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Table of Contents
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
Definition: Small, complex electronic Composed of external and internal parts Directly stimulates the auditory nerve Improves hearing
History: Research for device started in 1950s First commercial device approved in mid
1980s
How Normal Hearing Works
Outer ear Captures sound
vibrations Sent to ear cannel then
to middle ear Middle ear
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 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
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
Implant Package Receiver and
Stimulator Antenna Magnet Wire containing
Electrodes Sound and Speech
Processor Mini computer Microphone Transmitter
How a Cochlear Implant Works
Sound is Picked up by Microphone
Converted into Electrical Signals by Sound and Speech
Processor
Signals received by Transmitter
Implant Package determines how
much current passes through to electrodes
Amount of current determines loudness
Position of Electrodes determines Pitch
Nerve Endings in Cochlea Stimulated
Message sent to brain
Signals converted to hearing
Place Theory and Time Theory
Cochlear responds better to a simple tone at one place along its length Sound is separated
into groups Lower pitches Higher Pitches
Use several channels and electrodes spaced out inside the cochlea
Ear Responds to timing of sound Sound signals are
created into pulses Cochlea responds to
different kinds of pulses
Place Theory Time Theory
Implant Surgery
Under General Anesthesia (2-3 Hours)
Incision behind the Ear
Drills a 3-4 millimeter “bed” into Temporal Bone
Opens the Mastoid Bone Access to Middle Ear
Drills a small whole into Cochlea
Implant Surgery Continued
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
Fitting Audiologist attaches headset Align external magnet with the implanted
Implant Check Information is communicated between
implant and external speech processor Every electrode is checked All components are checked
Activation of Cochlear Implant Continued Programming Speech Processor
Electrodes are individually tuned for threshold and comfortable listening levels Electrodes are turned on in small increments
Measure lowest and highest current for electrodes Matches sounds of different electrodes with
different volumes to create a version of sound Creates a Hearing Map
Set of instructions for each electrode on how to stimulate the nerve endings
Rehabilitation
Train brain to understand sounds Initially overwhelmed
Programming sessions Obtain and Maintain optimal performance
Listening Exercises Recognize different sounds
Speech and Language Therapy Identify and interpret sounds
Life After Having a Cochlear Implant
Understand Speech without looking at speaker
Understand Speech with Speech Reading Improved voice
monitoring Improved speech
reading Ability to hear soft
sounds
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.jpghttp://kidshealth.org/PageManager.jsp?
dn=familydoctor&lic=44&cat_id=192&article_set=34740&ps=104#
http://www.mayoclinic.org/cochlear-implants/
http://media3.washingtonpost.com/wp-dyn/content/graphic/2008/04/11/GR2008041102690.jpg
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