title: The relationship of vocal tract dimensions and substitution of the palatal approximant /j/ for the alveolar trill /r/.
abstract: OBJECTIVE
  To investigate the relationship of the vocal tract dimensions and dental arches in participants with substitution of palatal approximant /j/ for the trill variant of /r/.
  
  
  METHODS
  Cephalograms and dental casts of 60 native speakers of Arabic were used for comparison. The experimental group included 30 participants with substitution of /j/ for the trill variant of /r/ (17 males and 13 females, age ranged between 15-20 years, M = 18.7 years, SD = 1.27). The control group included 30 normal speakers (15 males and 15 females, age ranged between 15-20 years, M = 18.3 years, SD = 1.67). Both groups had class I occlusion.
  
  
  RESULTS
  The experimental group showed significantly shorter maxillary length, p < 0.05, and narrower vocal tract dimensions compared to the control group, p < 0.05. Tongue length (TGL) and height (TGH) and soft palate length (PNSP) and thickness (MPT) were statistically significantly reduced in the experimental group compared to the control group, p < 0.05. The distance between the hyoid bone and retrognathion or C3 was significantly shorter in the experimental group compared to the control group, p < 0.05. Inter-canine widths and dental arch lengths were significantly shorter in the experimental group compared to the control group, p < 0.05.
  
  
  CONCLUSIONS
  The substitution of /j/ for the trill variant of /r/ is associated with altered dimensions of the vocal tract. These alterations may explain the residual articulation disorder during the production of the trilled /r/ compared to other sound classes that respond to speech therapy. Orthodontic and Maxillo facial surgery consultation might be needed when providing therapy to individuals with this particular articulation disorder.
authors: Jordan University of Science & Technology , Irbid , Jordan.
authors: Firas
authors: F
authors: Alfwaress
authors: Emad Al
authors: EA
authors: Maaitah
authors: Suzan
authors: S
authors: Al-Khateeb
authors: Zakaria Abu
authors: ZA
authors: Zama
mesh_terms: D000293:Adolescent; D002508:Cephalometry; D005260:Female; D006801:Humans; D007830:Larynx / Q000033:anatomy & histology*; D008297:Male; D009055:Mouth / Q000033:anatomy & histology*; D009296:Nasal Cavity / Q000033:anatomy & histology*; D010614:Pharynx / Q000033:anatomy & histology*; D013060:Speech / Q000502:physiology*; D055815:Young Adult
keywords: Vocal tract dimensions; alveolar trill; articulation disorders