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Audiometry
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Pure-tone audiometry is the test that can tell how much hearing has been lost, at which frequencies, and what type of loss it is. A pure tone is a sound of a single frequency, with nothing mixed in.
The test uses two different routes to reach the ear. One is air conduction: the sound comes in through the ear canal, moves the eardrum and the ossicular chain, and from there passes to the cochlea, the snail-shaped structure where sound becomes a nerve signal. The other is bone conduction, in which a vibrator resting on the mastoid, the bone behind the ear, makes the cochlea vibrate directly. One pathway knocks at the door and the other pounds on the wall, skipping the entrance.
Comparing the two is what separates conductive hearing loss, where the problem lies in the path from the auricle to the ossicles, from sensorineural hearing loss, where the problem is the cochlea or what comes after it. And the threshold, the number that gets written down, is the softest sound the person can hear at least half the time.
In brief
Pure-tone audiometry can determine the degree, configuration, and type of a hearing loss.
It tests two pathways: air conduction, which travels through the ear canal, eardrum, and ossicular chain, and bone conduction, which vibrates the cochlea from the mastoid.
One pathway knocks at the door and the other pounds on the wall, skipping the entrance.
Comparing the two separates conductive from sensorineural hearing loss; the threshold is the softest sound heard at least half the time.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingAudiology Pure Tone Evaluation, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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