A 4-year investigation into phonetic inventory development in young cochlear implant users

Phonetic inventories of 9 children with profoundly impaired hearing who use d the 22-electrode cochlear implant (Cochlear Limited) were monitored befor e implantation and during the first 4 years of implant use. All children we re 5 years old or younger at the time of implant. Spontaneous speech sample s were collected at regular intervals for each child and analyzed to invest igate phone acquisition over the post-implant period. Acquisition was measu red using two different criteria. The "targetless" criterion required the c hild to produce a phonetically recognizable sound spontaneously, and the "t arget" criterion required the child to produce the phone correctly at least 50% of the time in meaningful words. At 4 years post-implant, 40 out of 44 phones (91%) had reached the targetless criterion, and 29 phones (66%) had reached the target criterion for 5 or more of the children. Over the time of the study 100% of monophthongs, 63% of diphthongs, and 54% of consonants reached the target criterion. The average time taken For a phone to progre ss From the targetless to target criterion was 15 months. Overall, the data suggest trends in the order of phone acquisition similar to those of norma lly hearing children, although the process of acquisition occurred at a slo wer rate.