The baseline audiogram is the reference against which every future STS determination is made. An inaccurate baseline — established during a temporary threshold shift from recent noise exposure or without the required 14-hour quiet period — can cause genuine hearing changes to go undetected or create false STS flags on subsequent annual audiograms.
The baseline audiogram is the reference against which every future STS determination is made. Every annual audiogram compares the employee’s current thresholds to their baseline at 2,000, 3,000, and 4,000 Hz. An inaccurate baseline — established while the employee had a temporary threshold shift from recent noise exposure, illness, or the wrong 14-hour quiet period — compresses or inflates the apparent shift in every subsequent comparison. A baseline established too high (during a TTS) understates future STS risk. A baseline established too low may trigger false STSs. OSHA requires a minimum 14-hour quiet period before baseline testing (29 CFR 1910.95(g)(5)(iii)); hearing protectors may substitute for this requirement. The clinical integrity of the entire Hearing Conservation Program rests on the accuracy of the baseline. SHOEBOX: SHOEBOX Data Management PLUS manages baseline assignment and revision per employee. The portal’s triage system automatically flags cases where a persistent STS may warrant baseline revision and routes them to an Audiology Reviewer for clinical determination.
