The Relationship Between the Aerodynamic Parameters of Voice and Perceptual Evaluation in the Iranian Population With or Without Voice Disorders

Objectives. Aerodynamic evaluations can provide useful information about the interaction between the respiratory and the phonation systems. The present study was conducted to investigate the relationship of maximum phonation time (MPT), vital capacity (VC), and phonation quotient (PQ) with perceptual evaluation in different types of dysphonia. The relationship between these parameters and the type of dysphonia was also examined. Materials and Methods. The study participants consisted of 300 individuals with different types of dysphonia (104 women and 196 men) and 100 healthy samples (63 women and 37 men). A professional speech-language pathologist conducted the perceptual evaluation based on the G (grade) component of the GRBAS scale, which stands for grade, roughness, breathiness, asthenia, and strain. VC was measured using a spirometer and MPT using a stopwatch. PQ was calculated as the ratio of VC to MPT. Results. The difference between the mean +/- standard deviation of PQ, VC, and MPT were found to be significant at all the four degrees of dysphonia severity (P < 0.001). There was a significant difference in mean MPT and VC between the genders (P < 0.001), but no significant gender differences were observed in terms of the mean PQ (P = 0.346). The study participants were classified into four groups, including the organic dysphonia group, neurologic dysphonia and functional dysphonia groups, and the normal group; the study variables measured were found to be significantly different between all the four groups (P < 0.001). Conclusion. As MPT and PQ were correlated with the perceptual G (grade) and differentiated dysphonic from healthy individuals, clinicians are recommended to take account of them in their instrumental evaluations.