Electromyographic biofeedback training with patients exhibiting a hyperfunctional voice disorder.

Baseline EMG measures of general laryngeal area muscle tension while speaking and during silence were taken from a group of 21 normal subjects and 7 subjects diagnosed through indirect laryngoscopy as having vocal nodules. In an attempt to reduce their baseline scores, the vocal nodule patients underwent 8 EMG biofeedback training sessions followed by a 2-week follow-up session. Sophisticated listeners then judged the qualities of the voices produced during the base-line and follow-up sessions. Measures of sound pressure levels for the speech samples were also taken to determine their effects on EMG scores. Results of the statistical analyses revealed that significant differences in general laryngeal area muscle tension while speaking and in silence exist between normal and pathological subjects; and that subjects with vocal nodules could significantly reduce these tension levels with EMG biofeedback training. A positive correlation was then found between the EMG measures and the judgments of voice qualities. No correlations were found between EMG measures and sound pressure levels.