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Hearing is one of the five human
senses.
Hearing | Sight | Smell | Taste | Touch
How We Hear
We use our ears to hear sounds.
Sounds travel through the air and our ears as sound waves.
How We Hear
• Sound waves are collected
by the outer part of the ear,
called the pinna.
• The pinna is the only part of
the ear that you can see
with your eye.
How We Hear
• After the sound waves are
collected by the pinna they
are sent through the ear
canal before reaching the
ear drum.
• When the sound waves hit
the ear drum, it vibrates.
How We Hear
• The vibrations from the ear
drum make three small
bones in the ear vibrate.
o The hammer
o The anvil
o The stirrup
stirrup
• Those three bones together
are called the ossicles.
anvil
hammer
How We Hear
• The vibration of the
ossicles transfer the sound
waves to the inner ear.
• The inner ear has two
parts, the cochlea and the
semicircular canals.
• The semicircular canals.
help you determine
movement and to stay
balanced.
semicircular canals
cochlea
How We Hear
• As the sound waves pass
through the cochlea, they
cause microscopic hair cells
to vibrate.
• These hair cells, called cilia,
are linked to the auditory
nerve. When the cilia
vibrate they send an electric
impulse signal to the brain.
• When the signal reaches
the brain, we hear!
auditory nerve
cochlea
Cilia
From David J. Lim. Functional Structure of the Organ of
Corti: A Review. Hearing Research, 22 (1986) 117-146
How We Hear
• As the sound waves pass
through the cochlea, they
cause microscopic hair cells
to vibrate.
• These hair cells, called cilia,
are linked to the auditory
nerve. When the cilia
vibrate they send an electric
impulse signal to our brain.
• When the signal reaches
the brain, we hear!
auditory nerve
cochlea
Cilia
From David J. Lim. Functional Structure of the Organ of
Corti: A Review. Hearing Research, 22 (1986) 117-146
Now imagine not being
able to hear your friends
and parents talk.
That’s Hearing
Loss!
NIHL (Noise-Induced Hearing Loss)
Hearing loss as a result of prolonged or sudden exposure to loud noise.
• When we are exposed to
noises that are too loud,
our tiny hair cells in the
cochlea vibrate too hard.
• The vibrations cause them
to break and bend.
From David J. Lim. Functional Structure of the Organ of Corti: A
Review. Hearing Research, 22 (1986) 117-146 Elsevier
NIHL
• Once our microscopic hair
cells bend and break, they
will never be straight again.
• There is no surgery to fix
the hair cells, once they are
damaged they will never
work properly again.
• To treat NIHL visit an
audiologist.
From David J. Lim. Functional Structure of the Organ of Corti: A
Review. Hearing Research, 22 (1986) 117-146 Elsevier
Audiologist
An audiologist is the person you visit to
have your ears checked.
• He or she will look inside your ears to make sure everything
looks alright
• He or she will do a hearing test to make sure you are hearing
everything alright.
If the audiologist finds that you have hearing loss, he or she will
work with you to select and fit hearing aids so you can hear again.
Noise levels or loudness are measured in decibels (dB).
Any loud noise over 85dB is considered loud enough to
cause NIHL.
• 30 dB Whisper
• 60 dB Normal
conversation or a
dishwasher
• 70 dB A vacuum
Cleaner
• 80 dB Alarm Clock
• 90 dB A hair dryer, or
lawn mower
• 100 dB MP3 players at
full volume
• 110 dB Concerts and
sporting events
• 130 dB Ambulance
Levels of
Noise chart.
3 Ways to Protect
Your Hearing
Walk Away
• If the noise around you is too loud, walk away.
• Moving back 10 or 15 feet from the noise can make the noise
going into your ears less loud.
• If you are in a noisy place, make sure you only stay for 30
minutes, if you are not wearing any ear protection.
Turn It Down
• When TVs, car stereos, and MP3 players are turned up too
loud, the noise can hurt your ears.
• Turn down the volume to protect your ears.
o Keep the volume at 50%.
o When listening to anything with ear buds or ear phones, if
someone next to you can hear what you are hearing,
the volume is probably too loud.
Wear Ear Protection
• If you know you are going to be in a loud area with noise over
85 dB, wear ear protection.
o Earplugs
o Custom (made to fit your ear) earplugs
See an audiologist for these, similar to what musicians and
pilots wear.
If you think you or someone
you know might have
a hearing problem,
tell your parents to go online to
www.HowsYourHearing.org
to find an audiologist near you.
Questions???