Effects of vowel duration and increasing dynamic spectral information on identification of center-only and edges-only syllables by cochlear-implant users and young normal-hearing listeners

Abstract

In a previous study, cochlear implant (CI) users’ vowel-identification performance was compared to that of young normal-hearing (YNH) listeners. Stimuli included full syllables and two duration-neutralized conditions: center-only and edges-only (silent-center). CI users performed more poorly than YNH listeners overall and showed proportionately larger decrements in performance for partial syllables. Error analyses suggested that at least some CI users rely more heavily on vowel-duration cues than YNH listeners. The present study was designed to test this hypothesis and to determine whether increasing duration of dynamic cues in the edges-only conditions would improve performance, particularly among poorer-performing CI users. Ten YNH listeners and ten adult CI users heard /dVd/ syllables recorded from three talkers. Full syllables were edited to create center-only and edges-only stimuli in which vowel duration cues were or were not preserved, plus edges-only stimuli with different durations of dynamic information. Performance of both groups improved in the duration-preserved condition for center-only, but not edges-only, stimuli. The center-only duration benefit was larger for the CI than for the YNH group. Increasing the duration of dynamic information in the silent-center stimuli improved vowel-identification performance for both groups. Individual differences among CI users and implications for listener-training programs will be discussed.