1. COCHLEAR IMPLANTS Brittany M. Alphonse Biomedical Engineering BME 181

2. 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

3. 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

4. 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

5. 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

6. 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

7. Parts of a Cochlear Implant  Implant Package  Receiver and Stimulator  Antenna  Magnet  Wire containing Electrodes  Sound and Speech Processor  Mini computer  Microphone  Transmitter

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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/wp- dyn/content/graphic/2008/04/11/GR20080411 02690.jpg