The development of speech production following cochlear implantation

Conversational speech samples were analysed over a six-year period postoper atively for nine profoundly deaf children implanted with the Cochlear Limit ed 22-electrode cochlear implant between ages 2-5 years. Four years post-im plant, at least 90% of all syllables produced by each child were intelligib le, although only one of the children (who had suffered a progressive heari ng loss) had over 10% intelligible syllables Drier to implantation. Over th e B-year period, the mean number of intelligible words per utterance increa sed from 0.15 to 4.2 and the mean number of syllables (counting both intell igible and unintelligible syllables) increased from 1.7 to 5.2, indicating an increase in complexity as well as intelligibility. The speech samples we re transcribed phonetically and percentage correct analyses were conducted on the transcripts. These analyses showed a steady improvement in the perce ntage of correctly produced monophthongs, diphthongs and consonants. There was a corresponding rise in the percentage of words that were produced with out phonetic errors, Following six years of implantation, the speech acquis ition process was incomplete, although there was no evidence to suggest a p lateau in performance.