An Exploratory Study of Voice Change Associated With Healthy Speakers After Transcutaneous Electrical Stimulation to Laryngeal Muscles

Objectives The purpose of this study was to determine if measurable changes in fundamental frequency (F0) and relative sound level (RSL) occurred in healthy speakers after transcutaneous electrical stimulation (TES) as applied via VitalStim (Chattanooga Group, Chattanooga, TN). Study Design A prospective, repeated-measures design. Methods Ten healthy female and 10 healthy male speakers, 20–53 years of age, participated in the study. All participants were nonsmokers and reported negative history for voice disorders. Participants received 1 hour of TES while engaged in eating, drinking, and conversation to simulate a typical dysphagia therapy protocol. Voice recordings were obtained before and immediately after TES. The voice samples consisted of a sustained vowel task and reading of the Rainbow Passage. Measurements of F0 and RSL were obtained using TF32 (Milenkovic, 2005, University of Wisconsin). The participants also reported any sensations 5 minutes and 24 hours after TES. Results Measurable changes in F0 and RSL were found for both tasks but were variable in direction and magnitude. These changes were not statistically significant. Subjective comments ranged from reports of a vocal warm-up feeling to delayed onset muscle soreness. Conclusions These findings demonstrate that application of TES produces measurable changes in F0 and RSL. However, the direction and magnitude of these changes are highly variable. Further research is needed to determine factors that may affect the extent to which TES contributes to significant changes in voice.