Thesis

Quantifying covert contrast in children with velar fronting using ultrasound tongue imaging

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Awarding institution
  • University of Strathclyde
Date of award
  • 2023
Thesis identifier
  • T16570
Person Identifier (Local)
  • 201964328
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Abstract
  • The aim of the present study was to investigate whether school-aged children with SSDs of unknown origin and persistent Velar Fronting showed a covert contrast of a phonetic cause. The present study focused on analysing tongue shapes from UTI to assess motor skills in children with SSDs to determine whether those with persistent velar fronting have a phonetic cause for their errors. The study comprised of participants from a Control Group (CG) and a Study Group (SG), whose tongue shapes during production attempts of /k/ and /t/ were analysed. We expected that evidence of a covert contrast between a child’s /k/ and /t/ tongue shapes would suggest a phonetic cause, rather than a phonological cause for their SSDs. Therefore, perceptually neutralised tokens were compared using t-tests and a measure of spatial difference known as KTmax. The t-test criterion was p ≤ 0.001 along a minimum of seven adjacent radii. The t-test function of AAA was used to test the distance from the origin of a measurement fan to the location of the tongue surface. The KTmax measure, which is also known as the maximum radial difference, indicates the highest degree of separation between tongue splines. Tongue shapes were also visually analysed. Results showed that only one participant in SG (SG_4) demonstrated a covert contrast in non-lexical speech material data (repetitions to nonwords). This participant’s KTmax measure fell within the range of typically developing children’s. However, the same participant did not show a covert contrast in repetitions of single real words. The remaining perceptually persistent velar fronters (4/5) did not show a covert contrast either in non-lexical speech material data or in real word level. The study concludes that some children with persistent velar fronting can show a covert contrast, suggesting phonetic difficulties and that such covert contrast can be measured using UTI.
Advisor / supervisor
  • Kuschmann, Anja
  • Cleland, Joanne, 1980-
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DOI

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