Download Cochlear Implant

COCHLEAR IMPLANT
BY: SAM SPINK
WHAT IS IT?
• System of external and internal devices that aim to
restore hearing to sensorineural hearing loss patients
• Both pre- and post-lingual hearing loss
• Does not restore functionality to natural cochlea;
stimulates auditory nerve directly
• Restored hearing is not exactly like natural hearing
PROBLEM BEING SOLVED
• Sensorineural hearing loss
• Most common form of hearing loss
• Damage to either brain, auditory nerve, but most commonly
sensory cells of cochlea (cochlear implant used for patients with
this type)
• 1.2 million Americans affected by hearing loss;
sensorineural most common form
• Functioning cochlea: vibrations cause fluid movement,
which is sensed by hair cells of cochlea causing action
potential firing to auditory nerve
• These cells don’t function in those with cochlear implants
CURRENT TECHNOLOGY
• 5 major components
• External devices:
• Microphone-wraps around
front of ear
• Speech processor-behind
ear; attached to microphone
• Transmitter-above processor
• Internal devices:
• Receiver/stimulator-across
from transmitter
• Electrode array-placed on
natural cochlea; wired to
receiver
HOW IT WORKS
• Microphone picks up sound, sends it to speech
processor
• Speech processor filters sound, converts to electrical
signals through fast Fourier Transforms
• Transmitter wirelessly sends signals to
receiver/stimulator
• Receiver/stimulator sends electrical current according to
received signal to electrodes
• Electrodes stimulate auditory nerve
EFFECTIVENESS
• One study shows ability of cochlear implant recipients to
identify sentences over telephone with 82 % success
rate (pre-lingual) and 70% success rate (post-lingual)
• With an adaptor increases to 93% and 88%, respectively
• Speech development in children
• For each 6 month period over first 30 months after receiving
implant, subjects’ increase in “language age” was about double
that of subjects without implants
• Some performed at around same level as non-impaired
LIMITATIONS
• Requires intense therapy post-implantation to achieve
high level of speech comprehension (especially for postlingual patients)
• Device has trouble processing late echoing effects that
go unnoticed by non-impaired ears
• Costs between $45,000 and $125,000
• Surgical complications include infection, facial muscle
weakness, facial paralysis, damaged vestibular system,
loss of all residual hearing
FUTURE DIRECTION
• Improvement in surgical techniques to keep residual
hearing intact
• If cure came about, patients would want what natural hearing still
remained
• Different electrode arrangements
• Longer electrode arrays have shown potential to increase pitch
range
• Variations in electrode spacing at different points on the cochlea
could improve sound quality
REFERENCES
• Hu, Y. and Kokkinakis, K. (2014). Effects of early and late reflections on
intelligibility of reverberated speech by cochlear implant listeners. The Journal of
the Acoustical Society of America, 135(1), pp.22--28.
• Landsberger, D., Mertens, G., Punte, A. and Van De Heyning, P. (2014).
Perceptual changes in place of stimulation with long cochlear implant electrode
arrays. The Journal of the Acoustical Society of America, 135(2), pp.75--81.
• Nidcd.nih.gov, (2014). Cochlear Implants. [online] Available at:
http://www.nidcd.nih.gov/health/hearing/pages/coch.aspx [Accessed 27 Sep.
2014].
• Rigotti, P., Costa, O., Bevilacqua, M., Nascimento, L. and Alvarenga, K. (2013).
Assessment of telephone speech perception in individuals who received
cochlear implant in the period 1993-2003. 25(5), pp.400--406.
• Svirsky, M., Robbins, A., Kirk, K., Pisoni, D. and Miyamoto, R. (2000). Language
development in profoundly deaf children with cochlear implants. Psychological
science, 11(2), pp.153--158.
• Wikipedia, (2014). Cochlear implant. [online] Available at:
http://en.wikipedia.org/wiki/Cochlear_implant [Accessed 27 Sep. 2014].