Long-term phonatory instability in individuals with multiple sclerosis

Lena Hartelius, Eugene H. Buder, Edythe A. Strand

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


This paper uses a new approach to describe and quantify the long-term phonatory instability of speakers with MS. Sustained vowel phonations of 20 individuals with a definite diagnosis of multiple sclerosis (MS) and 20 age- and gender-matched individuals with normal speech were recorded. The phonations were f0 and intensity analyzed and subjected to spectral analysis using the Fast Fourier Transform. Three methods for analyzing the instabilities are presented, compared, and related to perceptual judgments: (a) coefficients of variation, (b) magnitude-based analysis of spectral energy, and (c) frequency-based analysis of spectral components. All measures reliably distinguished between individuals with MS and persons with normal speech. A single factor based on a linear discriminant analysis of the frequency-based measures was especially useful in distinguishing these groups. Critical frequency bands of instability, corresponding to wow (1-2 Hz), tremor (around 8 Hz), and flutter (17-18 Hz), distinguished the MS group from those of the control group.

Original languageEnglish (US)
Pages (from-to)1056-1072
Number of pages17
JournalJournal of Speech, Language, and Hearing Research
Issue number5
StatePublished - Oct 1997


  • Acoustic analysis
  • Multiple sclerosis
  • Phonation
  • Phonatory instability
  • Vocal tremor

ASJC Scopus subject areas

  • Language and Linguistics
  • Linguistics and Language
  • Speech and Hearing


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