Although the spectrally degraded input provided by cochlear implants (CIs) is sufficient for speech perception in quiet, it poses problems for talker identification. The present study examined the ability of normally hearing (NH) children and child CI users to recognize cartoon voices while listening to spectrally degraded speech.
In Experiment 1, 5- to 6-year-old NH children were required to identify familiar cartoon characters in a three-alternative, forced-choice task without feedback. Children heard sentence-length utterances at six levels of spectral degradation (noise-vocoded utterances with 4, 8, 12, 16, and 24 frequency bands and the original or unprocessed stimuli). In Experiment 2, child CI users 4 to 7 years of age and a control sample of 4- to 5-year-old NH children were required to identify the unprocessed stimuli from Experiment 1.
NH children in Experiment 1 identified the voices significantly above chance levels, and they performed more accurately with increasing spectral information. Practice with stimuli that had greater spectral information facilitated performance on subsequent stimuli with lesser spectral information. In Experiment 2, child CI users successfully recognized the cartoon voices with slightly lower accuracy (0.90 proportion correct) than NH peers who listened to unprocessed utterances (0.97 proportion correct).
The findings indicate that both NH children and child CI users can identify cartoon voices under conditions of severe spectral degradation. In such circumstances, children may rely on talker-specific phonetic detail to distinguish one talker from another.