AUDITORY PLASTICITY IN COCHLEAR IMPLANT PATIENTS

Dynamic range (DR) of cochlear implant electrodes and speech recogniti on scores (SRS) were chronologically studied in 23 post-lingually deaf subjects over a period of one year. DR significantly increased over o ne year (ANOVA, p = 0.03). When DR was compared among three groups of electrodes which were located in the inferior, ascending and superior segments of the cochlear basal turn, that in the superior segment show ed the largest increase (p = 0.001), followed by those in the ascendin g and inferior segments. Vowel and consonant recognition scores with a uditory cue were best 6 months after operation and were maintained at that level for one year. Although the time course of improvement diffe red between DR and SRS, a significant positive correlation was observe d at 12 months after operation. Improvement of SRS could be a result o f a DR increase in the superior segment of the cochlea, which should c onvey pitch information over the mid-frequency region.