Performance of cochlear implant patients as a function of time.

The speech perception abilities of 15 patients were measured preoperatively using hearing aids and postoperatively using the Nucleus 22-channel cochlear implant over a period of 1, 2, or 3 years. Analysis of mean data revealed that, although the greatest amount of improvement in speech perception scores occurred between the preoperative and 3-month poststimulation evaluation, there was also significant improvement in perception of segmental features and open-set speech recognition over the 3-year time period. When individual patient data were examined, however, it was clear that these improvements were due, in large part, to the performance of a subset of patients who had measurable open-set speech recognition abilities at the time of their 3-month, poststimulation evaluation. Subjects who used the processing scheme that included coding of F1 showed significantly more improvement over time than subjects who used the original F0F2 processing scheme exclusively. It was concluded that open-set speech recognition ability at 3 months is an important prognostic indicator of continued improvement in speech perception abilities over time.