| 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. |
