LEXICAL EFFECTS ON SPOKEN WORD RECOGNITION BY PEDIATRIC COCHLEAR IMPLANT USERS

Objective: The purposes of this study were 1) to examine the effect of lexical characteristics on the spoken word recognition performance of children who use a multichannel cochlear implant (CI), and 2) to comp are their performance on lexically controlled word lists with their pe rformance on a traditional test of word recognition, the PB-K. Design: In two different experiments, 14 to 19 pediatric CI users who demonst rated at least some open-set speech recognition served as subjects. Ba sed on computational analyses, word lists were constructed to allow sy stematic examination of the effects of word frequency, lexical density (i.e., the number of phonemically similar words, or neighbors), and w ord length. The subjects' performance on these new tests and the PB-K also was compared. Results: The percentage of words correctly identifi ed was significantly higher for lexically ''easy'' words (high frequen cy words with few neighbors) than for ''hard'' words (low frequency wo rds with many neighbors), but there was no lexical effect on phoneme r ecognition scores. Word recognition performance was consistently highe r on the lexically controlled lists than on the PB-K. In addition, wor d recognition was better for multisyllabic than for monosyllabic stimu li. Conclusions: These results demonstrate that pediatric cochlear imp lant users are sensitive to the acoustic-phonetic similarities among w ords, that they organize words into similarity neighborhoods in long-t erm memory, and that they use this structural information in recognizi ng isolated words. The results further suggest that the PB-K underesti mates these subjects' spoken word recognition.