The aim of this prospective study is to assess the vocal changes in patients using nasal continuous positive airway pressure (CPAP). A total of 18 subjects using nasal CPAP were assessed by grading their voice perceptually as G0 for normal voice and G3 for severe hoarseness. Acoustic analysis was also performed and the following parameters were measured: fundamental frequency, habitual pitch, shimmer, relative average perturbation, voice turbulence index, and noise-to-harmonic ratio. The same was done for a control group matched according to age and gender. There was a statistically significant difference in the perceptual evaluation between the CPAP group and controls, with more patients in the former group having moderate hoarseness. There was also an increase in the perturbation parameters and a decrease in the fundamental frequency and habitual pitch in the CPAP group compared to controls. The increase in shimmer was statistically significant. The usage of nasal CPAP seems to induce vocal changes that are perceived as mild to moderate hoarseness, together with an increase in the perturbation parameters. These seem to be secondary to the upper airway dryness reported in these patients. The hypothetical effect of nasal CPAP on the sol layer of the vocal folds is discussed.