Tongue shape complexity in children with speech sound disorders

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Purpose This study investigates the hypothesis that younger speakers and speakers with more severe speech sound disorders (SSD) are more likely to use undifferentiated tongue gestures due to difficulties with lingual motor control (Gibbon 1999). Kabakoff et al. (2021) measured the number of tongue inflections (NINFL) using ultrasound tongue imaging (UTI) and showed that children with SSD have lower tongue complexity when producing /ɹ/ than typically developing (TD) children. They also reported that younger children had higher complexity for /t/ than older children.
Method Children with idiopathic SSD (n=23, aged 5;2-12;11) and without SSD (n=24, aged 5;8-12;11) had high-speed ultrasound and audio recordings made by a Speech and Language Therapist. The children with SSD produced 10 repetitions of /p, t, k, j, ɹ, l, w, s, θ, ʃ/ an /aCa/ environment and those without SSD produced one repetition. Percent tokens correct (PTC) per consonant were measured by a Speech and Language Therapist using ultrasound and audio recordings and used as proxy for the severity of the SSD for that consonant. PTC of the TD children was 100% throughout. NINFL was measured
automatically using AAA software after fitting tongue splines at the point of maximal lingual gesture. A mixed effects ordinal regression model was used for analysis: NINFL (range:1 to 5) ~ Age (in months, scaled)*PTC (scaled)*Consonant (baseline /p/) + (1 + Consonant (baseline /p/) | Speaker).
Results There were significant effects of Age, PTC, and Consonant (for /j/ and /t/ compared to /p/). For average age and PTC, /t/ had lower NINFL than /p/ and /j/ had higher NINFL. There was a significant interaction between Age and PTC for baseline /p/. There was a significant interaction between Age and Consonant for average PTC. For children with average PTC, increase in age led to increase in NINFL for /p/ but not as steep of an increase for /w/, /ɹ/, /ʃ/ and /s/.
There was a significant interaction between PTC and Consonant. For average-aged children in the sample, an increase in PTC led to an increase in NINFL for /ɹ/, /ʃ/, /s/, /θ/, /t/ compared to /p/. Lastly, there was a significant triple interaction between Age, PTC, and Consonant. Increase in age and PTC led to increasing NINFL for /ɹ/, /ʃ/, /s/, /θ/ compared to /p/. The raw data is illustrated in Figures 1 and 2.
Conclusions The significant interactions between age, severity of the specific sound distortion and consonant suggest that “correct” realisations of sounds may involve different levels of tongue complexity across ages depending on phoneme. Increase in age and accuracy of productions led to increase in lingual complexity in some circumstances for /ɹ/, /ʃ/, /s/, /θ/, /t/, supporting the initial hypothesis.
References Gibbon, F. E. (1999). Undifferentiated Lingual Gestures in Children With Articulation/Phonological Disorders. Journal of Speech, Language, and Hearing Research, 42(2), 382–397. Kabakoff, H., Harel, D., Tiede, M., Whalen, D. H., & McAllister, T. (2021). Extending Ultrasound Tongue Shape Complexity
Original languageEnglish
Number of pages2
Publication statusPublished - 4 Apr 2022
EventBAAP (British Association of Academic Phoneticians) Colloquium 2022 - York, online
Duration: 4 Apr 20228 Apr 2022


ConferenceBAAP (British Association of Academic Phoneticians) Colloquium 2022


  • tongue shapes
  • speech sound disorders
  • lingual gestures


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