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The human auditory system
is composed of three parts;
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the outer ear, the middle ear,
and the inner ear.
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Let's see how it works.
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The sound waves are picked up
by the ear pavilion of the outer ear.
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They are then amplified and transmitted
to the middle ear through
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the external ear canal.
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This movement of the sound
makes this small membrane,
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called the eardrum (to) vibrate.
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These vibrations are transmitted to
the ossicle, located in the middle ear.
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The ossicles are the smallest bone
in the human body.
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They're composed of the malleus,
which transmits the vibrations
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to the incus, then to the stapes,
which acts as a piston
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that compresses the
fluid of the inner ear.
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The cochlea is the main organ
of auditory perception.
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It contains between 15,000 to 20,000
hair cells that detect vibrations of
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the liquid, and generates nerve
impulses that are sent to the brain
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via the auditory nerve.
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But this system is fragile
and can suffer failures.
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We call this hearing loss, two of which
are conduction hearing loss
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and sensorineural hearing loss.
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Conduction hearing loss can be caused
by an obstruction in the ear canal,
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such as ear wax, a perforated eardrum,
a malfunction of the ossicles,
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otitis, or fluid in the middle ear.
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This type of loss can often be resolved
by medical intervention, and represents
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only 10% of cases of hearing loss.
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The second type of loss, sensorineural
hearing loss, represents 90% of cases.
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It results from the destruction of
hair cells in the cochlea.
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It is often due to ageing
[coughing], can be genetic,
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or the consequence of repeated exposure
to very loud sounds. [loud drilling]
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Ughh! Okay, this type of loss is
irreversible (what?!)
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Yes, it's a shame. But can often be
compensated by hearing aid.
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[cheering and clapping]
