Transcranial Direct Current Stimulation Combined With Straw Phonation in Water Technique in Subjects With and Without Vocal Symptoms: Exploratory Study.

Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulation technique whose effects on the voice have been explored, although still in a preliminary manner. The aim of this exploratory study was to verify the immediate effect of tDCS combined with straw phonation in water technique on the voice of adults with and without vocal symptoms. Twenty-two volunteers (11 with vocal symptoms and 11 without vocal symptoms) were evaluated before and after the exercise with straw phonation in water and tDCS session in primary motor cortex (M1). All participants underwent one anodal tDCS session (20 minutes; 2 mA) and one sham tDCS session with a 1-week washout period. The order of the real stimulus session and sham session was defined by drawing lots for blinding purposes. Voice recorders were taken to assess the acoustic parameters of vocal quality (jitter, shimmer, and glottal-to-noise excitation ratio), cepstral measures, acoustic index of dysphonia, voice range profile, laryngeal diadochokinesis, and in vocal effort self-perceived. RESULTS: There was a more pronounced decrease in vocal effort after neuromodulation and an improvement in dysphonia acoustic index and spectral decline, in habitual and high-intensity in subjects with and without vocal symptoms, indicating probable improvement in vocal signal regularity. There was an improvement in CPPS in both groups and a decrease in vocal effort self-perceived, both in the situation with neuromodulation and in the sham stimulus. There was also an increase in maximum intensity values in the groups with real and sham stimulation. CONCLUSION: Neuromodulation combined with the technique with straw phonation in water potentiated the decrease in self-perceived vocal effort in subjects with and without vocal symptoms and an improvement in cepstral values in subjects with vocal symptoms. A possible improvement in spectral decline values was also observed in subjects with vocal symptoms.