Bellwork: The Ear
• What is the function of the ear?
• Are there different parts? If so, can you
name them?
• How does the ear work?
• What is that sound?
A Story About the Ear
Mrs. Mackens
Anatomy of the Ear
o Outer Ear
• Pinna
• Ear Canal
• Outer layer of the eardrum
o Middle Ear
• Hammer
• Anvil
• Stirrup
o Inner Ear
• Cochlea
• Nerves
• Semicircular Canals
How Sound Travels
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First, sound is collected by the pinna (the visible part of
the outer ear)
Then, it is directed into the outer ear canal
Next, sound makes the eardrum vibrate
Now, the vibration causes three tiny bones in the inner
ear to vibrate
 Hammer
 Anvil
 Stirrup
Vibration of the eardrum
How Sound Travels
Finally, the vibration is transferred to the
snail-shaped cochlea in the inner ear
The cochlea is lined with sensitive hair
cells (cilia)
The hair cells (cilia) trigger the generation
of nerve signals that are sent to the brain
Outer Ear
Pinna- the visible part of the outer ear. It
collects sound and directs it into the outer
ear canal.
Ear Canal- the tube through which sound
travels to the eardrum
Outer layer of eardrum- (tympanic
membrane) vibrates when sound waves
reach it
Middle Ear
 Hammer (Malleus)- a tiny bone that passes
vibrations
 Anvil (Incus)- a tiny bone that passes vibrations
from the hammer to the stirrup
 Stirrup (Stapes)- a tiny, U-shaped bone that passes
vibrations from the stirrup to the cochlea. This is
the smallest bone in the human body. (.25 to .33 cm
long)
 Eustachian tube- a tube that connects the middle
ear to the back of the nose; it equalizes the pressure
between the middle ear and the air outside.
• Babies can get earaches because of milk backing
up in the Eustachian tube, which causes bacteria
to grow and may cause hearing problems later in
life.
• An earache is caused by too much fluid putting
pressure on your eardrum. Earaches are often the
result of an infection, allergies or a virus.
Inner Ear
 Cochlea- a spiral-shaped, fluid-filled inner ear structure;
it is lined with cilia (tiny hairs) that move when vibrated
and cause a nerve impulse to form.
 Nerves- these carry electro-chemical signals from the
inner ear (the cochlea) to the brain.
 Semicircular Canals- Fluid filled tubes attached to the
cochlea that help us maintain our sense of balance.
Semicircular Canals
Stirrup
Nerves
Anvil
Hammer
Pinna
Cochlea
Eardrum
Eustachian Tube
Outer Ear Canal
Day or Night,
Ears Keep You Upright
• When you move your head, the liquid in
the semicircular canals moves, too.
• The liquid moves the tiny hairs, which
send a nerve message to your brain about
the position of your head.
• In less than a second, your brain sends
messages to the right muscles so that you
keep your balance.
Dizzy yet?
• Sometimes the liquid in your semicircular
canals keeps moving after you've stopped
moving.
– spin in circles or go on the Tilt-A-Whirl at the
amusement park.
• Your brain is getting two different
messages and is confused about the
position of your head.
Balance Disorders
• A condition that makes you feel unsteady
or dizzy, as if you are moving, spinning, or
floating, even though you are standing still
or lying down.
• Can be caused by viral or bacterial
infections in the ear, a head injury, or
blood circulation problem. Many people
experience problems with their sense of
balance as they get older.
Hearing Loss
• There are three kinds of
hearing loss:
–Sensorineural
–Conductive
–Mixed hearing loss
Sensorineural Hearing Loss
• Also known as nerve deafness
• the inner ear or actual hearing nerve itself
is damaged
• About 90% of all people with hearing
impairments suffer from sensorineural
hearing loss
• Most common
Sensorineural Hearing Loss
• Usually permanent
• not medically or surgically treatable
• In most cases, the cillia or the nerves from
the inner ear to the brain are irreparably
damaged.
