title: Effects of an Open Jaw Posture on Vowel Perception in the Aging Voice.
abstract: OBJECTIVE
  This study aimed to verify through an auditory-perceptual approach, whether an "open jaw" posture would result in improved speech quality for older adults.
  
  
  METHODS
  Forty normal-hearing listeners (20 males; 20 females) aged between 18 and 47 listened to vowel segments and performed two separate tasks: identifying vowels and comparing vowel clarity. Stimuli included vowels segmented from a sentence ("We saw two cars.") produced using a normal and an open jaw posture by 40 individuals aged between 30s and 80s. Three types of stimuli were presented: variable length and intensity, fixed length and variable intensity, and fixed length and normalized intensity. Mixed model analyses of variance were used to determine whether there was a jaw posture effect on the percentage of correct vowel identification. Chi-square tests were used to determine whether vowels produced with an open jaw posture were more likely to be identified as being "clearer."
  
  
  RESULTS
  Open jaw posture resulted in higher rates of correct vowel identification, and vowels from contrast pairs were consistently judged as being "clearer" than vowels produced in normal jaw posture. Investigations on the effect of stimulus type revealed that the jaw-related improvement in speech quality was not solely due to an increase in intensity or length induced by an open jaw posture.
  
  
  CONCLUSIONS
  Listeners assessing vowel identification and clarity in the aging voice were able to better differentiate among vowels spoken using an open jaw posture, and a greater number of vowels produced in an open jaw posture were perceived as sounding clearer.
authors.affiliation: Department of Communication Disorders, University of Canterbury, Christchurch, New Zealand.. Electronic address: h.mautner@xtra.co.nz.
authors.forename: Helene D
authors.initials: HD
authors.lastname: Mautner
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D001302:Audiometry, Speech; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D007568:Jaw / Q000033:anatomy & histology / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D010699:Phonation; D011187:Posture; D021641:Recognition, Psychology; D013061:Speech Acoustics; D013065:Speech Intelligibility; D013067:Speech Perception; D014833:Voice Quality; D055815:Young Adult
keywords: Aging voice; Geriatric voice; Intelligibility; Voice quality; Vowel perception