This study evaluated 20 deaf adults' ability to understand connected discourse under two conditions: (a) lipreading alone (LA), and (b) lipreading plus electrical stimulation by a single-channel cochlear implant (LI). Performance was evaluated using the speech-tracking procedure, which required the deaf receiver to repeat verbatim textual material read by another individual. The reception of ongoing speech was measured in terms of the number of words repeated correctly per minute. The results revealed, on the average, a significantly higher tracking rate in the LI condition (28.6 wpm) than the LA condition (16.4 wpm). There was a significant learning effect across sessions for both conditions. Subjects who were previous hearing aid users achieved a significantly higher tracking rate in the LI condition than did subjects who had no previous experience with amplification. Significant subject differences were present as a function of condition. Sixteen of the 20 subjects achieved higher tracking rates in the LI than in the LA condition. However, 4 of these 16 subjects showed similar relative gains in both conditions and 3 showed a decrease in performance in the LA condition over time. The remaining 4 subjects showed nearly equivalent tracking rates in both conditions over time. The data suggest that the majority of subjects were able to learn to make use of the cues provided by electrical stimulation by a single-channel cochlear implant to enhance their lipreading skills, at least for highly redundant material in a communicative situation.
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