Written and maintained by CASRAI Editorial Board
Last updated
General equipment information from US federal regulations, not medical advice and not a testing procedure. Regulation text checked 2026-10-30.
Short answer
US rules do not sort audiometers into a long list of product categories. FDA defines one device, the audiometer (Class II), and sets it apart from the tympanometer and the otoacoustic emission (OAE) device. OSHA’s occupational noise standard names the audiometer kinds it addresses: microprocessor, pulsed-tone and self-recording. The sections below put those regulatory lines side by side.
Definition and scope
Under 21 CFR 874.1050, FDA describes an audiometer or automated audiometer as an electroacoustic device that produces controlled levels of test tones and signals, intended for diagnostic hearing evaluations and for assisting in the diagnosis of possible otologic disorders. It is Class II. It is generally exempt from premarket notification if it complies with ANSI S3.6-1996, “Specification for Audiometers,” subject to the limitations in 21 CFR 874.9. The exemption does not cover the otoacoustic emission device.
How audiometers are described in practice
The OSHA occupational noise standard, 29 CFR 1910.95, is where the regulations say most about how an audiometer is used on the job. Paragraph (h) requires audiometric tests to be pure tone, air conduction, hearing threshold examinations, covering at minimum 500, 1000, 2000, 3000, 4000 and 6000 Hz. It requires audiometers, including microprocessor audiometers, to meet ANSI S3.6-1969 and to be maintained and used accordingly. OSHA cites the 1969 edition, while FDA’s exemption cites the 1996 edition; the two rules name different editions and each applies in its own context. Separately, paragraph (g)(3) says who may perform the tests: a licensed or certified audiologist, otolaryngologist or other physician, or a technician who is certified or has demonstrated competence. That is a staffing rule, not guidance on how to run a test.
Types the regulations name
| Type | What the regulation says | Source |
|---|---|---|
| Microprocessor audiometer | Included in the audiometers that must meet ANSI S3.6-1969 and be maintained and used in accordance with it. | 29 CFR 1910.95(h) |
| Pulsed-tone audiometer | Paragraph (h)(3) sends pulsed-tone audiometers to Appendix C, which requires a tone on-time of at least 200 milliseconds. | 29 CFR 1910.95(h)(3) and Appendix C |
| Self-recording audiometer | Appendix C covers its calibration: 30-second (plus or minus 3 s) dwell per test frequency, chart lines every 10 dB at least 1/4 inch apart, pen trace no wider than 2 dB, attenuator slew of at most 6 dB per second. | 29 CFR 1910.95 Appendix C |
| Audiometer / automated audiometer (FDA device) | Electroacoustic device producing controlled levels of test tones; Class II; ANSI S3.6-1996 compliance supports the premarket-notification exemption. | 21 CFR 874.1050 |
Audiometer parts, as the regulations describe them
The regulations do not give a parts list. They describe the tone-producing function (controlled levels of test tones), and Appendix C refers to an attenuator, a recording stylus (pen) and a chart for the self-recording kind. Anything beyond that, such as transducer or response-switch designs, comes from manufacturer documentation for a specific model.
Audiometer vs tympanometer vs OAE device
| Device | FDA description | Regulation |
|---|---|---|
| Audiometer | Produces controlled levels of test tones for diagnostic hearing evaluations. | 21 CFR 874.1050 (Class II; exempt if ANSI S3.6-1996 is met) |
| Tympanometer / auditory impedance tester | Changes air pressure in the external auditory canal and measures and graphs eardrum mobility to evaluate middle-ear function. | 21 CFR 874.1090 (Class II, special controls; exempt when it complies with FDA-recognized consensus standard ANSI S3.39) |
| Otoacoustic emission device | Excluded from the audiometer premarket-notification exemption. | 21 CFR 874.1050(b) |
So the tympanometer vs audiometer question comes down to what each is for: one presents tones, the other changes ear-canal pressure and measures eardrum mobility. For the OAE device, the audiometer rule’s only statement is the exemption exclusion; for probe tips and other consumables, use the manufacturer’s instructions for use for that device.
Where it matters for labs, clinics and supply decisions
Where a program falls under 29 CFR 1910.95, the standard sets a calibration and room checklist that applies to the audiometer in use:
| Check | Interval and trigger in the standard |
|---|---|
| Functional check | Before each day’s use, with a person of known, stable hearing thresholds; a deviation of 10 dB or more requires an acoustic calibration. |
| Acoustic calibration check | At least annually (frequencies below 500 Hz and above 6000 Hz may be omitted); a deviation of 15 dB or more requires an exhaustive calibration. |
| Exhaustive calibration | At least every two years, to the sections of ANSI S3.6-1969 listed in the standard. |
| Test-room background level (Appendix D, octave-band maximums) | 40 dB at 500 Hz, 40 dB at 1000 Hz, 47 dB at 2000 Hz, 57 dB at 4000 Hz, 62 dB at 8000 Hz. |
For a related instrument, see the tuning fork guide. Clinic planning pages that mention audiometers as capital equipment include the audiology clinic supply checklist and the occupational medicine clinic supply checklist.
Common misunderstandings
- “There is one audiometer standard year.” FDA’s exemption refers to ANSI S3.6-1996; OSHA’s rule refers to ANSI S3.6-1969. Check which rule applies to your program.
- “A tympanometer is a kind of audiometer.” In the regulations they are separate devices with separate sections (874.1090 and 874.1050).
- “Appendix C applies to every audiometer.” It covers self-recording and pulsed-tone audiometers only.
FAQ
What are the parts of an audiometer?
The regulations describe a device that produces controlled levels of test tones; Appendix C of 29 CFR 1910.95 adds an attenuator, stylus and chart for the self-recording kind. Detailed parts lists come from a manufacturer’s documentation.
What is the difference between a tympanometer and an audiometer?
An audiometer produces controlled test tones (21 CFR 874.1050). A tympanometer changes air pressure in the ear canal and measures eardrum mobility (21 CFR 874.1090).
Are OAE probe tips part of the audiometer rules?
No. The audiometer rule only excludes the otoacoustic emission device from the premarket-notification exemption. Probe tips are covered by the specific device’s manufacturer instructions.
How often must an OSHA-covered audiometer be calibrated?
A functional check before each day’s use, an acoustic check at least annually, and an exhaustive calibration at least every two years (29 CFR 1910.95(h)(5)).
Sources
- 21 CFR 874.1050, Audiometer: law.cornell.edu/cfr/text/21/874.1050 (checked 2026-10-30)
- 21 CFR 874.1090, Auditory impedance tester: law.cornell.edu/cfr/text/21/874.1090 (checked 2026-10-30)
- 29 CFR 1910.95, Occupational noise exposure: law.cornell.edu/cfr/text/29/1910.95 (checked 2026-10-30)
- OSHA, 1910.95 Appendix C (audiometer calibration and self-recording audiometers): osha.gov, Appendix C (checked 2026-10-30)
- OSHA, 1910.95 Appendix D (audiometric test rooms): osha.gov, Appendix D (checked 2026-10-30)
