Speaking rate effects on phonemic boundary perception in cochlear implant users

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Rate of speech can affect the durations of certain phonemes (Crystal & House, 1982), and listeners must normalize for speech rate to properly identify words (Miller, 1981). How speech rate affects perception of phonemic boundaries in users of cochlear implants (CIs) in comparison to normal-hearing (NH) listeners is unknown. The speech processing that occurs in these devices may obscure word and phoneme boundaries, providing less reliable durational information about the incoming speech signal. Less effective rate normalization in CI users could thus contribute to the degraded speech perception often observed in this population. Preliminary results with stop-consonant series show absolute differences between NH and CI listeners in the precise location of phonemic boundaries (with CI users’ boundaries typically occurring at shorter voice onset time durations), but not in the relative relationship of these boundaries as a function of speech rate. Data from NH listeners presented a CI simulation show effects of number of channels on both the location of phonemic boundaries and presence of rate normalization.