Voice onset time of Afrikaans speaking children aged four to seven years

The scarcity of developmental voice onset time (VOT) data for pre-school children of different languages, limits deductions regarding the influence of linguistic and age factors on VOT. Expanded developmental VOT-data are of diagnostic value in comparing normal and disordered speech and language in various populations. The purpose of this study was to obtain normative, acoustic information regarding the nature of VOT of voiced and voiceless Afrikaans stops in ten children, ranging in age from 4.0-7.0 years. VOT-measurements were made from wide-band spectrograms, using the Kay digital signal processing sonagraph, model 5500. A multi-subject case study design was used and results are described both qualitatively and quantitatively. Individual mean VOT's for voiced stop contexts ranged from -97-+12ms. Four-year-olds displayed voicing lead in 27% of their mean VOT-values, five-year-olds 4% and six-year-olds 80%. Individual mean VOT-values for voiceless stop contexts ranged from +11-+37ms with very similar performance across age groups. All age groups showed overlapping VOT-values for voiced and voiceless stops (i.e. in the short lag voicing category). Results indicated possible differences between the developmental patterns of VOT in Afrikaans and English.