Baseline revision is indicated under two circumstances: when an STS is deemed persistent after retesting (29 CFR 1910.95(g)(9)(i)), and when an annual audiogram shows significant improvement over the established baseline (29 CFR 1910.95(g)(9)(ii)). The decision is made by the Audiology Reviewer, not the test examiner.
Baseline revision is indicated under two circumstances per OSHA: when an STS is deemed persistent (29 CFR 1910.95(g)(9)(i)) and when the annual audiogram shows significant improvement over the established baseline (29 CFR 1910.95(g)(9)(ii)). In practice, reviewers also consider: whether the current audiogram represents the employee’s true hearing status versus a transient shift; whether prior baseline errors (such as a baseline recorded during a TTS) should be corrected; and whether the pattern of results across multiple years is consistent. The decision to revise a baseline audiogram must be made by a qualified professional — it is a clinical determination, not an automatic rule. An incorrect baseline revision can suppress future STS detection for years.
