Acoustic Simulations of Cochlear Implants
Cochlear implant patient's level of performance may vary from 0% to 100% correct on speech recognition tasks.
It is not surprising that there is a large variance in speech performance
among implant patients given the many factors that
may affect their performance. Unfortunately, it is not easy to assess the
individual factors (e.g., neuron survival, electrode insertion depth, etc.) on speech perception due to the interaction among
How can we isolate the effect of electrode insertion
depth, or any other factor, on speech performance assuming that
all other factors are held equal?
As a first step towards assessing the effect of various factors on
performance, Dr. Loizou and Dr. Michael Dorman (from Arizona State University) used acoustic
simulations of cochlear implants. In these simulations, speech was
processed in a manner similar to the implant processor and output
as a sum of sinusoids . The reconstructed speech was
presented to normal-hearing listeners for identification. Several set of experiments were conducted that examined:
- the number of channels necessary for achieving high-levels of speech
- the effect of electrode insertion depth on
auditory performance (listening demo),
- the effect of reduced (electrode) dynamic range on
M. Dorman, P. Loizou and D. Rainey (1997). "Speech intelligibility as a function of the number of channels of stimulation for signal processors using sine-wave and noise-band outputs," Journal of Acoustical Society of America,
M. Dorman, P. Loizou and D. Rainey (1997). "Simulating the effect of cochlear-implant electrode insertion depth on speech understanding," Journal of Acoustical Society of America, 102(5), 2993-2996.