Audiometric Testing for Employers: Complete OSHA 1910.95 Guide

Audiometric testing is the systematic measurement of employee hearing thresholds over time — required by OSHA 1910.95(g) for every worker exposed to noise at or above 85 dBA as an 8-hour TWA. The program must include a baseline audiogram, annual audiograms compared to that baseline, Standard Threshold Shift detection with required follow-up, and lifelong record retention. Understanding each requirement — and the compliance gaps that generate citations — is the foundation of a defensible hearing conservation program.

Soundtrace audiometric testing automates the full cycle: baseline and annual scheduling, Type 4 microprocessor audiometry with per-test ambient noise validation, STS detection and 21-day notification workflows, and 30-year cloud retention — all supervised by a licensed audiologist.

What Is Audiometric Testing?

Audiometric testing is a structured process that measures an individual's hearing sensitivity at specific frequencies — the softest tones detectable at each pitch. In occupational health, it serves a distinct purpose from clinical audiology: rather than diagnosing hearing disorders, occupational audiometric testing creates a longitudinal record of each worker's hearing thresholds so that changes attributable to workplace noise exposure can be detected, documented, and acted on.

An occupational audiogram tests pure-tone hearing thresholds at 500, 1000, 2000, 3000, 4000, and 6000 Hz in each ear. Results are plotted on a standardized chart. The employer — not the worker — is responsible for providing testing, retaining results, comparing annual tests to the baseline, detecting shifts, and following through on required actions. The CDC estimates 22 million U.S. workers are exposed to hazardous occupational noise annually; audiometric testing is the mechanism that turns that exposure into an actionable compliance and defense record.

Who Must Provide Audiometric Testing

The obligation to provide audiometric testing attaches to the employee’s noise exposure level, not to the industry or job title. Any employee whose TWA exposure equals or exceeds 85 dBA must be enrolled in the hearing conservation program and provided audiometric testing. This threshold is determined by noise monitoring under 1910.95(d).

The employer must provide audiometric testing at no cost to the employee, at a reasonable time and place. Testing conducted outside of normal work hours must be compensated. Self-referral by an employee does not satisfy the employer’s obligation — the program must be employer-administered and documented.

Baseline Audiogram Requirements

The baseline audiogram establishes the reference point against which all future audiograms are compared for STS detection. It must be obtained within six months of the employee first being exposed at or above the action level, and it must be preceded by at least 14 hours of quiet. The 14-hour requirement protects against temporary threshold shift (TTS) contaminating the baseline.

Employers using mobile test vans have 12 months instead of 6 months to establish a baseline, but must provide hearing protectors to enrolled employees during the gap. The baseline may be revised: if a subsequent audiogram shows better thresholds, the better audiogram becomes the new baseline. The Professional Supervisor may also revise a baseline if it was invalid due to TTS, calibration error, or equipment failure.

Annual Audiogram Requirements

Every enrolled employee must receive an annual audiogram within 12 months of their previous audiogram. The 12-month interval is measured from audiogram to audiogram — not from enrollment date or calendar year. At facilities using an annual mobile van visit, employees tested in different months will have different compliance deadlines, and the employer is responsible for tracking each employee’s individual expiration date.

Frequencies Tested and the STS Calculation

The annual audiogram must test at 500, 1000, 2000, 3000, 4000, and 6000 Hz in each ear. The STS determination uses the average of only 2000, 3000, and 4000 Hz, but the full frequency range must be tested and recorded. The 4000 Hz notch is the audiometric signature of noise-induced hearing loss. See: noise-induced hearing loss: the complete employer guide.

Equipment and Calibration Standards

Audiometers used for occupational audiometric testing must meet ANSI S3.6 specifications. Three levels of calibration are required:

• Daily acoustical check (biological check): Before each use, the audiometer must be checked against a person with a known, stable audiogram. Any shift of 10 dB or more at any test frequency must be investigated before testing continues.
• Annual calibration: A formal calibration by a qualified technician checking output levels, frequency accuracy, attenuator linearity, and signal purity. Required at least annually or after any repair or modification.
• Biennial electroacoustic calibration: A comprehensive calibration per ANSI S3.6 required at least every two years.

Ambient Noise and Boothless Audiometry

The test environment must meet the maximum permissible ambient noise levels from ANSI S3.1 (Table D-1 in Appendix D to 1910.95). Testing in spaces that exceed these limits produces audiograms that are not valid for compliance purposes because background noise can mask tones and cause apparent threshold elevation. See: ambient noise compliance and audiometric testing protocol.

Standard Threshold Shift: Detection and Response

A Standard Threshold Shift (STS) is defined as 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 detection is the core clinical function of the audiometric program — it triggers a required chain of employer actions and, depending on severity, a 1904.10 recordkeeping entry. See: OSHA 300 log hearing loss recordkeeping rules.

Age correction is optional but commonly applied. If the age-corrected shift is still 10 dB or greater, the STS stands. If the age correction reduces the shift below 10 dB, no STS exists — but the audiogram and the calculation must be documented. See: OSHA audiogram age correction: Appendix F guide.

How to Read an Audiogram

An audiogram plots hearing thresholds in decibels hearing level (dBHL) against frequency. The y-axis is inverted: lower numbers (better hearing) appear at the top, higher numbers (worse hearing) at the bottom. Normal hearing for occupational purposes is generally 25 dBHL or below across all tested frequencies. The characteristic NIHL signature is a notch at 4000 Hz that typically extends to 3000 Hz with continued exposure.

Onsite, Mobile, and In-House Audiometric Testing Options

Employers have three practical delivery models for occupational audiometric testing. The right choice depends on workforce size, shift patterns, facility layout, and risk tolerance for compliance gaps.

Onsite audiometric testing uses equipment installed at or brought to the employer’s facility, allowing workers to be tested on any shift without leaving the site. Onsite testing gives employers the most scheduling control, eliminates the 12-month mobile van baseline window, and keeps audiometric records within the employer’s own system. It is the model best suited to multi-shift facilities and employers who have experienced compliance gaps from annual van visit scheduling.

Mobile audiometric testing uses a vendor-operated van that visits the facility on a scheduled basis — typically once a year. The van model requires no capital investment but creates several risk points: employees tested in different months have different compliance deadlines; van visits can be delayed or cancelled; and records are often retained by the vendor, creating access risk if the vendor changes ownership or closes. Employers using mobile testing must ensure they can independently access all audiometric records at any time.

7 Most Common Audiometric Testing Compliance Mistakes

1. Missing or late baseline audiogram: New hire tested at month 7 instead of month 6 — the most commonly cited audiometric violation. No system to track the 6-month deadline per employee.
2. Baseline contaminated by TTS: Worker tested immediately after a noise-exposed shift instead of the required 14-hour quiet period. Results in an artificially elevated baseline that reduces future STS sensitivity.
3. STS not identified: Annual audiograms filed without systematic comparison to the baseline. The comparison is done visually or not at all — STSs go undetected.
4. 21-day notification missed: STS identified but the written notification to the employee is late or never sent. This is a separate citable violation from the STS itself.
5. Test environment not validated: Audiograms conducted in spaces where ambient noise was never measured. If ANSI S3.1 limits were exceeded, those audiograms are not valid.
6. Mobile van records inaccessible: Vendor retains records. Vendor is acquired, closes, or loses data. Employer cannot produce audiometric history for WC defense or OSHA inspection.
7. Only tracking calendar-year testing: Employees added mid-year have different 12-month deadlines. Testing only in January leaves mid-year hires out of cycle.

Frequently Asked Questions