Download The Ear - Fort Bend ISD

How It Works and
Things That Can Go Wrong
 The
ear serves two functions: hearing and
balance.
 The organs for these functions are the
cochlea for hearing and the semicircular
canals for balance.
 The
pinna funnels sound into the ear canal.
 Sound waves go through the ear canal and
vibrate the eardrum (typanic membrane).
 The vibrations are transmitted through and
amplified by the ossicles (middle ear bones).
 Movement of the ossicles pushes at and pulls
away from the fluid in the inner ear.
 The
movement of the fluid in the inner ear
moves the hairs in the sensory cells of the
cochlea.
 These cells send impulses from the cochlea
through the auditory nerve to the auditory
cortex of the brain.
*The ear is changing sound energy to
vibrations, to nerve impulses. Anything that
stops the flow of energy can cause hearing
loss.
 Auditory
Cortex – the area of the brain that
receives and translates information about
sound.
 Auditory Nerve – a nerve that stretches from
the cochlea to the brain. It carries messages
from the ear to the brain.
 Cochlea – a part of the inner ear. It is shaped
like a snail. There are many tiny nerve
endings inside the cochlea.
 Decibel
– a unit for measuring how loud or
soft a sound is.
 Ear Canal – the passage that carries sound
from the pinna to the eardrum.
 Eardrum (Tympanic Membrane) – a small
opening inside the ear that is covered with
skin. The eardrum moves back and forth
when sound hits it. The eardrum lies
between the outer and middle ear.
 Eustachian
Tube – tube connecting middle ear
to the throat (drains fluid from the ear).
 Frequency – the number of sound waves per
second that a sound makes. This tells how
high or low a sound is.
 Hertz – a unit for measuring the frequency of
a sound
 Ossicles
– malleus, incus, and stapes, the
three tiny bones in the middle ear. These
are the smallest bones in the body.
 Outer ear – first section of the ear. It
includes the pinna and the ear canal.
 Middle ear – second section (we can’t see it).
It contains the ossicles.
 Inner ear – third section (can’t see). It
contains the semicircular canals, cochlea,
and auditory nerve.
 Pinna
– the part of the ear that we see
outside the head. It catches sound.
 Semicircular Canals – the structures (fluidfilled) that control the sense of balance.
 Sound Waves – how sound travels. Sound
moves in waves that we cannot see.
1.
Conductive Hearing Loss – anything that
goes wrong in the outer or middle ear.
These can include:
- wax buildup in the ear canal
- infections in the ear canal that cause
swelling
- infection, scarring, or holes in the
eardrum
- fluid buildup in middle ear
- limited movement of the ossicles
2.
Sensorineural Hearing Loss – any problems
which occur in the inner ear. These can
include:
- drug-induced damage of the cochlea
(chemotherapy, etc.)
- trauma to the cochlea (blow to the head,
noise damage, etc.)
- age-related hearing loss (presbycusis)
- a tumor on the auditory nerve
- some infections, such as meningitis
3.
Mixed Hearing Loss – both conductive and
sensorineural hearing loss.
4.
Central Hearing Loss – when there is a
problem in the auditory cortex of the brain.
This is the least common.
 Many
times, Conductive Hearing Loss can be
corrected by medication or surgery.
 Most of the time, Sensorineural or Central
Hearing Loss can’t be corrected.
 Mild
– difficulty hearing soft speech
 Moderate – difficulty understanding conversations, especially if there is background noise.
TV and radio volume must increase.
 Severe – normal speech is inaudible. May
only be able to hear loud or amplified
speech.
 Profound – completely deaf
More than 28 million Americans have some
degree of hearing loss. About 2 million of
them are considered profoundly deaf.
 Limit
your time in loud places.
 Wear earplugs in noisy situations.
 Don’t sit too close to speakers at concerts.
 Turn your headphones down! If the person
sitting next to you can hear the music, it’s
too loud.
 Decibel
Levels:
50-60 decibels
80-85
90-95
100-120
130 +
110-140
normal conversation
city traffic, garbage
disposal
lawn mower
chainsaw, tractor
headphones
rock concert, jet takeoff, shotgun,
jackhammer
 At
85 decibels, you should use hearing
protection for extended exposure.
 At 100 or more decibels, you should not go
more than 15 minutes without hearing
protection.
 At 140 decibels, repeated exposure of more
than one minute can cause hearing loss.