Prediction of vocal roughness using measures of temporal envelope fluctuation obtained from an auditory model

Vocal roughness often is present in many voice disorders, but the assessment of roughness mainly depends on the subjective auditory-perceptual evaluation and lacks unique acoustic correlates. This study aimed to apply the concept of roughness in general sound quality perception to vocal roughness assessment and to characterize the relationship between vocal roughness and temporal envelope fluctuation measures obtained from a biologically inspired auditory processing model. Ten /ɑ/ recordings with a wide range of roughness were selected from an existing database. Ten listeners evaluated perceived roughness using a single-variable matching task. Temporal envelope fluctuations of the recordings were analyzed with an auditory processing model of amplitude modulation based on a modulation filterbank tuned to different modulation frequencies. Pitch strength and the smoothed cepstral peak prominence (CPPS) also were computed for comparison. Individual simple regression models yielded envelope standard deviation from a modulation filter with a low center frequency (64.3 Hz) as a statistically significant predictor of vocal roughness with a strong coefficient of determination (R2 = 0.81). Pitch strength and CPPS were not significant predictors of roughness. These results support the utility of envelope fluctuation measures from an auditory model as objective correlates of vocal roughness. [Work supported by NIH R01DC009029.]