Clinical Research Directory

Transcranial Direct Current Stimulation on Singers Voice

Transcranial direct current stimulation (tDCS) can be used to temporarily and reversibly modulate brain functions and is an increasingly utilized tool to investigate the relationships between brain and behavior. This study aimed to identify the effects of tDCS on vocal quality, vocal range, neuromotor functioning of the larynx and self-reported vocal effort in vocally healthy singers. This is a triple-blinded, sham-controlled, randomized clinical trial. The participants were randomized to one of the three tDCS groups (primary motor cortex, cerebellum or sham). In each group a voice training was applied at the same tDCS time. The three groups are: (i) cerebellum; (ii) primary motor cortex (M1); (iii) sham. The tDCS parameters in the active groups are anodal - 2mA for 20 minutes, at the sham group the stimuli are finished 30 secondes before starting. Volunteers passed for 10 intervention days and they were evaluated for vocal performance before the sessions, in the day 5 of intervention, the last day of intervention (day 10) and 1 month later for follow up evaluation. Voice recordings was taken to assess the following vocal parameters: vocal range profile (VRP) at weak and strong intensities; vocal quality (jitter, shimmer, irregularity, glottal-to-noise excitation ratio, CPPS,HNR, and dysphonia acoustic index) at weak, habitual, and strong intensities; laryngeal diadochokinesis, and self-reported vocal effort using the adapted Borg CR10 scale.