Emergence of a vowel system in a young cochlear implant recipient.

This report chronicles changes in vowel production by a congenitally deaf child who received a multichannel cochlear implant at 19 months. The emergence of Hannah's vowel system was monitored by transcribing vocalic segments from spontaneous utterances produced during two 30-minute recording sessions before implant surgery and 12 monthly recording sessions after her implant was activated. Vowel types were included in her inventory whenever transcribers independently agreed that a vocalization contained an allophone of a given vowel type. Hannah exhibited three vowel types before implantation. A total of nine different vowel types were observed during her first year of implant experience, and a full range of place and height categories was represented. Acoustic analyses revealed that Hannah's vowel space was near normal in size and that the formant structures of /i/ and /u/ were distinctive from other point vowels. Formant regions for /ae/ and /a/ showed some overlap. Taken together with a previous report of her vocal development (D. J. Ertmer & J. A. Mellon, 2001), Hannah appears to have made substantial progress in speech development during her first year of implant use.