Hearing Test Device: How Audiometers Are Classified, Standardized and Calibrated

What the FDA calls a hearing test device

In FDA's device classification database, product code EWO carries the device name "Audiometer," regulation number 874.1050 and device class 2. The regulation, 21 CFR 874.1050, defines the device this way: "An audiometer or automated audiometer is an electroacoustic device that produces controlled levels of test tones and signals." Both the manual and the automated machine fall under the same rule.

The second paragraph of the rule sets the class and a condition. The audiometer is Class II, and "except for the otoacoustic emission device, the device is exempt from the premarket notification procedures in subpart E of part 807" "if it is in compliance with American National Standard Institute S3.6-1996," within limits the rule lists. Put simply, an audiometer that complies with that edition doesn't need a premarket notification, while the otoacoustic emission device, the one used for an OAE hearing test, isn't covered by that exemption.

Which edition of ANSI S3.6 each rule names

ANSI S3.6 is the American National Standard "Specification for Audiometers." Federal rules don't all cite the same edition, and the table above lines them up. OSHA's noise rule still names S3.6-1969 for workplace audiometers. The FDA regulation's exemption names S3.6-1996. FDA's list of recognized consensus standards, which makers use to declare conformity in premarket submissions, now carries ANSI ASA S3.6-2025 as recognition 4-350, with a date of entry of December 22, 2025.

The change of edition has a deadline. FDA writes that it "will accept declarations of conformity, in support of premarket submissions, to [Rec 4-275] until December 19, 2027," recognition 4-275 being the 2018 edition reaffirmed in 2023. After that date, a declaration to the 2018 edition "will not be accepted." The deadline concerns makers' submissions to FDA, not audiometers already in use.

FDA's summary of the 2018 edition also explains the types printed on spec sheets: "Audiometers used for diagnostic assessment are classified as Types 1, 2, or 3, while audiometers having air-conduction facilities only are classified as Type 4."

How often a workplace audiometer must be calibrated

Employers who run audiometric testing under OSHA's occupational noise rule, 29 CFR 1910.95, follow a written calibration schedule in paragraph (h)(5). It has three steps, shown in the second table.

Every day, "the functional operation of the audiometer shall be checked before each day's use by testing a person with known, stable hearing thresholds," and by listening for distorted or unwanted sounds. If that check is off by 10 decibels or more, the audiometer goes to an acoustic calibration. At least once a year, calibration is checked acoustically under the rule's appendix E, and a deviation of 15 decibels or more calls for an exhaustive calibration. Whatever those checks show, an exhaustive calibration is due at least every two years, against listed sections of S3.6-1969.

The same rule says what the machine has to test: pure tone, air conduction thresholds, at 500, 1000, 2000, 3000, 4000 and 6000 Hz at a minimum, each ear separately. Noise limits that trigger the program are on our safe decibel levels page.

Who runs a workplace hearing test, and in what room

The same OSHA rule sets conditions around the device. Workplace audiograms must be done by "a licensed or certified audiologist, otolaryngologist, or other physician, or by a technician who is certified by the Council of Accreditation in Occupational Hearing Conservation," or by a technician who has shown competence, including in checking calibration.

Two kinds of machine carry an extra requirement: "pulsed-tone and self-recording audiometers, if used, shall meet the requirements specified in appendix C." The room matters too, since examinations "shall be administered in a room meeting the requirements listed in appendix D." And each employee's audiogram record has to show the "date of the last acoustic or exhaustive calibration of the audiometer," so the device's calibration history travels with every test result.

The hearing tests an audiometer runs, by billing code

Billing codes split audiometry by what is tested. In the CMS 2026 physician fee schedule file, 92551 is labelled "Pure tone hearing test air," 92552 "Pure tone audiometry air," 92553 "Audiometry air & bone," 92555 "Speech threshold audiometry," 92556 "Speech audiometry complete" and 92557 "Comprehensive hearing test." These are CMS short labels, not the full CPT descriptions.

Each code pays for the test, not the machine. What Medicare allows for each one is on our hearing test cost page, and whether Medicare covers the visit is on does Medicare cover a hearing test.