Speech perception with multi-channel cochlear implant of short duration pulse strategy

A multi-channel cochlear implant (Nucleus type) was implanted in a 40-year-old female Japanese patient who became totally deaf after meningitis. The formant-based speech processing strategy was used, but a narrow pulse width of 22-42 microseconds was required because of intermittent difficulty in controlling the pulse amplitude. The patient was tested with a speech tracking test and could recognize 24 bunsetsues (the minimum meaningful unit of the Japanese sentence) per minute using the cochlear implant plus lipreading and 14.3 bunsetsues for the lipreading alone after 3.5 months' training. The patient was also able to understand usual conversational sentences spoken a little slowly. Scores of vowel and consonant tests reached 70% and 54% respectively for the cochlear implant alone, and 100% and 73% for the cochlear implant plus lipreading. This study has also shown that cochlear stimulation with very narrow pulse widths can be used, and restore speech comprehension ability for the Japanese.