• wearing hearing aids may be of significant
benefit
Conductive Hearing Loss
• outer and/or middle part of the ear
fail to work properly
• Sounds become "blocked" and are not
carried all the way to the inner ear
(where hearing is still normal)
• Not permanent; temporary hearing
loss
Mixed Hearing Loss
• A combination of a conductive and
sensorineural hearing loss
• Both the middle and inner ear are involved
Causes of Sensorineural
Hearing Loss
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•
•
•
•
the natural aging process
exposure to loud noises
infection or other disease
a genetic disorder
Tinnitus, or ringing in the ears, is usually
associated with sensorineural hearing loss
Causes of Conductive Hearing Loss
•
•
•
•
a buildup of fluid in the middle ear
wax in the ear canal
puncturing of the eardrum
problems or injury to the bones or
membrane — which carry sound from the
external ear through the middle ear to the
inner ear.
Causes of a Mixed Hearing Loss
• This hearing disorder can also occur when a
person first just has a permanent sensorineural
hearing loss and then also develops a conductive
hearing loss.
• For example, a person who already has a
sensorineural loss gets a middle ear infection, and
the two types of loss combine to create a greater
hearing loss.
• Some other instances of mixed hearing loss are
the result of the outer and inner ear being
malformed, which causes both types of hearing
loss
Treatment
• Conductive hearing loss can be easier to
remedy than sensorineural or mixed
hearing loss.
• It is usually treatable with either medical
or surgical intervention
• In cases where medical/surgical
intervention is not an option, a hearing aid
can be very helpful.
Treatment
• Sensorineural hearing loss is usually
permanent
• no medically or surgically treatable. In
most cases, the nerves from the inner ear to
the brain are irreparably damaged.
• However, most people with this hearing
loss find wearing hearing aids to be of
significant benefit
Treatment for Mixed Hearing Loss
• With mixed hearing loss, the conductive
part may be treated, but the
sensorineural part is usually permanent.
Hearing Instruments
• Small, comfortable, and almost invisible
• Consists of a microphone, an amplifier or
processor and a speaker, which transmits
the enhanced sound waves into your ear.
• A tiny battery supplies the necessary power
Hearing Instruments
• The ear remains open and receptive to
those sounds which can still be heard
naturally.
• They amplify speech, tones and sounds
exactly when they need to.
• In complex hearing situations they pick out
the signals you really want to hear.
Hearing Instruments
• That they focus the hearing on the desired
source, and block out unwanted
background noise. You can now hear the
person you are speaking with, despite loud
music and background conversation.
• In cases of moderate hearing loss, modern
hearing aids can restore up to 100% of
hearing capability.
Types of Hearing Instruments
• In-the-ear models
(ITE or ITC/CIC
models)
• Behind-the-ear
models (CRT and
BTE models)
Levels of Hearing Loss
• Bilateral- both ears are impaired
• Unilateral- one ear is impaired
Bilateral Hearing Loss
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•
•
•
Mild
Moderate
Severe
Profound
Mild Hearing Loss
• A mild hearing loss may cause you to miss 2540% of the speech signal.
• Usually this results in problems with clarity since
the brain is receiving some sounds but not all of
the information.
• Symptoms of mild hearing loss include problems
understanding someone farther away than a
normal distance for conversation, or even up
close if the background environment is noisy.
• Weak voices are also difficult to understand for
people with mild hearing losses.
Moderate Hearing Loss
• A moderate hearing loss may cause you to miss
50-75% of the speech signal.
• This means you would not have problems
hearing at short distances and understanding
people face-to-face, but you would have
problems if distance or visual cues changed.
• Symptoms of moderate hearing loss include
problems hearing normal conversations and
problems hearing consonants in words
Severe Hearing Loss
• People with severe hearing loss have difficulty
hearing in all situations.
• Speech may be heard only if the speaker is
talking loudly or at close range.
• A severe hearing loss may sometimes cause you
to miss up to 100% of the speech signal.
• Symptoms of severe hearing loss include
inability to have conversations except under the
most ideal circumstances (i.e., face-to-face, in
quiet, and accompanied with speechreading).
Profound Hearing Loss
• Profound hearing loss is the most extreme
hearing loss.
• A profound hearing loss means that you
may not hear loud speech or any speech at
all.
