Numerical solution of Rothenberg's equation of the glottal airflow rate as a function of the glottal area using backward differentiation (L).

This letter shows the application of backward differentiation formulas to solve a differential equation by Rothenberg [(1981). Department for Speech, Music and Hearing Quarterly Progress and Status Report (KTH Royal Institute of Technology, Stockholm, Sweden), Vol. 22], which models the glottal airflow rate vs the glottal area.

Parametrization of the vocal tract area function using a subset selection approach (L).

This letter introduces a parametrization of the vocal tract area function based on the position of a few points along the vocal tract. A QR decomposition algorithm is applied to area function data in various vowel configurations in order to identify those points with the most independent position patterns across vowels. Each point defines the shape of an associated kinematic region, and the overall area function is determined by the combination of the kinematic regions' shapes.

The Performance of the Acoustic Voice Quality Index and Acoustic Breathiness Index in Synthesized Voices.

Objective: The aim of the present study was to investigate the performance of the Acoustic Voice Quality Index (AVQI) and the Acoustic Breathiness Index (ABI) in synthesized voice samples.

Method: The validity of the AVQI and ABI performances was analyzed in synthesized voice samples controlling the degree of predefined deviations for overall voice quality (G-scale) and breathiness (B-scale). A range of 26 synthesized voice samples with various severity degrees in G-scale with and without prominence of breathiness for male and female voices were created.

Smoothness of an equation for the glottal flow rate versus the glottal area.

This letter proposes a correction to an equation by Titze [J. Acoust. Soc.

Self-entrainment of the right and left vocal fold oscillators.

This article presents an analysis of entrained oscillations of the right and left vocal folds in the presence of asymmetries. A simple one-mass model is proposed for each vocal fold. A stiffness asymmetry and open glottis oscillations are considered first, and regions of oscillation are determined by a stability analysis and an averaging technique.

Testing the reliability of Grade, Roughness and Breathiness scores by means of synthetic speech stimuli.

This article describes a synthesizer of disordered voices and reports a test of the reliability of Grade, Roughness, and Breathiness scores assigned to synthetic stimuli by eight expert listeners in two sessions. Speech stimuli [a], [i], [u], [ai], and [ia] were synthesized with three values of vocal frequency and four levels of vocal jitter and pulsatile additive noise each. The agreement and correlation of scores assigned by the same rater in different sessions, or by different raters in the same session, accord with published data.

Effect of source-tract acoustical coupling on the oscillation onset of the vocal folds.

This paper analyzes the interaction between the vocal folds and vocal tract at phonation onset due to the acoustical coupling between both systems. Data collected from a mechanical replica of the vocal folds show that changes in vocal tract length induce fluctuations in the oscillation threshold values of both subglottal pressure and frequency. Frequency jumps and maxima of the threshold pressure occur when the oscillation frequency is slightly above a vocal tract resonance.

Effects of consonant manner and vowel height on intraoral pressure and articulatory contact at voicing offset and onset for voiceless obstruents.

In obstruent consonants, a major constriction in the upper vocal tract yields an increase in intraoral pressure (P(io)). Phonation requires that subglottal pressure (P(sub)) exceed P(io) by a threshold value, so as the transglottal pressure reaches the threshold, phonation will cease. This work investigates how P(io) levels at phonation offset and onset vary before and after different German voiceless obstruents (stop, fricative, affricates, clusters), and with following high vs low vowels.

A lumped mucosal wave model of the vocal folds revisited: recent extensions and oscillation hysteresis.

This paper examines an updated version of a lumped mucosal wave model of the vocal fold oscillation during phonation. Threshold values of the subglottal pressure and the mean (DC) glottal airflow for the oscillation onset are determined. Depending on the nonlinear characteristics of the model, an oscillation hysteresis phenomenon may occur, with different values for the oscillation onset and offset threshold.

Validation of theoretical models of phonation threshold pressure with data from a vocal fold mechanical replica.

This paper analyzes the capability of a mucosal wave model of the vocal fold to predict values of phonation threshold lung pressure. Equations derived from the model are fitted to pressure data collected from a mechanical replica of the vocal folds. The results show that a recent extension of the model to include an arbitrary delay of the mucosal wave in its travel along the glottal channel provides a better approximation to the data than the original version of the model, which assumed a small delay.

Analysis of facial motion patterns during speech using a matrix factorization algorithm.

This paper presents an analysis of facial motion during speech to identify linearly independent kinematic regions. The data consists of three-dimensional displacement records of a set of markers located on a subject's face while producing speech. A QR factorization with column pivoting algorithm selects a subset of markers with independent motion patterns.

