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

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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. Articulatory contacts, measured using electropalatography, were recorded simultaneously with P(io) to clarify how supraglottal constrictions affect P(io). Effects of consonant type on phonation thresholds could be explained mainly in terms of the magnitude and timing of vocal-fold abduction. Phonation offset occurred at lower values of P(io) before fricative-initial sequences than stop-initial sequences, and onset occurred at higher levels of P(io) following the unaspirated stops of clusters compared to fricatives, affricates, and aspirated stops. The vowel effects were somewhat surprising: High vowels had an inhibitory effect at voicing offset (phonation ceasing at lower values of P(io)) in short-duration consonant sequences, but a facilitating effect on phonation onset that was consistent across consonantal contexts. The vowel influences appear to reflect a combination of vocal-fold characteristics and vocal-tract impedance.

Section: Discussionmentioning

confidence: 92%

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

Koenig

Fuchs

Lucero

2011

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“…The symmetric case, with x r ¼ x ' , has been thoroughly analyzed in previous works under a variety of configurations (e.g., Lucero et al, 2011), and it has been found to provide a good characterization of experimental data from both human subjects (Lucero et al, 2012a) and mechanical replicas of the vocal folds (Lucero et al, 2012b).…”

Section: A Basic Equationsmentioning

confidence: 98%

“…Following previous work (Laje et al, 2001;Lucero et al, 2011), each vocal fold is represented by a lumped mass-damper-spring oscillator of the form…”

Section: A Basic Equationsmentioning

confidence: 99%

Self-entrainment of the right and left vocal fold oscillators

Lucero

Schoentgen

Haas

et al. 2015

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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. The results show that the subglottal threshold pressure for 1:1 entrainment increases with the asymmetry. Within that region, both folds oscillate with the same amplitude and with the lax fold delayed in time with regard to the tense fold. At large asymmetries, a region involving several different phase entrainments or toroidal regimes at constant threshold pressure appears. The effect of vocal fold collisions and asymmetry in the damping coefficients of the oscillators are explored next by means of numerical analyses. It is shown that the damping asymmetry expands the 1:1 entrainment region at low subglottal pressures across the whole asymmetry range. In the expanded region, the oscillator with the lowest natural frequency is dominant and the other oscillator has a large phase advance and small amplitude. The theoretical results are finally compared with data collected from a mechanical replica of the vocal folds.

“…Studies with physical models (Titze et al, 1995;Chan et al, 1997;Mau et al, 2011;Mendelsohn and Zhang, 2011), computer simulation models (Pickup and Thomson, 2011), and analytical calculations (Titze, 1988b;Lucero, 1998;Chan and Titze, 2006;Klemuk et al, 2010;Lucero et al, 2011;Fulcher et al, 2012) have shown that a near rectangular glottis (as viewed in the coronal plane) produces the lowest oscillation threshold pressure. (Direct measurement of this configuration in human subjects has not been reported.)…”

Section: A Criterion For Optimal Adductionmentioning

confidence: 99%

Bi-stable vocal fold adduction: A mechanism of modal-falsetto register shifts and mixed registration

Titze¹

2014

The origin of vocal registers has generally been attributed to differential activation of cricothyroid and thyroarytenoid muscles in the larynx. Register shifts, however, have also been shown to be affected by glottal pressures exerted on vocal fold surfaces, which can change with loudness, pitch, and vowel. Here it is shown computationally and with empirical data that intraglottal pressures can change abruptly when glottal adductory geometry is changed relatively smoothly from convergent to divergent. An intermediate shape between large convergence and large divergence, namely, a nearly rectangular glottal shape with almost parallel vocal fold surfaces, is associated with mixed registration. It can be less stable than either of the highly angular shapes unless transglottal pressure is reduced and upper stiffness of vocal fold tissues is balanced with lower stiffness. This intermediate state of adduction is desirable because it leads to a low phonation threshold pressure with moderate vocal fold collision. Achieving mixed registration consistently across wide ranges of F0, lung pressure, and vocal tract shapes appears to be a balancing act of coordinating laryngeal muscle activation with vocal tract pressures. Surprisingly, a large transglottal pressure is not facilitative in this process, exacerbating the bi-stable condition and the associated register contrast.