The contribution of phonetic and contextual information in speech perception by cochlear implant wearers.

摘要

In this investigation, the speech perception of cochlear implant wearers who are and are not able to perceive open-set (unpracticed, unfamiliar words and sentences) speech when using hearing alone was evaluated and compared. The purpose of this study was to determine if differences in ability to perceive open-set speech with a cochlear implant is related to the listener's ability to utilize various speech perception cues. Investigation of phoneme, word, and sentence perception skills revealed that open-set listeners recognize signficantly more phonemes, words, and sentences than do non open-set listeners. However, greater differences existed between the two groups at the word/sentence level than at the phoneme level, indicating that open-set listeners are better able to utilize syllable and word context than are non open-set listeners. A gating task was used to examine the relationship between open-set speech perception and ability to utilize sentence context and revealed that open-set listeners derive more benefit from highly predictable sentence contexts than do non open-set listeners. The third part of the study provided additional evidence regarding open-set listeners' enhanced utilization of context. In this part of the study, listeners' recognition of phonetically sparse (synthetically-produced) speech was compared to recognition of phonetically intact (naturally-produced) speech. When the two groups perceived similar amounts of acoustic-phonetic information (i.e. when they demonstrated similar phoneme recognition scores), the open-set listeners continued to recognize more sentence stimuli than the non open-set listeners. In summary, this study provides converging evidence that open-set implant-wearing listeners are better able to utilize context to perceive speech than are non open-set listeners.