46 CFR 10.306: Hearing standards for mariner credential applicants
Last reviewed: October 14, 2026
This section sets hearing tests for mariner credential applicants when the examining medical practitioner has concerns about hearing. It sets an audiometer threshold and speech discrimination percentages. It also covers waivers and an operational limitation for mariners who need hearing aids.
Applies toApplicants for a merchant mariner credential or endorsement, including renewal or raise of grade, whose hearing the examining medical practitioner has concerns about.
What it says
If the practitioner doing the general medical exam is concerned that an applicant's hearing may affect maritime safety, the practitioner must refer the applicant to an audiologist or other hearing specialist for an audiometer test and a speech discrimination test, as appropriate.
46 CFR 10.306(a)“the examining medical practitioner must refer the applicant to an audiologist or other hearing specialist to conduct an audiometer test and a speech discrimination test, as appropriate”
The audiometer test must include testing at 500 Hz, 1,000 Hz, 2,000 Hz, and 3,000 Hz.
46 CFR 10.306(b)“The audiometer test must include testing at the following thresholds: 500 Hz; 1,000 Hz; 2,000 Hz; and 3,000 Hz.”
The frequency responses for each ear must be averaged to measure the applicant's hearing ability.
46 CFR 10.306(b)“The frequency responses for each ear must be averaged to determine the measure of an applicant's hearing ability.”
Applicants must demonstrate an unaided threshold of 30 decibels or less in at least one ear.
46 CFR 10.306(b)“Applicants must demonstrate an unaided threshold of 30 decibels or less in at least one ear.”
The functional speech discrimination test must be carried out at a level of 65 decibels.
46 CFR 10.306(c)“The functional speech discrimination test must be carried out at a level of 65 decibels.”
For an original MMC or endorsement, the applicant must demonstrate functional speech discrimination of at least 90 percent.
46 CFR 10.306(c)“For issuance of an original MMC or endorsement the applicant must demonstrate functional speech discrimination of at least 90 percent.”
For renewal or raise of grade, the applicant must demonstrate functional speech discrimination of at least 80 percent.
46 CFR 10.306(c)“For renewal or raise of grade, the applicant must demonstrate functional speech discrimination of at least 80 percent.”
If a mariner needs hearing aids to meet the hearing standards, the mariner may not serve under the endorsement unless the hearing aids are worn in the operational mode and spare batteries are carried onboard a vessel.
46 CFR 10.306(e)“a mariner may not serve under the authority of the endorsement unless hearing aids are worn in the operational mode, and spare batteries are carried onboard a vessel”
Common questions
Can I get a waiver if I fail the hearing audiometer test?
You may be eligible for a medical waiver under § 10.303 of this subpart if you cannot meet the audiometer standards but can pass the functional speech discrimination test, or if you need hearing aids to meet the standards.
“An applicant who is unable to meet the hearing standards of the audiometer test, but who can pass the functional speech discrimination test; or who requires hearing aids to meet the hearing standards, may be eligible for a medical waiver in accordance with § 10.303 of this subpart.”
What speech discrimination score do I need for renewal?
For renewal or raise of grade, you must demonstrate functional speech discrimination of at least 80 percent.
“For renewal or raise of grade, the applicant must demonstrate functional speech discrimination of at least 80 percent.”
Can I work as a mariner if I need hearing aids?
You may not serve under the endorsement unless you wear the hearing aids in the operational mode and carry spare batteries onboard a vessel. This limitation will be placed on your medical certificate.
“This operational limitation will be placed on their medical certificate.”
What hearing level must I show on the audiometer test?
You must demonstrate an unaided threshold of 30 decibels or less in at least one ear.
“Applicants must demonstrate an unaided threshold of 30 decibels or less in at least one ear.”
The text of 46 CFR 10.306
Electronic Code of Federal Regulations (eCFR), current as of April 16, 2026 · Read it on eCFR
Hearing requirements
(a) If the medical practitioner conducting the general medical exam has concerns that an applicant's ability to hear may impact maritime safety, the examining medical practitioner must refer the applicant to an audiologist or other hearing specialist to conduct an audiometer test and a speech discrimination test, as appropriate.
(b) The audiometer test must include testing at the following thresholds: 500 Hz; 1,000 Hz; 2,000 Hz; and 3,000 Hz. The frequency responses for each ear must be averaged to determine the measure of an applicant's hearing ability. Applicants must demonstrate an unaided threshold of 30 decibels or less in at least one ear.
(c) The functional speech discrimination test must be carried out at a level of 65 decibels. For issuance of an original MMC or endorsement the applicant must demonstrate functional speech discrimination of at least 90 percent. For renewal or raise of grade, the applicant must demonstrate functional speech discrimination of at least 80 percent.
(d) Hearing waivers. An applicant who is unable to meet the hearing standards of the audiometer test, but who can pass the functional speech discrimination test; or who requires hearing aids to meet the hearing standards, may be eligible for a medical waiver in accordance with § 10.303 of this subpart.
(e) Hearing operational limitation. If hearing aids are required in order to meet the hearing standards above, a mariner may not serve under the authority of the endorsement unless hearing aids are worn in the operational mode, and spare batteries are carried onboard a vessel. This operational limitation will be placed on their medical certificate.
Sections it refers to
The plain-English explanation on this page was written with AI from the regulation text above and checked automatically before publishing: every quote appears in the text, every number comes from it, and a second model confirmed each statement adds nothing the text doesn't say. Regulation text current as of April 16, 2026. The regulation text governs. RegKnot is not affiliated with the U.S. Coast Guard.