Audiometer Calibration Service: NIST-Traceable, Mail-In or On-Site

What audiometer calibration is

An audiometer is only useful if the tones it presents are the tones it claims to present. Calibration compares the instrument's actual output against a reference standard and corrects or documents any difference. For pure-tone audiometers, that reference is ANSI S3.6, the American National Standard specification for audiometers.

Every Foster calibration is performed against NIST-traceable reference equipment, and the unit comes back with a traceable calibration certificate for your records. Foster uses industry-standard ACS hardware and software on the bench, so results are consistent from one unit to the next.

We calibrate the instruments we sell and most major brands, whether or not you bought from us. That includes Benson, Tremetrics, Maico, GSI, and Welch Allyn / Hill-Rom microprocessor audiometers.

What the OSHA hearing conservation standard requires

OSHA 29 CFR 1910.95(h) requires audiometric tests to be run on audiometers that meet ANSI S3.6 and are maintained and used in accordance with it. The rule sets three layers of checking.

• A functional check before each day's use, by testing a person with known, stable hearing thresholds and listening to the output for distortion or unwanted sounds. A deviation of 10 dB or more calls for an acoustic calibration.
• An acoustic calibration check at least annually, following Appendix E of the standard. A deviation of 15 dB or more calls for an exhaustive calibration.
• An exhaustive calibration at least every two years, covering the S3.6 sections that the standard lists.

29 CFR 1910.95(h), Appendix E

Annual calibration is the program's anchor

OSHA 1910.95 requires annual acoustic calibration, and most hearing conservation programs build their yearly cycle around it. When an auditor or compliance officer reviews your records, a current certificate for the audiometer that produced each audiogram is the first thing they look for. A lapsed certificate puts every test taken since the due date in question.

That is why Foster tracks your due dates and sends a reminder ahead of the next one. The goal is that calibration never becomes a scramble.

What we check

Calibration is a set of measurements, not a single pass or fail. On a typical audiometer, the bench work covers the following.

• Output levels. Sound pressure level at each test frequency through the earphones, measured in a standard coupler and compared with the S3.6 reference levels.
• Frequency accuracy. Whether each tone is the frequency the dial says it is.
• Distortion. Harmonic distortion in the output, since a distorted tone can give a false threshold.
• Attenuator linearity. Whether a 5 dB step on the dial is a 5 dB step in the output, across the range you use.
• Bone conduction. Output through the bone vibrator, measured on a mechanical coupler, where the audiometer has that function.
• Masking. Level and accuracy of the masking noise used in the opposite ear.
• Tone presentation and controls. Rise and fall behavior of the tone, the hand switch, cords, and connectors.

Mail-in or on-site

Mail-in is the simplest path for a single unit or a small group. You ship the audiometer, we calibrate and return it, and nothing about your site has to change. Mail-in calibration is available nationwide.

On-site calibration suits larger fleets and anyone who cannot be without the unit. A technician comes to your facility and can calibrate several instruments in one visit. Booth sound-level checks can be done during the same visit. On-site service is regular across the Ohio Valley and available nationwide, so ask about your location.

We also accept drop-off at our Cincinnati facility if you are local.

How mail-in calibration works

• Tell us what you run. Send the make, model, and number of units, and where they live.
• We schedule the service and send simple packing and shipping instructions.
• Pack the audiometer with its transducers and cords and ship it to our Cincinnati facility.
• Our bench technicians calibrate it, repair anything that is out of specification, and return it.
• You receive a traceable calibration certificate for your OSHA records, plus a reminder before the next due date.

Turnaround, repairs, and loaners

Bench turnaround is fast, and we will confirm timing with you when you request service. Routine calibrations move quickly. If the audiometer needs an extensive repair, the timeline depends on the repair, and we will tell you what we find.

When you calibrate with Foster, you get access to our free loaner instruments if your unit requires extensive repairs. Your testing keeps running while we fix it.

What you get back

Each unit returns with a calibration certificate that is NIST-traceable and calibrated to ANSI S3.6. If the audiometer is also used in a booth or quiet room, the certificate can carry a Room Acoustics Level Test section. See our page on sound booth testing for how that works.

Who sends us audiometers

Our calibration customers include manufacturers and other employers with in-house hearing conservation programs, occupational health clinics, schools running screening programs, and mobile testing providers. A single booth audiometer and a fleet of portable units follow the same process. If you are not sure which of your instruments are due, send us the list and we will help sort it out.

Why employers choose Foster

Foster runs hearing conservation programs, sells audiometers, trains technicians, and calibrates instruments, so we see the whole chain from the calibration certificate to the audiogram. Calibration is compliance-driven work, and we treat it that way: clear paperwork, due-date tracking, and a person you can call at 513-891-0868 when a unit is down.