Relation of Structural and Vibratory Kinematics of the Vocal Folds to Two Acoustic Measures of Breathy Voice Based on Computational Modeling

Abstract

Purpose To relate vocal fold structure and kinematics to two acoustic measures: cepstral peak prominence (CPP) and the amplitude of the first harmonic relative to the second (H1-H2). Method A computational, kinematic model of the medial surfaces of the vocal folds was used to specify features of vocal fold structure and vibration in a manner consistent with breathy voice. Four model parameters were altered: degree of vocal fold adduction, surface bulging, vibratory nodal point, and supraglottal constriction. CPP and H1-H2 were measured from simulated glottal area, glottal flow and acoustic waveforms and related to the underlying vocal fold kinematics. Results CPP decreased with increased separation of the vocal processes, whereas the nodal point location had little effect. H1-H2 increased as a function of separation of the vocal processes in the range of 1–1.5 mm and decreased with separation > 1.5 mm. Conclusions CPP is generally a function of vocal process separation. H1*-H2* will increase or decrease with vocal process separation based on vocal fold shape, pivot point for the rotational mode, and supraglottal vocal tract shape, limiting its utility as an indicator of breathy voice. Future work will relate the perception of breathiness to vocal fold kinematics and acoustic measures.

Development of a glottal area index that integrates glottal gap size and open quotient

“…Despite this two-part physical process, AC/OQ is linearly related to continuous changes in quality and to the acoustic measure CPP, linking these three domains in a straightforward manner. These findings are consistent with results of Samlan and Story (2011), whose computer simulation showed that increasing the separation between the vocal processes at maximum closure (controlled by a vocal fold adduction parameter) generally led to decreased harmonic energy and increased random (noise) energy, which resulted in decreased CPP. The twoway physical process (captured by AC/OQ) and CPP values observed in this study lend experimental support to the simulated relationship between kinematic (anatomical) parameters and acoustics measures in Samlan and Story (2011).…”

“…In Chen et al (2011), glottal gap size was shown to affect the cepstral peak prominence (CPP; Hillenbrand et al, 1994) and the harmonics-to-noise ratio (de Krom, 1993), indicating the presence of relatively more spectral noise with increasing glottal gap size. Simulation using a computational, kinematic model of the vocal folds showed that the acoustic measure CPP decreased with increased separation of the vocal processes, which was partially manifested as the size of the glottal gap during the maximum glottal closure (Samlan and Story, 2011).…”

Regulation of glottal closure and airflow in a three-dimensional phonation model: Implications for vocal intensity control

“…Noise production due to turbulent flow developed downstream of the glottis was modeled by adding an additional component u j,noise to the instantaneous jet velocity, similar to previous studies (e.g., Samlan and Story, 2011) …”

Joint Source-Filter Optimization for Accurate Vocal Tract Estimation Using Differential Evolution

“…The voice source component of the model consists of a kinematic representation of the medial surfaces of the vocal folds ( [45], [46]; and specifically [47]) for which surface bulging, adduction, length, and thickness are control parameters, as well as fundamental frequency. Vocal fold length and thickness are set to be 1.6 cm and 0.3 cm, respectively.…”

“…Acoustic wave propagation in the subglottal and supraglottal airspaces was computed with a wave-reflection model [50], [51] that included energy losses due to yielding walls, viscosity, heat conduction, and radiation at the lips [50]. This form of the computational model was similarly used to generate synthetic speech samples for [47]; a more extensive description of the model can be found there.…”