Does My Equipment Need Annual Calibration?

What's happening

OSHA's occupational noise standard, 29 CFR 1910.95, requires an audiometer used for hearing testing to receive an exhaustive calibration at least once a year, along with a documented daily biological or acoustic check before use each day. Those are two different things doing two different jobs, and it's easy to assume that if the daily check passed, the equipment is fine for the year. It isn't — and the same question comes up about the sound level meter and the acoustic calibrator, which aren't audiometers but are just as central to a valid test.

The daily check versus the annual calibration

The daily check is quick, and it's meant to be: it confirms the audiometer is producing tones and reading responses roughly where it should be, first thing each testing day. It does not replace the annual calibration. It can't catch slow drift in the output level at specific frequencies, and it isn't a substitute for having the full signal chain measured and adjusted against a traceable standard.

The annual exhaustive calibration is the deeper check — it verifies the audiometer's output across the full range of frequencies and levels it's rated for, not just the handful the daily check touches. That's the one OSHA requires yearly, and it's the one that needs to be performed by someone with the right measurement equipment, not done in the field.

Which items need annual calibration

Item	Annual calibration needed	Notes
Audiometer	Yes — OSHA-required	Exhaustive calibration, once per year, plus the required daily check
Booth sound level meter / acoustic calibrator	Yes — Foster standard	Not always spelled out as a hard OSHA deadline for the meter itself, but the microphone and measurement chain drift with age and everyday handling. Annual matches most service schedules and general noise-measurement practice, and it's what we recommend.
Noise dosimeter	Not through Foster	See below

Foster does not calibrate noise dosimeters

This is worth stating plainly because it's a common point of confusion: Foster calibrates sound level meters and audiometers, but we do not provide calibration for noise dosimeters. If you've had a sound level meter serviced and are expecting a separate dosimeter certificate, it won't be included — that service only covers the meter. If you need a dosimeter formally calibrated, that has to go through a lab that specifically offers dosimeter calibration.

Before you send a dosimeter out or assume it needs service, check the simple thing first: a dosimeter reading out of tolerance is very often just low batteries. Swap the batteries and re-check before treating it as a calibration problem — this alone resolves it more often than not.

When to call us

• You're not sure when your audiometer's or sound level meter's annual calibration is due.
• Your daily check has been passing but you want to confirm your annual calibration schedule is current.
• You need a dosimeter calibrated — we can point you toward the right kind of provider, even though we don't perform that service ourselves.