Speech changes following reimplantation from a single-channel to a multichannel cochlear implant.

The speech of a postlingually deafened preadolescent was recorded and analyzed while a single-electrode cochlear implant (3M/House) was in operation, on two occasions after it failed (1 day and 18 days) and on three occasions after stimulation of a multichannel cochlear implant (Nucleus 22) (1 day, 6 months, and 1 year). Listeners judged 3M/House tokens to be the most normal until the subject had one year's experience with the Nucleus device. Spectrograms showed less aspiration, better formant definition and longer final frication and closure duration post-Nucleus stimulation (6 MO. NUCLEUS and 1 YEAR NUCLEUS) relative to the 3M/House and no auditory feedback conditions. Acoustic measurements after loss of auditory feedback (1 DAY FAIL and 18 DAYS FAIL) indicated a constriction of vowel space. Appropriately higher fundamental frequency for stressed than unstressed syllables, an expansion of vowel space and improvement in some aspects of production of voicing, manner and place of articulation were noted one year post-Nucleus stimulation. Loss of auditory feedback results are related to the literature on the effects of postlingual deafness on speech. Nucleus and 3M/House effects on speech are discussed in terms of speech production studies of single-electrode and multichannel patients.