Efficacy of the discreteness of voicing category (DOVC) measure for characterizing voicing errors in children with cochlear implants: a report.

PURPOSE: This investigation explored the utility of an acoustic measure, called the discreteness of voicing category (DOVC), in identifying voicing errors in stop consonants produced by children with cochlear implants. Another objective was to examine the perceptual relevance of the DOVC measure and 2 commonly used voice onset time (VOT)-based measures, namely, mean VOT and DeltaVOT (e.g., VOT /t/-VOT /d/). METHOD: Phonetic transcription and acoustic analyses were carried out on syllable-initial /t / and /d/ produced by 10 children with cochlear implants. The DOVC was calculated as the difference between the shortest VOT value of a voiceless stop and the longest VOT value of a voiced stop across several productions of each. RESULTS: Phonetic transcription revealed that 4 of the 10 talkers demonstrated atypical voicing distinctions. Acoustic analyses indicated that the DOVC measure identified these same 4 talkers as producing atypical values, whereas mean VOT and DeltaVOT identified a different set of talkers as demonstrating values outside the normal ranges. CONCLUSION: Preliminary findings suggest that the DOVC measure corresponded with perceptual data better than the other acoustic measures examined in the present study. Data indicate that the DOVC measure may provide perceptually relevant information concerning the production of voicing distinctions.

Effects of auditory feedback deprivation length on the vowel /epsilon/ produced by pediatric cochlear-implant users.

Effects of auditory deprivation on speech production by ten cochlear-implanted children were investigated by turning off the implant for durations ranging from 0.3 to 5.0 s and measuring the formant frequencies (F1 and F2) of the vowel /epsilon/. In five of the ten talkers, F1 and/or F2 shifted when auditory feedback was eliminated. Without feedback, F2 frequency lowered consistently, suggesting vowel centralization. Phonetic transcription indicated that some of these acoustic changes led to perceptible shifts in phonetic quality. The results provide evidence that brief periods of auditory deprivation can produce perceptible changes in vowels produced by some cochlear-implanted children.