Relation of Perceived Breathiness to Laryngeal Kinematics and Acoustic Measures Based on Computational Modeling

Abstract

Purpose To determine 1) how specific vocal fold structural and vibratory features relate to breathy voice quality and 2) the relation of perceived breathiness to four 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 1) the underlying kinematic profile and 2) four 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. Conclusions Breathiness ratings were best explained kinematically by the degree of vocal process separation and acoustically by CPP.

Acoustic and Perceptual Effects of Left–Right Laryngeal Asymmetries Based on Computational Modeling

“…The acoustic and perceptual outcomes of fine gradations of symmetric vocal fold structural and vibratory differences have been studied using a computational kinematic model (Samlan & Story, 2011; Samlan, Story, & Bunton, 2013), and the model was adapted for the current study to allow specification of asymmetric characteristics of the vocal folds. The kinematic model was ideal for the current study because it allows specification of individual structural and movement properties without assuming the underlying biomechanical properties and neuromuscular controls.…”

Performance of Phonatory Deviation Diagrams in Synthesized Voice Analysis

“…These findings emphasize that the degree of separation between vocal processes, the convexity of the free edge of the vocal folds and the time of the closed phase of the glottal cycle mainly account for the presence of auditorily perceived breathiness [54]. In turn, deviations in the aforementioned physiological parameters are also a source of irregularity in vocal fold vibrations, which would explain the presence of predominantly breathy voice signals in the lower right quadrant.…”

“…This finding may be explained by the fact that signals located in the upper left quadrant would most likely have exclusively additive noise (breathiness), without vibration irregularities (roughness). In general, the presence of a higher degree of additive noise is compatible with a longer vocal fold shift toward the midline [54]. In turn, the presence of this longer shift is also a source of vibration irregularities, thereby complicating the isolation of the breathiness parameter in signals with more severe deviations.…”

“…However, in a qualitative analysis, we observed a progressive increase in the proportion of circularly shaped signals as a function of increased severity of voice disorder. This fact may explain why the presence of a glottal slit may be a source of both additive noise and vibration irregularities of the vocal folds [54], which explains the signal shift in both the vertical and horizontal axes overlapping with all other conditions that generate irregularities in glottal cycles.…”

Perceptual consequences of changes in epilaryngeal area and shape

“…A kinematic vocal tract model (Story, 2005;Samlan et al, 2013) was used to create five epilaryngeal cavity shapes by orthogonally modifying epilaryngeal area ("constricted" vs "expanded") and location of the constriction/expansion within the epilarynx (approximate locations of the ventricular folds and aryepiglottic folds), relative to a fifth "neutral" condition based on a naturally produced vowel. The ventricular folds were modeled as a 0.4 cm section beginning just superior to the vocal folds, 1 and the aryepiglottic folds were similarly modeled as a 0.4 cm section at a location 2.0 cm superior to the vocal folds.…”