Coarticulation and tongue differentiation in children between three and thirteen years old

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When children learn to speak, by the age of three years old they typically produce most vowels and consonants correctly. However many details, particularly those concerned with complex variations of speech sound production in words and sentences (or coarticulation), continue to develop during childhood. An example of coarticulation is the difference between two realisations of the consonant /s/, in the words "sea" and "saw", which arises from the influence of the following vowel. Understanding of coarticulatory processes and the constraints on them (for example the ability to differentiate between parts of the tongue, addressed in this project) is fundamental to our knowledge of the general processes of speech motor control. There are a number of applications of this knowledge, particularly for theories of child development, and also for assessment and treatment of speech disorders. Much remains unknown on the precise course of the development of tongue control during childhood. This project will investigate speech motor skills maturation, by collecting and analysing ultrasound imaging data on tongue position and shape in speech, in six age groups between 3 and 13 years old.The study will provide data on lingual coarticulatory patterns with limits of variation acceptable for children and adolescents with non-disordered speech motor skills. Ultrasound tongue imaging is a safe and non-invasive technique, and it produces information about the shape of most of the midsagittal tongue contour, including the root of the tongue. The project will build on previous ESRC-funded studies carried out by the lead applicant, where productions of children, preadolescents and adults were compared, but age groups were not as tightly defined as in the proposed study. In the new project, we will focus on the subtle developmental changes which our previous research has suggested are likely to be found during childhood. The recording and analysis protocol has been refined in previous studies, and a method of comparing tongue curves was developed, which does not require head-to-transducer stabilisation, and thus enables us to analyse data from 3- and 5-year-olds. In the course of the project, this method will be validated, and will be available for future studies.Based on the results of the study, we will propose a theoretical view on the role of tongue constraints in the development of coarticulation. The database collected in the project will be a resource for addressing further aspects of coarticulation development and other linguistic phonetic questions. The results will be disseminated at international and UK conferences and seminars, including a two-day international symposium on coarticulation development, which will be organised in Edinburgh during the project. The database of synchronised ultrasound and acoustic data will be made available to researchers, university students and non-academic professionals. Articles will be submitted for publication in international peer-reviewed journals, continuing a successful and influential thread of research. For engaging with potential participants, a research information day will be held at the onset of the project, to introduce children and their parents and carers to the experimental technique. At the end of the project, another research information day will be organised for the project participants, university students and professionals, to discuss the results of the project. The use of ultrasound scanners for imaging and interpreting tongue movements will be demonstrated, and potential applications to therapy and language teaching will be discussed. Two study days for speech and language therapists will be held throughout the project, as well as a clinically oriented workshop within the international symposium. The results will be disseminated via a dedicated website, electronic newsletters, and through publishing in professional journals and popular magazines read by the general public.