Perceptual and Quantitative Assessment of Dysphonia Across Vowel Categories

This study aims to determine the sensitivity of perceptual and computational correlates of breathy and rough voice quality (VQ) across multiple vowel categories using single-variable matching tasks (SVMTs).

Sustained phonations of /a/, /i/, and /u/ from 20 dysphonic talkers (10 with primarily breathy voices and 10 with primarily rough voices) were selected from the University of Florida Dysphonic Voice Database. For primarily breathy voices, perceived breathiness was judged, and for primarily rough voices, perceived roughness was judged by the same group of 10 listeners using an SVMT with five replicates per condition. Measures of pitch strength, cepstral peak, and autocorrelation peak were applied to models of the perceptual data.

Intra- and inter-rater reliability were high for both the breathiness and the roughness perceptual tasks. For breathiness judgments, the effect of vowel was small. Averaged over all talkers and listeners, breathiness judgments for /a/, /i/, and /u/ were -11.6, -11.2, and -12.2 dB noise-to-signal ratio, respectively. For roughness judgments, the effect of vowel was larger. The perceived roughness of /a/ was higher than /i/ or /u/ by 3 dB modulation depth. Pitch strength was the most accurate predictor of breathiness matching (r² = 0.84-0.94 across vowels), and log-transformed autocorrelation peak was the most accurate predictor of roughness matching (r² = 0.59-0.83 across vowels).

Breathiness is more consistently represented across vowels for dysphonic voices than roughness. This work represents a critical step in advancing studies of voice quality perception from single vowels to running speech.