Choosing a Mobile Hearing Testing Vendor: A Compliance Checklist

A safety manager comparing mobile hearing testing vendors usually gets quotes that look nearly identical: a price per employee, a van on-site date, and a promise of "OSHA-compliant" testing. The quote rarely says who performs the test, how the audiometer was last calibrated, or how fast the results reach the person who has to act on a shift. Those details decide whether the program survives an audit, not the price per head.

Foster Special Instruments runs mobile hearing testing across Ohio, Kentucky, and Indiana, and we get asked "what should we be checking before we sign" often enough that it's worth writing down. The answer is the same five items every time: technician credentials, equipment calibration records, the test environment, the data pipeline back to the employer, and who actually reviews a shift.

What credential should the technician have?

29 CFR 1910.95(g)(3) lets an employer use a technician who is certified by the Council for Accreditation in Occupational Hearing Conservation (CAOHC), or one who has demonstrated competence in administering audiometric exams and operates under the supervision of an audiologist, otolaryngologist, or physician. OSHA does not mandate the CAOHC credential by name in the federal text, but it is the de facto proof of training that most employers ask for, and some states require it outright: Oregon and Washington require CAOHC certification for anyone administering a workplace hearing test, and Texas requires technician registration. Ask the vendor for the technician's current CAOHC card (it expires every five years) and ask who the supervising professional is if the technician is working on demonstrated competence instead.

How is the audiometer's calibration documented?

A mobile unit's audiometer needs a functional (daily) check and a periodic exhaustive calibration against ANSI S3.6, same as a fixed-booth instrument. Ask for the calibration certificate on the specific unit that will show up, not a generic fleet statement, and check the date against the manufacturer's recommended interval. An audiometer that has not been recalibrated on schedule produces results that will not hold up if an employee disputes a standard threshold shift finding later.

Does the test environment meet ANSI S3.1, booth or not?

OSHA does not require a soundproof booth. It requires that background noise levels in the octave bands used for testing stay under the limits in 1910.95 Appendix D, measured in the room or vehicle where testing actually happens. A vendor testing in an open warehouse corner without measuring ambient noise is a liability, whether or not they own a booth. Ask whether the vendor measures and documents ambient noise at each site, and what they do when a location fails that check (reschedule, relocate, or use a sound-attenuating booth brought along for the day).

How fast do results come back, and in what format?

A completed audiogram that sits in a vendor's system for three weeks does not help a safety manager who needs to know about a standard threshold shift before the employee's next noisy shift. Ask for a written turnaround commitment and ask to see a sample report: does it flag STS and recordable cases explicitly, or does it hand over raw numbers and expect the employer to do the math? Vendors vary widely here, and the format difference is the gap between a program that catches problems early and one that discovers them at the next OSHA inspection.

Checklist item	What to ask for	Why it matters
Technician credential	Current CAOHC card or named supervising professional	1910.95(g)(3) compliance; some states require it by law
Audiometer calibration	Exhaustive calibration certificate for the specific unit	Defensibility if a threshold shift is disputed
Test environment	Documented ambient noise measurement per Appendix D	Booth is not required, compliance with noise limits is
Results turnaround	Written SLA and a sample flagged report	STS and recordable flags need to reach you before the next shift
Baseline handling	Process for new hires and prior baseline transfer	A missed or late baseline invalidates future shift comparisons

Who owns the baseline, and what happens with new hires?

OSHA's long-standing position, affirmed in a 1984 standard interpretation on mobile testing specifically, is that the baseline-audiogram deadline applies the same way whether testing happens in a fixed booth or a mobile van: signing a vendor contract before the deadline does not satisfy the requirement, the baseline test itself has to happen. New employees get up to one year to establish a valid baseline if logistics require it, but they must wear hearing protection for any exposure above the action level in the meantime. Ask how the vendor tracks new-hire baseline windows across multiple visit dates, not just the annual retest list.

How Foster handles this

Every Foster mobile hearing test is run by a CAOHC-certified or demonstrated-competence technician under our review process, on an audiometer carrying a current ANSI S3.6 calibration certificate, with ambient noise verified at each site per Appendix D before testing starts. Results come back with STS and OSHA-recordable cases flagged explicitly, and new-hire baselines are tracked separately from the annual retest schedule so nobody falls outside the one-year window. For employers juggling that schedule across audiometric, fit testing, and BAT training renewal dates on different clocks, Foster's compliance workspace product tracks each employee against the applicable rule and due date in one view rather than three spreadsheets.

Related reading: see our mobile audiometric testing equipment checklist for what should be on the van itself, and our note on results review and notification timelines for what a good turnaround SLA looks like in practice. Foster also runs on-site occupational health testing that combines hearing, spirometry, and fit testing in one visit; request a quote for your site.

FAQ

Does OSHA require a sound-isolating booth for mobile hearing tests?

No. OSHA's hearing conservation standard sets maximum permissible ambient noise levels for the test room in Appendix D of 29 CFR 1910.95, not a booth requirement. A vendor can test in an open room or vehicle as long as they measure and document that ambient noise stays under those limits.

Is CAOHC certification legally required for a hearing test technician?

Federally, no. OSHA accepts a CAOHC-certified technician or one who has demonstrated competence and works under an audiologist, otolaryngologist, or physician. Some states, including Oregon and Washington, require CAOHC certification by state rule, and Texas requires technician registration.

Can we sign a vendor contract to cover a baseline-audiogram deadline that's about to pass?

No. OSHA has stated in a standard interpretation that a signed contract before the deadline does not satisfy the baseline requirement; the test itself must occur. Employees without a completed baseline must use hearing protection for qualifying noise exposure in the meantime.

How often should the mobile unit's audiometer be recalibrated?

Per the manufacturer's recommended interval, verified against ANSI S3.6, with a daily functional check before each day of testing. Ask any vendor for the current exhaustive calibration certificate on the specific unit being deployed to your site.

Sources

• 29 CFR 1910.95 - Occupational noise exposure (OSHA)
• OSHA standard interpretation, February 3, 1984 - baseline audiograms and mobile testing
• CAOHC - Occupational Hearing Conservationist FAQ