Download Causes of Hearing Loss - Mahtomedi High School

The
Ear and Hearing
The Ear
How the Ear Works -
videos
Statistics:
Understanding Hearing Loss
 U.S. population 320+ million
2.5 million Deaf
34 million Hard of Hearing
 1 of every 10 people has a
hearing loss
 Over age 65, 1 in every 3 persons
has some degree of hearing loss
Developed by HLA-Wake County,
Raleigh, NC
How Sound Travels
 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 (the ossicles) in the inner ear to
vibrate
 Hammer
Anvil
Stirrup
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
The hair cells trigger the generation
of nerve signals that are sent to the
brain
Hearing Loss
*Unilateral loss: hearing loss in one ear.
*Bilateral loss: hearing loss in both ears.
*There are three kinds of hearing loss:
•Sensorineural
•Conductive
•Mixed hearing loss
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
Causes and Treatment 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
 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.
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 this type of loss
Most common
Usually permanent
not medically or surgically treatable
In most cases, the hair cells or the nerves from the
inner ear to the brain are irreparably damaged.
wearing hearing aids may be of significant benefit
Causes of Sensorineural
Hearing Loss
 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
Mixed Hearing Loss
A combination of Conductive
and Sensorineural
Noise!
A major contributor to hearing loss in teenagers and
adults.
It can be prevented.
Levels 85 and up are considered unsafe
Interactive Sound Ruler
• City or freeway traffic 70 dB
• Hair dryer/alarm clock 80 dB
• Mowing the lawn- 90 dB
• Riding a motorcycle – 90 dB
• Race car/dance club- 110 dB
• Firecracker 140 dB
Degree of Hearing Loss
 Normal
 Mild
 Moderate
 Severe
 Profound
Mild Hearing Loss
 A mild hearing loss may cause you to miss
25-40% 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 sign-language and/or
speechreading (also commonly referred to as
"lipreading")
Measuring your hearing
 Hearing threshold
How is hearing measured:
Decibels (dB)-
the intensity
(volume or loudness)
of a sound
 A whisper is about
20-30 dB
 loud music is
around 80 to 120
dB
 and a jet engine is
about 140 to 180
dB
Hertz – unit of
frequency of sound
waves
 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 16 Hz to 16,000
Hz
 Animals can hear up to
about 50,000 Hz.
Audiogram
 10dB to 25dB = Normal
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
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
hearing
26dB to 40 dB = Mild loss
41 dB to 70 dB = Moderate
71 dB to 90 dB = Severe
over 90 dB =
Profound
Speech Banana
What Causes Hearing Loss?
 Birth defects
 Premature birth
 Illness with high fever
 Meningitis
 Measles
 Scarlet fever
 Medications and
drugs
 Genetic
 Usher syndrome
 Down syndrome
 RH
incompatibility
 Injury to ear
 Loud noises!
 Ear infections
 Injuries to
middle ear
 Head injury
 Old Age