Effect of Transcranial Direct Current Stimulation on the Voice

Recently, non-invasive brain stimulation (NIBS) techniques , including transcranial direct current stimulation (tDCS), have been employed to enhance vocal skills. tDCS can be used to temporarily and reversibly modulate brain functions and is an increasingly popular tool for investigating the relationships between the brain and behavior . The aim of the present study is investigate the effect of tDCS applied to different areas on the voice of vocally healthy non-singers. This is a randomized crossover clinical trial, approved by the Research Ethics Committee of the Federal University of Pernambuco, number 5,758,856. Vocally healthy people from the city of Recife and its Metropolitan Region, aged between 18 and 45 years, participated in the study.Each participant underwent four tDCS stimulations in different areas with a 7-day washout period between stimulations to study their vocal assessments before and after tDCS. The targeted places were the primary motor cortex (M1), primary somatosensory cortex (S1), Cerebellum, and dorsolateral prefrontal cortex (DLPFC). All participants were subjected to voice acessments analysis immediately before and after tDCS application in each area. Data normality will be analyzed using the Shapiro-Wilk test, rejecting the hypothesis of normal distribution when p\<0.05. ANOVA will be applied to design repeated measures in case of normality and in the existence of asymmetric data, Friedmann's ANOVA will be used for repeated measures. For the comparison of values before and after application of the technique and between modes of execution of the technique (with and without non-invasive neuromodulation), tests will be applied for related and independent samples, respectively, with a significance level of 5%