Vowel contrast and speech intelligibility in dysarthria

Heejin Kim, Mark Hasegawa-Johnson, Adrienne Perlman

Research output: Contribution to journalArticlepeer-review


Background/Aims: This study examined the spectral characteristics of American English vowels in dysarthria associated with cerebral palsy (CP), and investigated the relationship between a speaker's overall speech intelligibility and vowel contrast. Methods: The data were collected from 12 American English native speakers (9 speakers with a diagnosis of CP and 3 controls). Primary measures were F1 and F2 frequencies of 3 corner vowels /i, a, u/ and 3 noncorner vowels /I, 3, */. Six acoustic variables were derived from the formant measures, and were regressed against intelligibility: corner vowel space, noncorner vowel space, mean distance between vowels, F 1 and F2 variability, and overlap degree among vowels. Results: First, the effect of vowel was significant for both F1 and F2 measures for all speakers, but post hoc analysis revealed a reduced distinction at lower intelligibility. Second, regression functions relating intelligibility and acoustic variables were significant for overlap degree among vowels, F1 variability, corner vowel space and mean distance between vowels. Overlap degree among vowels accounted for the greatest amount of variance in intelligibility scores. Conclusion: A speaker's overall intelligibility in dysarthric speech is better represented by the overlap degree among vowels than by the vowel space.

Original languageEnglish (US)
Pages (from-to)187-194
Number of pages8
JournalFolia Phoniatrica et Logopaedica
Issue number4
StatePublished - Jun 2011


  • Dysarthria
  • Speech intelligibility
  • Vowel contrast

ASJC Scopus subject areas

  • Language and Linguistics
  • Linguistics and Language
  • Speech and Hearing
  • LPN and LVN


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