Speech production variability in fricatives of children and adults: results of functional data analysis.

This study investigates token-to-token variability in fricative production of 5 year olds, 10 year olds, and adults. Previous studies have reported higher intrasubject variability in children than adults, in speech as well as nonspeech tasks, but authors have disagreed on the causes and implications of this finding. The current work assessed the characteristics of age-related variability across articulators (larynx and tongue) as well as in temporal versus spatial domains.

Stop-consonant voicing and intraoral pressure contours in women and children.

Previous authors have established that stop consonant voicing is more limited in young children than adults, and have ascribed this to immature vocal-tract pressure management. Physical development relevant to speech aerodynamics continues into adolescence, suggesting that consonant voicing development may also persist into the school-age years. This study explored the relationship between stop consonant voicing and intraoral pressure contours in women, 5 year olds, and 10 year olds.

Laryngeal and aerodynamic adjustments for voicing versus devoicing of /h/: a within-speaker study.

The aim of this within-speaker case study was to explore how effectively a phonetically trained speaker could alter the likelihood of voicing around abduction, and what changes he made to do so. An American English-speaking male produced intervocalic /h/ in varying loudness and vowel contexts. When given no specific instructions about voicing (block 1), he produced almost entirely voiced /h/.

On the relation between the phonation threshold lung pressure and the oscillation frequency of the vocal folds.

This Letter presents an extension of a previous equation for the phonation threshold pressure by Titze [I. R. Titze, J.

Phonation thresholds as a function of laryngeal size in a two-mass model of the vocal folds.

This letter analyzes the oscillation onset-offset conditions of the vocal folds as a function of laryngeal size. A version of the two-mass model of the vocal folds is used, coupled to a two-tube approximation of the vocal tract in configuration for the vowel /a/. The standard male configurations of the laryngeal and vocal tract models are used as reference, and their dimensions are scaled using a single factor.

Multidimensional analyses of voicing offsets and onsets in female speakers.

This study investigates cross-speaker differences in the factors that predict voicing thresholds during abduction-adduction gestures in six normal women. Measures of baseline airflow, pulse amplitude, subglottal pressure, and fundamental frequency were made at voicing offset and onset during intervocalic /h/, produced in varying vowel environments and at different loudness levels, and subjected to relational analyses to determine which factors were most strongly related to the timing of voicing cessation or initiation. The data indicate that (a) all speakers showed differences between voicing offsets and onsets, but the degree of this effect varied across speakers; (b) loudness and vowel environment have speaker-specific effects on the likelihood of devoicing during /h/; and (c) baseline flow measures significantly predicted times of voicing offset and onset in all participants, but other variables contributing to voice timing differed across speakers.

Empirical modeling of human face kinematics during speech using motion clustering.

In this paper we present an algorithm for building an empirical model of facial biomechanics from a set of displacement records of markers located on the face of a subject producing speech. Markers are grouped into clusters, which have a unique primary marker and a number of secondary markers with an associated weight. Motion of the secondary markers is computed as the weighted sum of the primary markers of the clusters to which they belong.

Comparison of measures of variability of speech movement trajectories using synthetic records.

In speech research, it is often desirable to assess quantitatively the variability of a set of speech movement trajectories. This problem is studied here using synthetic trajectories, which consist of a common pattern and terms representing amplitude and phase variability. The results show that a technique for temporal alignment of the records based on functional data analysis allows us to extract the pattern and variability terms as separate functions, with good approximation.

Simulations of temporal patterns of oral airflow in men and women using a two-mass model of the vocal folds under dynamic control.

In this study we use a low-dimensional laryngeal model to reproduce temporal variations in oral airflow produced by speakers in the vicinity of an abduction gesture. It attempts to characterize these temporal patterns in terms of biomechanical parameters such as glottal area, vocal fold stiffness, subglottal pressure, and gender differences in laryngeal dimensions. A two-mass model of the vocal folds coupled to a two-tube approximation of the vocal tract is fitted to oral airflow records measured in men and women during the production of /aha/ utterances, using the subglottal pressure, glottal width, and Q factor as control parameters.

Identifying a differential equation for lip motion.

A second order homogeneous differential equation is fitted to lip trajectories during speech at fast, normal, and slow speaking rates. The objective is to characterize lip motion in terms of biomechanical parameters such as stiffness, damping, and applied external forces. The results show that, at fast speaking rates, the lip behaves like a simple mass-spring oscillator moving at its natural frequency, and with low variability across repetitions.