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 significance of individual factors (e.g., neuron survival, electrode insertion depth, etc.) on speech perception due to the interaction among factors. 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 auditory 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:

Related publications:

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, 102(4), 2403-2411.

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.