise monitoring
Shape: Gradual high-frequency slope, no sharp notch; symmetric across both ears
Onset: Progressive with age; typically begins affecting frequencies above 4000 Hz first
OSHA relevance: Age correction from Appendix F to 1910.95 can be applied to STS calculations to distinguish age-related from noise-induced change
Action: Apply age correction before OSHA 300 log determination; still monitor annually
Audiogram reading guides: How to Read an Audiogram: Plain-English Guide for Safety Managers · What Is an Audiogram?
The most consequential operational decision in an audiometric program is whether to test in-house or outsource to a mobile audiometry van. Both are OSHA-compliant when properly implemented, but they differ significantly across every dimension that matters for program quality.
| Factor | Mobile Van | In-House (Digital) |
|---|---|---|
| Upfront cost | None | Equipment investment required |
| Per-employee annual cost | $80–$150 | $20–$60 at scale |
| Scheduling flexibility | Low — van availability dictates schedule | High — test any time |
| STS detection speed | Weeks to months (vendor report cycle) | Real-time — flagged immediately |
| Record portability | Often siloed with vendor | Employer-owned cloud records |
| Baseline timing control | Limited by van schedule | Test within days of hire |
| Calibration documentation | Vendor-managed; hard to audit | Stored per-device in your system |
Annual Cost per Employee by Testing Model
Assuming the mobile van vendor is handling STS detection and 300 log notification. Most mobile van vendors provide raw audiogram data only. STS calculation, 300 log determination, employee notification, and follow-up action are the employer’s responsibility under 1910.95—not the vendor’s. Employers who receive a box of audiogram printouts each year and file them without review are not meeting their OSHA obligations, regardless of who conducted the test.
Full comparison: In-House vs. Mobile Van: Cost Comparison · Mobile Van vs. In-House: Objective Comparison · The Hidden Costs of Mobile Van Testing
Switching from mobile van to in-house testing typically cuts per-employee cost by 40–60% within the first year and eliminates scheduling bottlenecks that cause late baselines and missed annual windows.
Traditional audiometric testing required a sound-attenuating booth. Boothless audiometry uses insert earphones with high passive attenuation to block ambient noise, enabling OSHA-compliant testing outside a booth when ambient sound levels are within acceptable limits set in Appendix D to 1910.95.
OSHA does not require a booth—it requires that the test environment meet maximum permissible ambient noise levels from Table D-1 of Appendix D. Modern boothless systems using insert earphones (NRR 28+) can meet these thresholds in most standard break rooms, offices, or conference rooms. The insert earphone blocks ambient sound before it reaches the ear canal, allowing accurate threshold measurement without acoustic isolation of the room itself.
Conducting boothless testing in an environment that is too loud without measuring ambient noise first. If the testing area exceeds maximum permissible background levels in Appendix D, the audiograms produced are not OSHA-compliant—even if they look reasonable. This is particularly common near production floors or in busy break areas. Always verify ambient noise in the testing room before using it for audiometry.
Related: Bringing Audiometry Testing In-House: What You Need to Know · Boothless Audiometry: OSHA Compliance Requirements
Under 1910.95(m)(2), employers must retain audiometric test records for the duration of the affected employee’s employment. A complete audiometric record is not just the hearing threshold data—it is the data plus calibration documentation, ambient noise levels, and the employee’s most recent noise exposure assessment, all linked and retained together.
| Required Element | Retention Period | Why It Matters |
|---|---|---|
| Employee audiogram results | Duration of employment | Baseline required for all future STS calculations |
| Audiometer serial number & calibration date | Duration of employment | Validates that audiometer was compliant when test was conducted |
| Test room background sound levels | Duration of employment | Confirms Appendix D compliance for each test session |
| Employee’s most recent noise exposure assessment | Duration of employment | Required element linking exposure to audiogram record |
| Examiner name, credentials, supervising professional | Duration of employment | Validates that testing was conducted by qualified person per 1910.95(g)(3) |
| Noise exposure measurements | 2 years | Documents which employees required enrollment |
Retaining audiograms but not the supporting calibration and noise exposure data. OSHA’s recordkeeping requirement encompasses more than the audiogram results. An audiogram record missing calibration date, test room levels, or noise exposure linkage is technically incomplete and can be cited. Paper-based systems rarely maintain these linkages reliably across years of records.
