Voice Onset Time (VOT) in Kannada Speaking Children with Cleft Palate: A Pre- and Post-Operative Comparison

Abstract

Background and Objective :The speech of children with cleft lip and palate (CLP) is characterized by lack of abnormal intraoral pressure which leads to misarticulation of pressure consonants. This often results in unintelligible speech due to variable voice onset time (VOT) in pressure consonants. Surgical procedures and speech therapy have often been found to bring adequate changes in the acoustic parameters in the speech of children with CLP. Hence the aim of the present study was to investigate the changes in VOT in children with CLP in the pre and post operative condition and to compare with typically developing children.Method:The study included subjects in Group I consisted of five children with unrepaired CLP and palate who underwent surgery later (group II) and group III consisted of age and gender matched typically developing children with normal oro-facial structures. All the subjects were native speakers of Kannada language (a Dravidian language spoken in south India) and were in the age range of 5 -14 years. Eight Kannada meaningful bisyllabic words loaded with stop consonants (/p/, /?/, /k/, /b/, /?/, and /g/) in CVCV combination were selected as stimuli and these words were repeated by the children, which were audio recorded and acoustically analyzed using Praat software.Results:The VOT data was subjected to statistical analysis to compare the changes across and within group. Results showed that VOT in children with CLP was longer in the pre operative conditions compared to that of the control group and VOT in post-operative condition was longer compared to the VOT in pre-operative condition. The results also explore the differences in VOT for pressure consonants based on place/manner of articulation.Conclusions:The present study highlights the influence of the surgical correction of the palate on the acoustic characteristics and facilitates understanding the physiological changes in the oropharyngeal system.