How Audiologists Test Hearing
What happens in a hearing test? Hearing exam procedures in a complete audiological evaluation.
Pure Tone Testing
Image courtesy of US NIOSH
A thorough hearing evaluation has a number of important components, but the central feature is the classic pure tone testing. For this test, you go into a soundproofed booth that has a window, and put on a pair of headphones (or sometimes earphones). The
audiologist or technician
outside the booth uses an audiometer to generate calibrated tones at a range of frequencies (pitches) and loudness levels, which are played through your headphones. You make a signal each time you hear a tone, by pressing a button or raising your hand.
Each ear is tested separately, at frequencies ranging from 125 to 8000 hertz (Hz). By trying different volumes, the person doing the testing can identify the quietest sound you are able to detect at each frequency, for each ear. This is your hearing threshold at that frequency, and it is measured in decibels (dB). The lower the threshold, the better your hearing; 0 dB is ideal.
This segment of the pure tone test, the part that uses headphones or earphones, is called the air conduction test. The other portion of the pure tone test is very similar, but instead of using headphones to transmit the tones, a small vibrating element is placed against the skull, usually behind the ear. This bone conduction test bypasses the outer and middle ear, and conducts the sound through the bone directly to the inner ear.
Using the results from the air conduction and the bone conduction portions of the pure tone test, the evaluator can determine:
- The type of hearing loss:
- Sensorineural (as in most cases of
noise-induced hearing loss)
- Conductive (for example, caused by infection or a blockage in the ear canal)
- Mixed (having both sensorineural and conductive components)
overall degree of hearing loss
- The configuration (shape) of the hearing loss: the relative severity of the loss at different frequencies
Other Steps in Testing Hearing
The pure tone testing is only one part of a thorough audiological assessment. A complete evaluation by an
will also include the following:
- Questions about your hearing history and medications
- Physical inspection of the ears (otoscopy), and possibly removal of excess ear wax
- Tympanometry and measurement of acoustic reflexes. These test the flexibility and responsiveness of the eardrum, and the functioning of the ear's protective mechanisms in response to loud sounds.
- Speech tests:
- Speech recognition threshold
- Most comfortable listening level
- Uncomfortable loudness level
- Word recognition (speech discrimination) test
- Recruitment (abnormal loudness) testing by frequency
All of these help build a
picture of your individual hearing profile,
and contribute in identifying the best approaches for treatment.
Where to Go to Get a Hearing Test
How to Interpret Your Hearing Test Results
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