Coarticulation, one of the central issues in experimental phonetic research, refers to the articulatory overlap of neighbouring sounds, resulting in acoustic and perceptual modifications of these sounds. Studies of the development of coarticulatory patterns in children have produced conflicting results concerning adult-child differences. This research compares coarticulatory properties of speech in children and adults, using innovative articulatory measures derived from ultrasound imaging. The aims are to establish how children's patterns of coarticulation differ from adults', and to attempt to explain the observed coarticulatory patterns, as well as the nature and the degree of variability found in adults and children.Synchronised ultrasound and acoustic data will be recorded using the Queen Margaret University ultrasound system. Consonant-vowel syllables in real sentences will be produced by ten normally developing children aged 7 years, and ten adults, all speakers of Standard Scottish English. Child and adult productions will be compared according to an ultrasound-based measure of coarticulation, and any significant differences in amount of coarticulation and degree of within-speaker variability will be established. Qualitative examination of individual variation will help to establish the nature of any differences between children and adults in the organisational structure of speech in terms of segments, syllables and words.

Data collection method: recordings of participants' voices and tongue movements in a sound-treated studio. Synchronised ultrasound and acoustic data were collected using the Queen Margaret University ultrasound system. The system includes customised software designed for recording, playback and analysis of synchronised ultrasound and acoustic data, Articulate Assistant Advanced (Ultrasound Module), produced by Articulate Instruments Ltd, www.articulateinstruments.com.