title: Changes in speech production associated with alphabet supplementation.
abstract: OBJECTIVE
  This study examined the effect of alphabet supplementation (AS) on temporal and spectral features of speech production in individuals with cerebral palsy and dysarthria.
  
  
  METHODS
  Twelve speakers with dysarthria contributed speech samples using habitual speech and while using AS. One hundred twenty listeners orthographically transcribed speech samples. Differences between habitual and AS speech were examined for intelligibility, rate, word duration, vowel duration, pause duration, pause frequency, vowel space, and first and second formant frequency (F1 and F2) values for corner vowels.
  
  
  RESULTS
  Descriptive results showed that intelligibility was higher, rate of speech was slower, and pause duration and pause frequency were greater for AS than for habitual speech. Inferential statistics showed that vowel duration, word duration, and vowel space increased significantly for AS. Vowel space did not differ for male and female speakers; however, there was an interaction between sex and speaking condition. Changes in vowel space were accomplished by reductions in F2 for /u/. Vowel space accounted for more variability in intelligibility than rate for AS; the opposite was true for habitual speech.
  
  
  CONCLUSIONS
  AS is associated with temporal and spectral changes in speech production. Spectral changes associated with corner vowels appear to be more important than temporal changes.
authors.affiliation: Department of Communicative Disorders and the Waisman Center, University of Wisconsin-Madison, 1500 Highland Avenue, Madison, WI 53705, USA. kchustad@wisc.edu
authors.forename: Katherine C
authors.initials: KC
authors.lastname: Hustad
authors.forename: Jimin
authors.initials: J
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D002547:Cerebral Palsy / Q000150:complications; D004401:Dysarthria / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D005260:Female; D006801:Humans; D008037:Linguistics / Q000379:methods*; D008297:Male; D010700:Phonetics; D013061:Speech Acoustics; D013068:Speech Production Measurement; D013070:Speech Therapy / Q000379:methods*; D014706:Verbal Learning