Air conduction thresholds at 500, 1000, 2000, 3000, 4000 and 6000 Hz in each ear - the frequencies OSHA requires. The quietest level a person reliably detects at each frequency is their threshold. Noise-induced loss characteristically…
Air conduction thresholds at 500, 1000, 2000, 3000, 4000 and 6000 Hz in each ear - the frequencies OSHA requires. The quietest level a person reliably detects at each frequency is their threshold. Noise-induced loss characteristically appears first as a notch around 3000 to 6000 Hz, which is why those frequencies carry the weight in shift calculations.
A functional check before each day of testing: listening checks and biological verification. An acoustic calibration annually. An exhaustive calibration every two years. Audiograms produced on equipment outside its calibration interval are not defensible, and we carry the certificates rather than asserting compliance.
The standard sets maximum permissible ambient sound pressure levels in the test space per frequency. We verify with a sound level meter before the first test. If your yard is too loud where we are parked, we move - a test run in excessive ambient noise produces elevated thresholds that look like hearing loss and are an artefact of the room.
Apparent shifts are common and frequently temporary: a noisy commute, a head cold, wax, or simply a poor first attempt at an unfamiliar task. The standard permits a retest within 30 days before confirming a standard threshold shift, and a meaningful share resolve. Confirming without retesting generates paperwork, worry and referrals that were never needed.
Primary regulations and standards referenced above. Where a standard is published commercially it is named in full rather than linked to a copy.