Transcript Cochlear Implants - Electrical, Computer & Biomedical Engineering

COCHLEAR IMPLANTS
BME 181
Brittany M. Alphonse
Biomedical Engineering
Table of Contents
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Definition and History of Cochlear Implants
How Normal Hearing Works
Reasons for a Cochlear Implant
Parts of a Cochlear Implant
How a Cochlear Implant Works
Place Theory and Time Theory
Implant Surgery
Activation of Cochlear Implant
Rehabilitation
Life After Having a Cochlear Implant
Definition and History of Cochlear Implants
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Definition:
 Small,
complex electronic
 Composed of external and internal parts
 Directly stimulates the auditory nerve
 Improves hearing
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History:
 Research
for device started in 1950s
 First commercial device approved in mid 1980s
How Normal Hearing Works
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Outer ear
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Captures sound vibrations
Sent to ear cannel then to
middle ear
Middle ear
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Vibration cause the bones to
move
Bones cause the fluid in
Cochlea to move
Fluid movement stimulates hair
cells
Hairs move back and forth
sending electrical signals to
auditory nerve
Carried to the brain
How Normal Hearing Works Continued
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Cochlea
 Snail
shaped or curled
tube in the part of the
ear where the nerves
are contained
 Gathers electrical
signals from sound
vibration
 Transmits to auditory
nerve
Reasons for a Cochlear Implant
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Hearing Aids only amplify sound
Restore or regain ability to sense sound for those
who have experience significant hearing loss
Hearing loss due to infections of the ear
Profound deafness
Problems with the inner ear or cochlea
 Parts
of the cochlea are not working the right way
 Auditory
nerve isn’t stimulated
 Nerve deafness or sensorineural hearing loss
Parts of a Cochlear Implant
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Implant Package
Receiver and Stimulator
 Antenna
 Magnet
 Wire containing
Electrodes
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Sound and Speech
Processor
Mini computer
 Microphone
 Transmitter
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How a Cochlear Implant Works
Sound is Picked up by
Microphone
Amount of current determines
loudness
Converted into Electrical
Signals by Sound and
Speech Processor
Position of Electrodes
determines Pitch
Signals received by
Transmitter
Implant Package determines
how much current passes
through to electrodes
Nerve Endings in Cochlea
Stimulated
Message sent to brain
Signals converted to hearing
Place Theory and Time Theory
Place Theory
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Cochlear responds better
to a simple tone at one
place along its length
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Sound is separated into
groups
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Lower pitches
Higher Pitches
Use several channels and
electrodes spaced out
inside the cochlea
Time Theory
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Ear Responds to timing of
sound
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Sound signals are created
into pulses
Cochlea responds to
different kinds of pulses
Implant Surgery
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Under General
Anesthesia (2-3 Hours)
Incision behind the Ear
Drills a 3-4 millimeter
“bed” into Temporal
Bone
Opens the Mastoid Bone
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Access to Middle Ear
Drills a small whole into
Cochlea
Implant Surgery Continued
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Threads wires of
Electrodes into spirals
of Cochlea
Receiver is implanted
in skull
Implant Package is
secured
Incision is closed
Most leave after
surgery
Activation of Cochlear Implant
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Fitting
 Audiologist
attaches headset
 Align external magnet with the implanted
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Implant Check
 Information
is communicated between implant and
external speech processor
 Every electrode is checked
 All components are checked
Activation of Cochlear Implant Continued
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Programming Speech Processor
 Electrodes
are individually tuned for threshold and
comfortable listening levels
 Electrodes
 Measure
are turned on in small increments
lowest and highest current for electrodes
 Matches
sounds of different electrodes with different
volumes to create a version of sound
 Creates
 Set
a Hearing Map
of instructions for each electrode on how to stimulate the
nerve endings
Rehabilitation
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Train brain to understand sounds
 Initially
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Programming sessions
 Obtain
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overwhelmed
and Maintain optimal performance
Listening Exercises
 Recognize
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different sounds
Speech and Language Therapy
 Identify
and interpret sounds
Life After Having a Cochlear Implant
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Understand Speech
without looking at
speaker
Understand Speech
with Speech Reading
 Improved
voice
monitoring
 Improved speech
reading
 Ability to hear soft
sounds
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Success Rates:
 Auditory
Memory
 Number of functioning
Auditory Nerve Fibers
in Cochlea
 How long been Deaf
 Ability to Speak
before Hearing loss
 Age
 Continued therapy and
programming sessions
References for Pictures
http://www.hearingclinic.net.au/mhc/content/the_ear.
php
http://universe-revie w.ca/I10-85-cochlea.jpg
http://kidshealth.org/PageManager.jsp?dn=familydo
ctor&lic=44&cat_id=192&article_set=34740&ps=
104#
http://www.mayoclinic.org/cochlear-implants/
http://media3.washingtonpost.com/wpdyn/content/graphic/2008/04/11/GR20080411
02690.jpg