Voice disorders affect voice production (phonation) in aspects such as volume, quality, pitch, resonance, flexibility, and endurance. These vocal changes are expressions of disorders of the larynx, resonator, and vocal tract function, as well as breathing and respiratory mechanics, which can be attributed to heterogeneous local causes. Additionally, there are miscoordination of various parts of the vocal tract and systemic diseases such as hypothyroidism or hyperthyroidism, imbalance of sex hormones, or growth hormone disorders (Verdolini et al. 2006).