– You are forced to rely on visual cues instead
of hearing as your main method of
communication. This may include signlanguage and/or speechreading (also
commonly referred to as "lipreading")
• Children have more sensitive ears than adults.
They can recognize a wider variety of noises.
• Dolphins have the best sense of hearing among
animals. They are able to hear 14 times better
than humans.
• Animals hear more sounds than humans.
• Decibels (dB)- the intensity (volume or
loudness) of a sound
– A whisper is about 20 dB
– loud music (some concerts) is around 80 to
120 dB
– and a jet engine is about 140 to 180 dB
– Usually, sounds greater than 85 dB can cause
hearing loss in a few hours; louder sounds
can cause immediate pain, and hearing loss
can develop in a very short time
How Hearing Loss is Measured
• Hertz- a range of frequencies
• The tone of sound is measured in cycles per second
(cps) or Hertz.
• Low bass tones range around 50 to 60 Hz
• Shrill, high - pitched tones range around 10,000 Hz
or higher
• The normal range of human hearing is about 20 Hz
to 20,000 Hz
• Some people can hear within a slightly higher range
• Animals can hear up to about 50,000 Hz.
Identifying Hearing Loss
• Ranges have been established to help people identify
how much difficulty they should expect from their
hearing loss. The typical ranges for an adult are:
• -10dB to 25dB = Normal range
• 26dB to 40 dB = Mild hearing loss
• 41 dB to 55 dB = Moderate hearing loss
• 56 dB to 70 dB = Moderately Severe hearing loss
• 71 dB to 90 dB = Severe hearing loss
• over 90 dB = Profound hearing loss
Audiogram
• Hearing loss is plotted on an audiogram
• Right ear is represented by a red circle
• Left ear is represented by a blue X
Audiogram
• 10dB to 25dB =
Normal hearing
• 26dB to 40 dB =
Mild hearing loss
• 41 dB to 55 dB =
Moderate hearing loss
• 56 dB to 70 dB =
Moderately-Severe loss
• 71 dB to 90 dB =
Severe hearing loss
• over 90 dB =
Profound hearing loss
Decibels
Hertz
Hertz/Decibels
Identify the Hearing Loss
What type of
hearing loss
is it?
Normal Hearing
Mild Hearing Loss
Moderate Loss
Profound Hearing Loss
Unilateral Hearing Loss
Speech Banana
Ear Conditions
• Earache: Pain in the ear can have many causes. Some
of these are serious, some are not serious.
• Otitis media (middle ear inflammation): Inflammation
or infection of the middle ear (behind the eardrum).
Usually, this is caused by an infection.
• Swimmer’s ear (Otitis externa): Inflammation or
infection of the outer ear (pinna and ear canal). Sudden
cases are usually infections; chronic otitis is often a
skin condition (dermatitis).
Ear Conditions
• Meniere’s disease: A condition in which the inner ear
on one side malfunctions. Vertigo, tinnitus, hearing
loss, and pain are common symptoms.
• Tinnitus: Ringing in one or both ears. Usually this is
due to damage from noise exposure, or from aging.
• Cerumen (ear wax) impaction: Ear wax may block
the ear canal and adhere to the eardrum. The
eardrum’s reduced vibrations impair hearing.
Ear Conditions
• Ruptured eardrum: Very loud noises, sudden changes
in air pressure, or foreign objects can tear the
eardrum. The small hole usually heals within a few
weeks.
• Acoustic neuroma: A noncancerous tumor that grows
on the nerve traveling from the ear to the brain.
Hearing loss, vertigo, and tinnitus can be symptoms.
• Mastoiditis: Infection of the mastoid bone, just
behind the ear. Mastoiditis was once a common
complication of untreated ear infections.
Ear Conditions
• Benign paroxysmal positional vertigo (BPPV): A
disruption of function in the inner ear, causing
episodes of vertigo. Although not medically serious,
its symptoms can be distressing.
• Cholesteatoma: This is a benign condition. It is the
buildup of fibrous tissue within the middle ear and
surrounding bones. Often there is a foul smelling
discharge associated with hearing loss.