Extending ultrasound tongue shape complexity measures to speech development and disorders

Heather Kabakoff, Daphna Harel, Mark Tiede, D. H. Whalen, Tara McAllister

Research output: Contribution to journalArticlepeer-review


Purpose: Generalizations can be made about the order in which speech sounds are added to a child’s phonemic inventory and the ways that child speech deviates from adult targets in a given language. Developmental and disordered speech patterns are presumed to reflect differences in both phonological knowledge and skilled motor control, but the relative contribution of motor control remains unknown. The ability to differentially control anterior versus posterior regions of the tongue increases with age, and thus, complexity of tongue shapes is believed to reflect an individual’s capacity for skilled motor control of speech structures. Method: The current study explored the relationship between tongue complexity and phonemic development in children (ages 4–6 years) with and without speech sound disorder producing various phonemes. Using established metrics of tongue complexity derived from ultrasound images, we tested whether tongue complexity incrementally increased with age in typical development, whether tongue complexity differed between children with and without speech sound disorder, and whether tongue complexity differed based on perceptually rated accuracy (correct vs. incorrect) for late-developing phonemes in both diagnostic groups. Results: Contrary to hypothesis, age was not significantly associated with tongue complexity in our typical child sample, with the exception of one association between age and complexity of /t/ for one measure. Phoneme was a significant predictor of tongue complexity, and typically developing children had more complex tongue shapes for /ɹ/ than children with speech sound disorder. Those /ɹ/ tokens that were rated as perceptually correct had higher tongue complexity than the incorrect tokens, independent of diagnostic classification. Conclusions: Quantification of tongue complexity can provide a window into articulatory patterns characterizing children’s speech development, including differences that are perceptually covert. With the increasing availability of ultrasound imaging, these measures could help identify individuals with a prominent motor component to their speech sound disorder and could help match those individuals with a corresponding motor-based treatment approach.

Original languageEnglish (US)
Pages (from-to)2557-2574
Number of pages18
JournalJournal of Speech, Language, and Hearing Research
Issue number7
StatePublished - Jul 2021


  • Adult
  • Child
  • Child, Preschool
  • Humans
  • Phonetics
  • Speech
  • Speech Production Measurement
  • Speech Sound Disorder/diagnostic imaging
  • Tongue/diagnostic imaging
  • Ultrasonography

ASJC Scopus subject areas

  • Speech and Hearing
  • Language and Linguistics
  • Linguistics and Language


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