Related: OSHA Hearing Conservation Recordkeeping: What to Keep and for How Long · Managing a Hearing Conservation Program Across Multiple Sites
Testing at the 90-day review or first annual audit instead of within 6 months. Without a valid baseline, every subsequent audiogram is useless for STS calculation. Applies especially at high-turnover facilities. OSHA section: 1910.95(g)(5)
Relying on a mobile van that slips 4–6 weeks each year. After 2–3 cycles, the gap exceeds 12 months and becomes a citable violation. Fixed in-house scheduling eliminates this entirely. OSHA section: 1910.95(g)(6)
Annual acoustic calibration performed, but daily biological checks not logged. Both are required. Missing daily logs can invalidate all audiograms taken since the last entry. OSHA section: 1910.95(h) and 1910.95(m)(2)
With paper files, STS detection requires a human to manually compare two records and do arithmetic. This rarely happens consistently at scale. Automated STS flagging eliminates this risk entirely. OSHA section: 1910.95(g)(8)
Mobile van vendors provide data. STS calculation, 300 log determination, employee notification, HPD refit, and referral are all the employer’s responsibility under 1910.95. The vendor has no OSHA obligation. OSHA section: 1910.95(f)
Conducting boothless audiometry without first verifying ambient noise levels meet Appendix D limits. Audiograms from a non-compliant environment are invalid—and may appear normal even when hearing loss is present. OSHA section: Appendix D, 1910.95
Retaining audiogram results but not the linked calibration records, ambient noise documentation, and noise exposure assessments required by 1910.95(m)(2). A partial record is a citable record. OSHA section: 1910.95(m)(2)
The financial case for in-house audiometric testing is strongest at facilities with 50+ enrolled employees, high turnover, or multi-site programs where record portability is a persistent challenge.
In-house platforms cost $20–$60 per employee annually vs. $80–$150 for mobile van. Facilities with 200+ employees typically break even in Year 1.
Serious violations can reach $16,550 per violation per day. A missed STS that triggers a citation across 50 employees is a significant financial event.
Occupational hearing loss claims average $24,000 each. Earlier STS detection enables intervention before permanent threshold shifts become recordable and compensable.
Digital platforms eliminate manual comparison, paper filing, and report interpretation time—freeing EHS staff for other compliance priorities.
Related: ROI of Hearing Conservation: How to Make the Business Case · How Much Does a Hearing Conservation Program Cost Per Employee? · The ROI of In-House Testing
Soundtrace handles baseline scheduling, automated STS detection, calibration logging, and cloud recordkeeping—ANSI S3.6-compliant, fully integrated with your entire HCP.
Book a DemoGet a quote for your facility →Under 29 CFR 1910.95(g)(5), a baseline audiogram must be provided within 6 months of the employee’s first exposure at or above the 85 dBA action level. If a mobile audiometry van is used, the deadline extends to 12 months, provided the employee wears hearing protection during the interim period. The employee must also have 14 hours free from workplace noise before the baseline test.
Under 29 CFR 1910.95(g)(6), annual audiograms must be conducted at least once every 12 months for all enrolled employees. There is no grace period. An employee tested in March must be retested by March the following year. Gaps beyond 12 months constitute a violation of the annual testing requirement.
Under 29 CFR 1910.95(f), an STS is a change in hearing threshold, relative to the baseline audiogram, averaging 10 dB or more at 2000, 3000, and 4000 Hz in either ear. When an STS is identified, the employer must retest within 30 days if not confirmed, notify the employee in writing within 21 days of confirmation, refit hearing protection, and determine whether the STS is recordable on the OSHA 300 log.
OSHA 1910.95(h) requires audiometers meeting ANSI S3.6 specifications with acoustic calibration at least annually. A biological calibration (listening check) must be performed before each day of use. If acoustic calibration reveals a deviation of more than plus or minus 15 dB at any frequency, or if the audiometer is repaired, an exhaustive calibration by a service technician is required. All calibration records must be retained as part of the audiometric record.
Yes. OSHA does not require a sound booth. It requires that the test environment meet the maximum permissible ambient noise levels in Appendix D to 1910.95. Modern audiometric systems using insert earphones with high passive attenuation can meet these requirements in standard rooms outside a booth. The employer must verify ambient noise levels in the test area before conducting testing.
Under 29 CFR 1910.95(g)(3), audiometric tests must be conducted by a licensed or certified audiologist, otolaryngologist, or physician, or by a technician who is certified by the Council for Accreditation in Occupational Hearing Conservation (CAOHC) or who has satisfactorily demonstrated competence in administering audiometric examinations. The supervising professional must be a licensed or certified audiologist or physician.