EMG biofeedback as a function of voice-quality change.

Changes in electromyography (EMG) accompanying changes in voice quality are reported. Audio recordings were obtained from four normal speakers during production of sustained vowels, counting and reading. These were uttered first in a normal voice and then in a voluntarily produced harsh voice. Perceptual ratings of voice quality of these utterances were made and compared to averaged EMG values obtained during the productions. The surface electrode placement remained unchanged over each of the cricothyroid areas for both normal and harsh voice. For one of the speakers, changes in EMG paralleled changes in vocal quality. For the other three, changes in EMG were variable, and sometimes minimal, in comparison to changes in voice. The results are discussed in relation to the clinical use of EMG for voice disorders.