Background and Aim: Hearing has an important role in speech production and making phonological distinction, especially voicing distinction. Voice onset time (VOT) has been a reliable acoustic cue of voicing differences in plosive consonants. The purpose of this study was to measure VOT in initial Persian (Farsi) oral plosives produced by cochlear implanted children, comparing to normal hearing children.
Methods: In this cross-sectional study, 20 cases and 20 controls were assessed. Cases were prelingually deaf children who were cochlear implanted 4.5 years prior to test. Controls were normal hearing children at 4.5 years of age. VOT were measured while children uttered oral plosives. The effect of hearing status, voicing, and gender on VOT were assessed.
Results: The amount of VOT of plosives produced by girls was higher than boys, in both groups. This difference was significantly higher in voiceless plosives than in voiced ones. In both groups, voiceless plosives had long-positive VOT value while the amount of VOT was short-positive regarding voiced plosives.
Conclusion: It was demonstrated that VOT is significantly correlated with voicing. In voiceless plosives, VOT could not be considered as a phonetic correlate of hearing status whereas it made significant differences between cochlear implanted children and hearing controls. Furthermore, it was confirmed that concerning voiceless plosives, the amount of VOT of girls was significantly higher than boys. On the contrary, in voiced plosives, gender had no significant effect on the amount of VOT.

Background and Aim: Fundamental frequency (F0) of onset is a reliable acoustic cue of voicing differences in plosive consonants. The purpose of present study was to acoustically analyze of the F0 amount of oral plosive consonants in the initial position of words in cochlear-implanted children and normal hearings.

Methods: In this study, the F0 of onset was measured in the speech production of 47 prelingual deaf children who were cochlear implanted about 61 months before the test (range: 47-76 months, SD: 8.6) and the results were compared with 60 normal hearing children who were 60 months old (range: 49-73, SD: 6.5).

Results: Using repeated measurement tests, it was shown that in all places of articulation, the amount of F0 of onset in voiceless plosives was higher than that of voiced ones, because of the low position of larynx and hyoid bone in voiced plosives. On the other hand, in most cases, the F0 of cochlear-implanted children was lower than that of normal hearings and in voiced plosives, there were significant differences (p=0.005) between cochlear implanted and normal hearing children. There was not any significant difference between the F0 of onset in girls and boys.

Conclusion: In all places of articulation, the mean amount of F0 of onset for voiceless plosives was higher than that of voiced plosives. There was significant difference between F0 of onset in cochlear implanted and normal hearing children.