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COCHLEAR IMPLANTS Brittany M. Alphonse Biomedical Engineering BME 181

COCHLEAR IMPLANTS Brittany M. Alphonse Biomedical Engineering BME 181

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COCHLEAR IMPLANTSBrittany M. Alphonse Biomedical Engineering

BME 181

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