Effects of Age on Voice Onset Time and Variability in Children with Repaired Cleft Palate

Abstract

Objective: To examine the effect of age on voice onset time (VOT) and VOT variability in children with repaired cleft palate. Methods: Twenty-two children with repaired cleft palate were allocated into two age groups: younger children (YC: n = 13) and older children (OC: n = 9). VOT measurements from monosyllabic words (/pɑ/, /tɑ/, and /kɑ/) and intraspeaker VOT variability estimated by coefficients of variation (CoV) of two age groups were compared. Results: Age was found to have a statistically significant effect on VOT and VOT variability. Specifically, OC had significantly longer VOT (F(1,66) = 4.196, p < 0.05) and less VOT variability (F(1,66) = 6.007, p < 0.05) for English voiceless stops than YC. No statistically significant main effect for speech sample or age by speech sample interaction was observed. Conclusions: Our data supplement the existing literature by adding VOT and VOT variability information for older children/adolescents with repaired cleft palate. Findings from the study suggest VOT patterns acquired at younger age appear to be further exaggerated and stabilized during the adolescent period among children with repaired cleft palate. A future study is necessary to determine different sources of VOT variability in children with a history of cleft palate, which may have clinical therapeutic implications.