Relation of perceived breathiness to laryngeal kinematics and acoustic measures based on computational modeling.

Purpose: In this study, the authors sought to determine (a) how specific vocal fold structural and vibratory features relate to breathy voice quality and (b) the relation of perceived breathiness to 4 acoustic correlates of breathiness.

Method: A computational, kinematic model of the vocal fold medial surfaces was used to specify features of vocal fold structure and vibration in a manner consistent with breathy voice. Four model parameters were altered: vocal process separation, surface bulging, vibratory nodal point, and epilaryngeal constriction. Twelve naïve listeners rated breathiness of 364 samples relative to a reference. The degree of breathiness was then compared to (a) the underlying kinematic profile and (b) 4 acoustic measures: cepstral peak prominence (CPP), harmonics-to-noise ratio, and two measures of spectral slope.

Results: Vocal process separation alone accounted for 61.4% of the variance in perceptual rating. Adding nodal point ratio and bulging to the equation increased the explained variance to 88.7%. The acoustic measure CPP accounted for 86.7% of the variance in perceived breathiness, and explained variance increased to 92.6% with the addition of one spectral slope measure.

Conclusion: Breathiness ratings were best explained kinematically by the degree of vocal process separation and acoustically by CPP.