The instructions for conducting the hearing portion of the examination are as follows from the regulations:
Note evidence of any ear disease, symptoms of aural vertigo, or Meniere’s Syndrome. When recording hearing, record distance from patient at which a forced whispered voice can first be heard. For the whispered voice test, the individual should be stationed at least 5 feet from the examiner with the ear being tested turned toward the examiner. The other ear is covered. Using the breath which remains after a normal expiration, the examiner whispers words or random numbers such as 66, 18, 23, etc. The examiner should not use only sibilants (s-sounding test materials). The opposite ear should be tested in the same manner.
If the individual fails the whispered voice test, the audiometric test should be administered. For the audiometric test, record decibel loss at 500 Hz, 1,000 Hz, and 2,000 Hz. Average the decibel loss at 500 Hz, 1,000 Hz and 2,000 Hz and record as described on the form. If the individual fails the audiometric test and the whispered voice test has not been administered, the whispered voice test should be performed to determine if the standard applicable to that test can be met.
Note that if the audiometric exam is performed first and the driver fails, you should still perform the whisper test. If the driver passes either test, s/he passes the hearing portion of the exam. The audio exam does not “trump” the whisper test. If the driver wears hearing aids in both ears, you will need to refer him/her to an audiologist to conduct testing with the hearing aids. Make sure you mark the checkbox on the DOT exam form if hearing aids are needed.
If the driver only needs a hearing aid in one ear, go ahead and perform a whisper test on the good ear. If s/he passes, you’re good to go – you only need ONE good ear!
How to interpret audiogram results
When performing audiometry, only consider and record decibel loss at 500 Hz, 1000 Hz and 2000 Hz. The average loss must be no more than 40 dB in the better ear. If you are using a machine calibrated to ISO standards, you would convert the individual readings as indicated in below under “instructions”, then add together and divide by 3 to get the average.
The forced whisper test was administered first, and hearing measured by the test failed to meet the minimum five feet requirement in both ears. Therefore, the medical examiner also administered an audiometric test, resulting in (500, 1000 & 2000 Hz respectively):
Right ear 30 + 33 + 35 = 98/3 = 32.6 = PASS
Left ear 40 + 43 + 50 = 133/3 = 44.3 = FAIL
In this example, the driver passes the hearing portion of the exam as s/he has one good ear.
You don’t need an expensive audio booth to perform this test.
A fairly simple way to add audiometry to your practice is using this handheld device from Welch Allyn: