According to most previous studies, inducing movements in internal laryngeal muscles by
transcutaneous electrical stimulation (
TES) was impossible. However, the movements have been reported after using needle
electrodes inserted into the internal superior laryngeal nerve (ISLN). Herein, we aimed to apply an innovative
TES protocol to cause movements in vocal folds. A short duration and high frequency electrical current was applied by two surface
electrodes just above the entrance of ISLN to larynx. The subjects were 32 normal participants (mean age = 23.87; SD = 3.43). During
TES application, the vocal folds' movements were examined by flexible videonasolaryngoscopy. Statistical paired t test was used to analyze the differences of vocal folds opening angle, in degrees, during rest and
TES periods. Furthermore, the movements were judged by seven experienced speech pathologists via a 9-point rate scale from -1 (any abduction) to 8 (complete adduction). The mean vocal folds adduction increased by 35.68° (t = 9.35, p > 0.001) due to
TES application. The mean qualitative scores assigned by raters to each subject were between 6 and 7 points, which indicate an acceptable adduction in vocal folds through
TES. Unlike previous studies, the applied
TES protocol in this research induced significant vocal fold movements. This might be attributed to our different stimulation parameters, which were designed to penetrate deeply and stimulate ISLN specifically. It is worth noting that we introduced a novel
TES protocol, which should be confirmed and then examined as a complementary
therapy for
neurologic voice disorders in future studies.