|
Before going into details of how a cochlear
implant works, it is important to understand the structure of the ear
and how it works.
Sound waves enter the ear canal and
impact the ear drum (typmanic membrane). After the ear drum picks up the
sound, it transmits sound wave vibrations through the hammer (malleus),
anvil (incus), and stirrup (stapes). The hammer, anvil, and stirrup make
up the chain of three (3) middle ear bones. The stirrup passes the
vibrations to the inner ear fluids within the cochlea. Fluid waves
travel through two and a half (2½) turns of the cochlea, bending the
cochlea hair cells as it goes by. The hair cells correspond to the
frequency of the original sound waves, initiating signals within their
corresponding nerve endings prior to sending them to the brain.
A multichannel cochlear implant is an
electronic device developed to restore auditory sensation through
electrical stimulation of the auditory nerve for individuals age 12
months and older with severe to profound sensorineural hearing
impairment. The stimulation provides a wide range of auditory
information needed for recognizing environmental and speech sounds to
expand communication ability.
A cochlear implant is designed to bypass
damaged or degenerating cochlear hair cells (within the inner ear that
correspond to the sound wave frequencies). The hair
cells are the "spark plugs" of the inner ear nerve endings.
The vast majority of nerve deafness is usually the result of
non-functioning hair cells, however, with the nerve endings still purposeful
in the majority of those cases, it makes it possible for cochlear
implants to work.
|
