title: Developmental trajectory for production of prosody: lexical stress contrastivity in children ages 3 to 7 years and in adults.
abstract: OBJECTIVE
  Accurate production of lexical stress within English polysyllabic words is critical for intelligibility and is affected in many speech-language disorders. However, models of speech production remain underspecified with regard to lexical stress. In this study, the authors report a large-scale acoustic investigation of lexical stress production in typically developing Australian English-speaking children ages 3-7 years (  n = 73) compared with young adults (  n = 24).
  
  
  METHODS
  Participants named pictures of highly familiar strong-weak and weak-strong polysyllabic words. Of 388 productions, 325 met criteria for acoustic measurement. Relative vowel duration, peak intensity, and peak   f  (0) over the first two syllables were measured.  Result Lexical stress was marked consistently by duration and intensity but not   f  (0). Lexical stress on strong-weak words was adultlike by 3 years. All 3 measures showed significant differences between adults and children for weak-strong words still present at 7 years.
  
  
  CONCLUSIONS
  Our findings suggest that protracted development of weak-strong stress production reflects physiological constraints on producing short articulatory durations and rising intensity contours. Findings validate treatment that is centered on strong-weak stress production for children ≥ 3 years with dysprosody. Although intervention for the production of weak-strong words may be initiated before age 7 years, reference to normative acoustic data is preferable to relying on perceptual judgments of accuracy.
authors.affiliation: University of Sydney, New South Wales, Australia. kirrie.ballard@sydney.edu.au
authors.forename: Kirrie J
authors.initials: KJ
authors.lastname: Ballard
authors.forename: Danica
authors.initials: D
authors.lastname: Djaja
authors.forename: Joanne
authors.initials: J
authors.lastname: Arciuli
authors.forename: Deborah G H
authors.initials: DG
authors.lastname: James
authors.forename: Jan
authors.initials: J
authors.lastname: van Doorn
mesh_terms: D000328:Adult; D002648:Child; D002657:Child Development; D002663:Child Language; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D008954:Models, Biological; D010699:Phonation; D010700:Phonetics; D013060:Speech; D013061:Speech Acoustics; D013068:Speech Production Measurement; D055815:Young Adult