A cochlear implant is an electronic device placed under the skin to carry sound, bypassing the damaged parts of the ear, to stimulate the hearing nerve, which in turn carries those signals to brain for understanding.
Parts of Cochlear Implants:
A microphone, which picks up sound from the environment.
A speech processor, which selects and arranges sounds picked up by the microphone.
A transmitter and receiver/stimulator, which receives signals from the speech processor and converts them into electric impulses.
An electrode array, which is a group of electrodes that collects the impulses from the stimulator and sends them to different regions of the auditory nerve.
How does a cochlear implant work?
The external components capture environmental sounds as well as speech and music.
They process the sound so that it can be transmitted across the skin to the implant. The implant then passes the signals to the electrode array.
Individual electrodes deliver these signals to the hearing nerve.
Who requires cochlear implants?
Anyone who is suffering with severe to profound deafness, which means not being able to hear sound stronger than 90 dB HL at a frequency of 2 – 4 kHz (a measuring unit of intensity of sound) will need cochlear implants.
Apart from assessing functional hearing ability, a thorough assessment is also done by a multidisciplinary team before surgery to determine fitness for surgery and the ability of the person to derive benefit from a cochlear implant system.
Individuals 18 years of age or older.
Moderate to profound hearing loss in both ears.
Limited benefit from amplification defined by preoperative test scores of ≤50% sentence recognition in the ear to be implanted and ≤60% in the opposite ear or binaural.
Severe to profound hearing loss.
Limited benefit from binaural amplification.
Multisyllabic Lexical Neighborhood Test (MLNT) or Lexical Neighborhood Test(LNT) scores ≤ 30%.
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