ELECTRODE DISCRIMINATION BY EARLY-DEAFENED COCHLEAR IMPLANT PATIENTS

Electrode discrimination was measured in six cochlear-implant patients who became profoundly deaf prior to the full development of auditory and speech skills. The cochlear implant manufactured by Cochlear Limit ed was used. Comparisons were made between two electric stimulation pa radigms and two data collection procedures. The paradigms consisted of electrode trajectories and electrodes with random variation in electr ic current levels. The data collection methods consisted of an adaptiv e procedure to obtain difference limens and a method of constant stimu li that gives psychometric functions of discrimination performance. Da ta were collected for reference electrodes at the apical, mid, and bas al positions on the array. The psychometric functions showed that disc rimination performance improved with increases in the spatial separati on between reference and comparison electrodes, The difference limens were similar to the corresponding spatial separation estimated from th e psychometric function in most cases. The discrimination performance of most patients was consistent across the two stimulation paradigms. Difference limens were 13 electrodes from the reference electrode for most patients, There were differences in performance across patients a nd the three positions on the array.