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cochlear implantation


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cochlear implantation

  1. 2. <ul><li>Presented By- </li></ul><ul><li>Name :Pankaj Kumar Singh (12 ECE 07) </li></ul><ul><li>Univ. Roll No. : - </li></ul><ul><li>Name :Rahul Kumar Singh (09 ECE 07) </li></ul><ul><li>Univ. Roll No. : - </li></ul>
  2. 3. <ul><li>Introduction. </li></ul><ul><li>Anatomy of ear & mechanism of hearing. </li></ul><ul><li>Diseases of ear that results in loss of hearing. </li></ul><ul><li>History of cochlear implants. </li></ul><ul><li>Electronic Cochlea. </li></ul><ul><li>Limitations of cochlear implants. </li></ul><ul><li>Initiatives taken to remove the limitations. </li></ul><ul><li>Conclusions. </li></ul><ul><li>Any Questions? </li></ul>
  3. 4. <ul><li>Definition of cochlea. </li></ul><ul><li>Cochlea as a transducer. </li></ul><ul><li>Cochlear implant as bionic ear </li></ul>Fig: The internal part of a cochlea implant Fig: Cochlea implant as worn by user
  4. 6. <ul><li>Deafness is due to following reasons: </li></ul><ul><li>Bony deposits in the inner ear caused by the aging process. </li></ul><ul><li>Auricle and the opening into the outer auditory canal may be missing at birth. </li></ul><ul><li>Injury to the ear cartilage followed by internal bleeding and excessive production of ear tissue (cauliflower ear). </li></ul><ul><li>Perforation of the eardrum may be caused by injury from a sharp object or by sudden changes in atmospheric pressure. </li></ul><ul><li>Damage to the organ of Corti in the inner ear accounts for the condition of many people who are either totally deaf or severely hearing impaired. </li></ul>
  5. 7. <ul><li>It is a big question .We have hearing aids so why patient should go through operation? </li></ul><ul><li>So here is the difference that we can sort out between the two: </li></ul>Cochlear implants Hearing aids consonants and vowels are understandable Only vowels Unlimited possibilities for signal coding Limited signal coding Surgically implanted No surgery needed 3 batteries or charged battery 1 battery Battery life: 1 to 3 days Battery life: 1 to 2 weeks Success is individual and unpredictable Success is individual and unpredictable Rechargeable Non- rechargeable
  6. 8. The Procedure: <ul><li>Ear Assessment </li></ul><ul><li>Hearing Assessment </li></ul><ul><li>X-Ray Assessment </li></ul><ul><li>Psychological Assessment </li></ul><ul><li>Physical Assessment </li></ul>
  7. 9. <ul><li>THE EARLY YEARS: </li></ul><ul><li>Research during the late 18th and 19th centuries. </li></ul><ul><li>1. 18th century Alessandro Volta discovered Electrolytic cell. </li></ul><ul><li>2. In 1950 Djourno and Charles Eyries Studied using current. </li></ul><ul><li>3. In 1961 ,William House. He developed devices to stimulate acoustic nerves </li></ul>
  8. 10. <ul><li>We hear through the sound analyzing action of the cochlea (inner ear) and the auditory centers of the brain. </li></ul><ul><li>The mechanical-neural transducer of the hearing system is the hair cell, </li></ul>
  9. 11. <ul><li>The cochlear model was described by Lyon. </li></ul><ul><li>He combines a series of filters that model the traveling pressure waves with Half Wave Rectifiers (HWR) to detect the energy in the signal and several stages of </li></ul>Fig: The cochlear model (Lyon)
  10. 12. <ul><li>Parts of the cochlear implant: </li></ul><ul><li>External: </li></ul><ul><li>a microphone </li></ul><ul><li>a speech processor </li></ul><ul><li>a transmitter </li></ul><ul><li>Internal: </li></ul><ul><li>a receiver and stimulator </li></ul><ul><li>an array of up to 22 electrodes wound through the cochlea. </li></ul>
  11. 13. Fig: Floorplan of 100-stage cochlea chip,
  12. 14. Fig: Artist‘s conception of the cochlea Fig: Photomicrograph of 480-stage cochlea test chip.
  13. 15. <ul><li>Processing </li></ul><ul><li>Filter bank strategies use Fast Fourier Transforms. </li></ul><ul><li>Feature extraction strategies used features which are common to all vowels. </li></ul><ul><li>Transmitter </li></ul><ul><li>The transmitter attaches to the receiver using a magnet that holds through the skin. </li></ul><ul><li>It is used to transmit the processed sound information over a radio frequency . </li></ul><ul><li>Receiver </li></ul><ul><li>It receives directions from the speech processor by way of magnetic induction sent from the transmitter. </li></ul><ul><li>receiver is also a sophisticated computer . </li></ul><ul><li>It is embedded in the skull behind the ear. </li></ul>
  14. 16. <ul><li>Electrode array </li></ul><ul><li>The electrode array is made from a type of silicone rubber. </li></ul><ul><li>The electrodes are platinum or a similarly highly conductive material. </li></ul><ul><li>The mean length of human being cochlea is 33–36 mm. </li></ul><ul><li>22 array electrodes within the cochlea and 2 extra-cochlear electrodes (ground). </li></ul><ul><li>Speech processors </li></ul><ul><li>It transforms the sounds picked up by the microphone into electronic signals . </li></ul><ul><li>There are primarily two forms of speech processors available </li></ul><ul><li>Programming the speech processor </li></ul><ul><li>The cochlear implant must be programmed individually for each user. </li></ul><ul><li>The programming is performed by an audiologist trained to work with cochlear implants. </li></ul>
  15. 17. <ul><li>Damage to nerve cells within the cochlea </li></ul><ul><li>It is not as good as the quality of sound processed by a natural cochlea. </li></ul><ul><li>VLSI technology limitations such as threshold variation </li></ul><ul><li>present an important challenge in designing systems with appropriate collective behavior. </li></ul><ul><li>Outer hair cells provide active and adaptive undamping to boost weak sounds and attenuate loud ones, there by providing the gain-control element of an AGC loop. </li></ul><ul><li>The key problems in sound perception are to cope with a very wide dynamic range of loudness and to separate sounds on the basis of their properties, such as frequency content and time structure. </li></ul>
  16. 19. <ul><li>The problems we must solve to build perception machines are mostly similar to those that nature had to solve biologically in the evolution of intelligent animal behavior. </li></ul>