Auditory-perceptual Evaluation of Normal and Dysphonic Voices Using the Voice Deviation Scale

Abstract

This study aims to (1) determine the cutoff values of the overall severity (OS) of vocal deviation on the visual analog scale (VAS) based on the ratings of the numerical scale (NS); and (2) verify the power of discrimination of these cutoff values according to different degrees of vocal deviation. This is a prospective study. The auditory-perceptual evaluation was performed by four speech-language pathologists who used two protocols with different scalar properties: the VAS and the 4-point NS. Vocal samples from142 women and 69 men, plus 10% of repetition, with and without vocal complaints, ranging from 19 to 60 years were included. The analyzed speaking task was the counting from 1 to 10. For both protocols, the judges rated the OS. Based on the correspondence between the two scales, the cutoff values of the OS on the VAS obtained were 35.5, 50.5, and 90.5 points. The 35.5 value corresponds to the cutoff point between normal variability and mild/moderate vocal deviations; the 50.5 value corresponds to the cutoff point between mild/moderate and moderate vocal deviations; the 90.5 value corresponds to the cutoff point between moderate and severe deviations. Areas under the receiver operating characteristic curve for the three cutoff values were 0.918, 0.948, and 0.970, respectively. The cutoff values of the OS on the VAS were obtained, and the areas under the ROC curve showed that all the three cutoff points had excellent accuracy that represents a higher power of discrimination of different degrees of vocal deviations.