Vowel production in a prelinguistic child following cochlear implantation.

Formant frequencies were determined from vocalic utterances of a prelinguistically deafened child implanted with a Nucleus 22-channel device at age 5 years. Speech samples were obtained from recordings of speech made 5 and 2 months prior to implantation and at 6, 12, 18, 24, and 36 months post implantation. Prior to implantation, first formant values showed a greater range than those of normal hearing children of comparable age, and second formant values showed a greatly reduced range and clustered around a mean of 1800 Hz. By 36 months post implantation, first formant values approximated age-matched norms. By 6 months post implantation, higher second formant values were apparent. A progressive shift in second formant values was noted through 36 months post implantation when the vocalic space most closely corresponded to age-matched normative data.