Pressure distributions in a static physical model of the uniform glottis: Entrance and exit coefficients

Fulcher, Lewis P.; Scherer, Ronald C.; Powell, T.

doi:10.1121/1.3514424

Cited by 21 publications

(35 citation statements)

References 10 publications

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“…8. However, the large glottal width behavior of the entrance loss coefficients reported there is not much different from unity, and thus we choose F ¼ 1.0 for all of the calculations reported here.…”

Section: Results For Threshold Presssuresmentioning

confidence: 99%

“…In many circumstances, 8,10,11,16 an exit coefficient is used to describe pressure recovery, which occurs between the glottal exit and the entrance to the vocal tract. Results presented in Table II of Ref. 8, which were based on pressure distributions 17,18 taken with the physical model M5, showed that the exit coefficients were small in comparison with the entrance loss coefficients, 12 and thus we set the exit coefficient k ex ¼ 0.…”

Section: A Glottal Aerodynamicsmentioning

confidence: 99%

“…[8][9][10][11] The pressure at the glottal entrance is connected with the pressure at the glottal exit P 2 by the Bernoulli equation,…”

Section: A Glottal Aerodynamicsmentioning

confidence: 99%

“…A recent study 7 showed that the key to resolving this discrepancy lies in recognizing that the entrance loss coefficient [8][9][10][11] is not constant at small half-widths but becomes large as the half-width becomes small. There it was also shown that a reasonable parameterization of this coefficient is…”

Section: Introductionmentioning

confidence: 99%

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Phonation threshold pressure and the elastic shear modulus: Comparison of two-mass model calculations with experiments

Fulcher

Scherer

Waddle

2012

The Journal of the Acoustical Society of America

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Ishizaka and Flanagan's classic two-mass model of vocal fold motion is applied to small oscillations where the equations become linear and the aerodynamic driving force is described by an effective stiffness. The solution of these equations includes an analytic formula for the two eigenfrequencies; this shows that conjugate imaginary parts of the frequencies emerge beyond eigenvalue synchronization and that one of the imaginary parts becomes zero at a pressure signaling the instability associated with the onset of threshold. Using recent measurements by Fulcher et al. of intraglottal pressure distributions [J. Acoust. Soc. Am. 129, 1548Am. 129, -1553Am. 129, (2011.] to inform the behavior of the entrance loss coefficients, an analytic formula for threshold pressure is derived. It fits most of the measurements Chan and Titze reported for their 2006 physical model of the vocal fold mucosa. Two sectors of the mass-stiffness parameter space are used to produce these fits. One is based on a rescaling of the typical glottal parameters of the original Ishizaka and Flanagan work. The second requires setting two of the spring constants equal and should be closer to the experimental conditions. In both cases, values of the elastic shear modulus are calculated from the spring constants.

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Section: Results For Threshold Presssuresmentioning

confidence: 99%

Section: A Glottal Aerodynamicsmentioning

confidence: 99%

“…[8][9][10][11] The pressure at the glottal entrance is connected with the pressure at the glottal exit P 2 by the Bernoulli equation,…”

Section: A Glottal Aerodynamicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Phonation threshold pressure and the elastic shear modulus: Comparison of two-mass model calculations with experiments

Fulcher

Scherer

Waddle

2012

The Journal of the Acoustical Society of America

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“…In Sec. II in the following text, it will be shown that Titze's assumption is reasonable for intermediate and larger glottal widths but that measurements 13,14 of the entrance loss coefficient at small glottal widths show a strong inverse dependence on these widths. To include this physical effect in the surface wave model, one must include an inverse n 0 term in the expression for the entrance loss coefficient as well as a constant term.…”

Section: Introductionmentioning

confidence: 87%

Phonation threshold pressure: Comparison of calculations and measurements taken with physical models of the vocal fold mucosa

Fulcher

Scherer

2011

The Journal of the Acoustical Society of America

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In an important paper on the physics of small amplitude oscillations, Titze showed that the essence of the vertical phase difference, which allows energy to be transferred from the flowing air to the motion of the vocal folds, could be captured in a surface wave model, and he derived a formula for the phonation threshold pressure with an explicit dependence on the geometrical and biomechanical properties of the vocal folds. The formula inspired a series of experiments [e.g., R. Chan and I. Titze, J. Acoust. Soc. Am 119, 2351-2362 (2006)]. Although the experiments support many aspects of Titze's formula, including a linear dependence on the glottal half-width, the behavior of the experiments at the smallest values of this parameter is not consistent with the formula. It is shown that a key element for removing this discrepancy lies in a careful examination of the properties of the entrance loss coefficient. In particular, measurements of the entrance loss coefficient at small widths done with a physical model of the glottis (M5) show that this coefficient varies inversely with the glottal width. A numerical solution of the time-dependent equations of the surface wave model shows that adding a supraglottal vocal tract lowers the phonation threshold pressure by an amount approximately consistent with Chan and Titze's experiments.

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Validation of a flow–structure-interaction computation model of phonation

Bhattacharya

Siegmund

2014

Journal of Fluids and Structures

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Computational models of vocal fold (VF) vibration are becoming increasingly sophisticated, their utility currently transiting from exploratory research to predictive research. However, validation of such models has remained largely qualitative, raising questions over their applicability to interpret clinical situations. In this paper, a computational model with a segregated implementation is detailed. The model is used to predict the fluid–structure interaction (FSI) observed in a physical replica of the VFs when it is excited by airflow. Detailed quantitative comparisons are provided between the computational model and the corresponding experiment. First, the flow model is separately validated in the absence of VF motion. Then, in the presence of flow-induced VF motion, comparisons are made of the flow pressure on the VF walls and of the resulting VF displacements. Self-similarity of spatial distributions of flow pressure and VF displacements is highlighted. The self-similarity leads to normalized pressure and displacement profiles. It is shown that by using linear superposition of average and fluctuation components of normalized computed displacements, it is possible to determine displacements in the physical VF replica over a range of VF vibration conditions. Mechanical stresses in the VF interior are related to the VF displacements, thereby the computational model can also determine VF stresses over a range of phonation conditions.

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Pressure distributions in a static physical model of the uniform glottis: Entrance and exit coefficients

Cited by 21 publications

References 10 publications

Phonation threshold pressure and the elastic shear modulus: Comparison of two-mass model calculations with experiments

Phonation threshold pressure and the elastic shear modulus: Comparison of two-mass model calculations with experiments

Phonation threshold pressure: Comparison of calculations and measurements taken with physical models of the vocal fold mucosa

Validation of a flow–structure-interaction computation model of phonation

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