Abstract
Objectives
The purpose of this study was to measure changes in vocal fold closure associated with surface electrical stimulation (VitalStim®).
Methods
30 participants, 15 male and 15 female, ages 20–56 years, were included in the study. Participants underwent 1 hour of surface electrical stimulation, per guidelines reported in the VitalStim® manual. 3 trials of the vowel /ae/ were analyzed pre- and post-stimulation. Indirect estimates of glottal closure were obtained from the recorded vowels, as follows: 1) H1–H2: the amplitude of the first harmonic to the second harmonic (open quotient); 2) H1–A1: the ratio of the amplitude of the first harmonic to the amplitude of the first formant (glottal width); and 3) H1–A3: the ratio of the amplitude of the first harmonic to the amplitude of the third formant (spectral tilt).
Results
The direction and magnitude of change for all 3 parameters varied widely across participants. No significant difference occurred pre- vs. post-stimulation for any of the parameters.
Conclusions
VitalStim® did not systematically affect open quotient, glottal width, or spectral tilt. These results do not support the concept that VitalStim® has a direct effect upon vocal fold closure.
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