Vocal tract steadiness: a measure of phonatory and upper airway motor control during phonation in dysarthria.

Acoustic analyses of upper airway and phonatory stability were conducted on samples of sustained phonation to evaluate the relation between laryngeal and articulomotor stability for 31 patients with dysarthria and 12 non-dysarthric control subjects. Significantly higher values were found for the variability in fundamental frequency and format frequency of patients who have Huntington's disease compared with normal subjects and patients with Parkinson's disease. No significant correlations were found between format frequency variability and the variability of the fundamental frequency for any subject group. These findings are discussed as they pertain to the relationship between phonatory and upper airway subsystems and the evaluation of vocal tract motor control impairments in dysarthria.