Phonation threshold pressure and flow in excised human larynges

Mau, Ted; Muhlestein, Joseph; Callahan, Sean; Weinheimer, Kent T.; Chan, Roger W.

doi:10.1002/lary.21880

Cited by 23 publications

(22 citation statements)

References 22 publications

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“…This is consistent with PTP ranges reported by Mau et al 19 for their offset PTP. The ranges of Ps, flow rate, and fundamental frequencies are also included in the table.…”

Section: Discussionsupporting

confidence: 93%

Phonatory Characteristics of the Excised Human Larynx in Comparison to Other Species

2013

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Objective The purpose of this study was to (a) determine the conditions needed to elicit phonation from excised human larynges and the resultant range of phonations produced, (b) compare that with similar information previously obtained from canine, pig, sheep and cow and (c) relate those findings to previously reported information about viscoelastic properties of the vocal fold tissue (i.e. stress strain curves and Young’s Modulus). Methods Six human larynges of the geriatric group (age ranges 70–89) were mounted on the bench without supraglottic structures and phonation was achieved with the flow of heated and humidified air through the tracheal tube. Using various sutures to mimic the function of the laryngeal muscles, the larynges were put through a series of sustained oscillations with adduction as a control parameter. Results The human larynges oscillated with an average frequency that was close to the canine larynges, but the oscillation behavior and wide frequency range were similar to those of pig larynges. The similarity of the wide vibration frequency ranges of human and pig larynges may be due to the nonlinear behavior of their elasticity, which is related to their vocal folds high collagen content. On the contrary, other species with limited frequency ranges showed almost linear stress-strain curves due to the higher elastin and lower collagen contents. Conclusions The physiological differences in the linearity and ranges of oscillation of excised larynges reported in this study and previous studies are reflective of the tissue composition and mechanics.

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“…This is consistent with PTP ranges reported by Mau et al 19 for their offset PTP. The ranges of Ps, flow rate, and fundamental frequencies are also included in the table.…”

Section: Discussionsupporting

confidence: 93%

Phonatory Characteristics of the Excised Human Larynx in Comparison to Other Species

2013

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“…Four weeks after laser injury, the animals were sacrificed and their larynges harvested. Four of the eight larynges were subjected to excised larynx phonation, which was induced as previously described . Subglottal airflow was slowly increased until audible phonation occurred.…”

Section: Methodsmentioning

confidence: 99%

A rabbit vocal fold laser scarring model for testing lamina propria tissue‐engineering therapies

Mau

2014

The Laryngoscope

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Objectives/Hypothesis To develop a vocal fold scarring model using an ablative laser in the rabbit as a platform for testing bioengineered therapies for missing or damaged lamina propria. Study Design Prospective controlled animal study. Methods An optimal laser energy level was first determined by assessing the depths of vocal fold injury created by a Holmium:YAG laser at various energy levels on fresh cadaveric rabbit larynges. The selected energy level was then used to create controlled unilateral injuries in vocal folds of New Zealand white rabbits, with the contralateral folds serving as uninjured controls. After 4 weeks, the larynges were harvested and subjected to excised-larynx phonation with high-speed imaging and immunohistochemical staining for collagen types I and III, elastin, and hyaluronic acid (HA) with quantitative histological analysis. Results 1.8 joules produced full-thickness injury of the lamina propria without extensive muscle injury. After 4 weeks, the injured vocal folds vibrated with reduced amplitude (P = 0.036) in excised-larynx phonation compared to normal vocal folds. The injured vocal folds contained a higher relative density of collagen type I (P = 0.004), higher elastin (P = 0.022), and lower HA (P = 0.030) compared to normal controls. Collagen type III was unchanged. Conclusions With its potential for higher precision of injury, this laser vocal fold scarring model may serve as an alternative to scarring produced by cold instruments for studying the effects of vocal fold lamina propria bioengineered therapies. Level of Evidence N/A.

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“…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 Journal of the Acoustical Society of America

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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.

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Phonation threshold pressure and flow in excised human larynges

Cited by 23 publications

References 22 publications

Phonatory Characteristics of the Excised Human Larynx in Comparison to Other Species

Phonatory Characteristics of the Excised Human Larynx in Comparison to Other Species

A rabbit vocal fold laser scarring model for testing lamina propria tissue‐engineering therapies

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

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