title: Effects of Hawley retainers on consonants and formant frequencies of vowels.
abstract: OBJECTIVE
  To assess (1) whether Hawley retainers cause speech disturbance and (2) the duration of speech adaptation to Hawley retainers with objective and subjective tests.
  
  
  METHODS
  Twelve adolescents, aged 11.11 to 18.03 years, were included in this study. The assessment of speech sounds were done subjectively using an articulation test and objectively using acoustic analysis before and after Hawley retainer application.
  
  
  RESULTS
  After wearing Hawley retainers, patients showed statistically significant speech disturbances on consonants [ş] and [z]. Regarding the vowels, statistically significant changes were recorded with [i], while F1 increased and F2 and F3 decreased.
  
  
  CONCLUSIONS
  The tongue changes its target position with the application of a foreign body within the mouth; however, in time it adapts to that new situation.
authors.affiliation: Department of Audiology and Speech Pathology, Hacettepe University Faculty of Medicine, Ankara, Turkey. mavis@hacettepe.edu.tr
authors.forename: Mavis Emel
authors.initials: ME
authors.lastname: Kulak Kayikci
authors.forename: Seden
authors.initials: S
authors.lastname: Akan
authors.forename: Semra
authors.initials: S
authors.lastname: Ciger
authors.forename: Soner
authors.initials: S
authors.lastname: Ozkan
mesh_terms: D000222:Adaptation, Physiological; D000293:Adolescent; D001184:Articulation Disorders / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D018704:Orthodontic Retainers / Q000009:adverse effects*; D013062:Speech Articulation Tests