Understanding audiogram patterns is essential for EHS managers who review occupational audiometric surveillance results. This guide covers normal hearing thresholds: what it looks like on an audiogram, what it means clinically, what OSHA 1910.95 obligations it triggers, and the required employer response. Note that audiogram interpretation in the context of OSHA compliance always requires involvement of a licensed Professional Supervisor — a licensed audiologist, otolaryngologist, or other physician. The EHS manager's role is to understand the pattern well enough to act appropriately and ensure timely PS review.
Soundtrace provides audiometric testing supervised by a licensed audiologist who reviews all audiograms, identifies STSs, and makes clinical determinations — ensuring employer compliance with every 1910.95 audiometric obligation.
What Is Normal Hearing Thresholds?
Normal hearing thresholds on an occupational audiogram are generally defined as thresholds of 25 dBHL or better across all tested frequencies (500–6000 Hz). A normal audiogram shows all threshold markers at or near the 0–25 dBHL range on the audiogram chart. This is the expected result for a newly hired worker before significant occupational noise exposure begins.
Clinical Significance
A normal audiogram in an enrolled worker confirms that, at the time of testing, the worker has no detectable threshold elevation from noise or other causes. For the employer, this is the most favorable possible audiogram result. For the worker, normal thresholds confirm their hearing is not yet affected by occupational noise exposure. Clinically, normal hearing thresholds do not rule out cochlear synaptopathy (hidden hearing loss) at the microscopic level, but for OSHA compliance purposes, the audiogram reflects functional hearing status.
All clinical interpretations of occupational audiograms — including determinations of audiogram pattern, work-relatedness, and STS confirmation — must be made by the Professional Supervisor (licensed audiologist, otolaryngologist, or other physician) under OSHA 1910.95(g)(3). EHS managers should understand these patterns to recognize when PS review is needed and to act on PS findings promptly, not to replace the PS role.
OSHA 1910.95 Implications
A normal audiogram at baseline creates the reference point against which all future threshold shifts are measured. Its value to the employer is primarily defensive: it proves the worker had normal hearing at hire, making it impossible for future WC claims to attribute hearing loss from prior employment or non-occupational causes to the current employer's noise exposure. See: pre-employment audiogram and WC defense. Workers with normal hearing still must be enrolled in the HCP if their noise exposure meets or exceeds 85 dBA TWA — normal hearing does not remove the OSHA obligation.
Required Employer Response
A normal audiogram taken within 6 months of the worker's first exposure at or above 85 dBA TWA becomes their legal OSHA baseline. Missing this window is the most commonly cited 1910.95 violation.
A normal baseline audiogram is most valuable as a WC defense document years or decades after the worker's employment ends. It must be accessible at claim time.
Annual audiograms are compared to this normal baseline. The earlier you establish a clean normal baseline, the more defensible your STS calculations are when thresholds eventually shift.
Audiologist-supervised audiometric testing with automatic STS detection
Soundtrace audiometric testing is supervised by a licensed audiologist who reviews every audiogram, identifies all STSs, and makes clinical determinations — ensuring your program meets every 1910.95 requirement.
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Normal hearing thresholds on an occupational audiogram are generally defined as thresholds of 25 dBHL or better across all tested frequencies (500–6000 Hz). A normal audiogram shows all threshold markers at or near the 0–25 dBHL range on the audiogram chart. This is the expected result for a newly hired worker before significant occupat
A normal audiogram at baseline creates the reference point against which all future threshold shifts are measured. Its value to the employer is primarily defensive: it proves the worker had normal hearing at hire, making it impossible for future WC claims to attribute hearing loss from prior employm. The Professional Supervisor must review all audiograms with significant findings to determine STS status and work-relatedness.
The Professional Supervisor — a licensed audiologist, otolaryngologist, or other physician — must review any audiogram with clinically significant findings. OSHA 1910.95(g)(3) requires PS involvement in all STS determinations and medical referral decisions. EHS managers should not attempt to interpret audiogram patterns independently.