Michael Triep 1 , Clemens Kirmse 1 , Michael Stingl 2 , Michael Döllinger 3 , Christoph Brücker 1

1 TU Bergakademie Freiberg, Institute of Mechanics and Fluid Dynamics, Freiberg

2 Universität Erlangen-Nürnberg, Institute of Applied Mathematics II, Erlangen

3 Universitätsklinikum Erlangen, Dept. of Phoniatrics and Pedaudiology, Erlangen

Clinical observations of the self-excited vocal folds in human probands during phonation allow a classification into several glottal opening modulation categories. In general, one distinguishes the healthy regular and other pathological irregular glottis closure types. A slight pathological change of the vocal fold's geometry and/or their movement may have already a strong effect on the flow field and thereby on the flow-induced noise (sources) which is a parameter that characterizes the voice quality (noise-to-harmonic ratio). In order to study the flow-dependent causes for the deterioration in voice quality, a realistic scaled-up three-dimensional (3-D) dynamic glottal cam model which has been already used in a previous study for regular glottal opening modulation situations is used. In this reference case the elliptic-shaped orifice opening cross section and a convergent - straight - divergent lateral and upward movement mimics the realistic time-varying cyclic motion of the healthy vocal folds and results in a realistic volume flow waveform profile.

Four different glottis closure types from clinical observations are mapped individually onto the membrane covered 3-D cam model considering a comparable maximum opening area for all, thus allowing us to differentiate deviations in the flow field from the reference case. The flow through the driven cam model is studied in water while keeping the most important flow parameters similar to the real situation. The advantages of this model are the enlarged time scales and the reproducible boundary conditions for cyclic measurements and visualizations of the flow. The large and small scale 3-D flow structures can be studied and compared in detail with numerical simulations. These aim to determine the harmonic and the noisy components of the flow-induced local source terms and the global noise-to-harmonic ratio, which will give insight to the mechanisms leading to deteriorated voice quality.

Willy Mattheus 1 , Stefan Zörner 2 , Manfred Kaltenbacher 2 , Rüdiger Schwarze 1 , Christoph Brücker 1 , Willy Mattheus 1

1 TU Bergakademie Freiberg, Institute of Mechanics and Fluid Dynamics, Freiberg

2 Alpen-Adria Universität Klagenfurt, Institute of Smart System-Technologies, Klagenfurt

For a three dimensional (3-D) model of the human vocal folds the time dependent transglottal flow field is computed numerically by solving the discretized incompressible Navier-Stokes equation. The model geometry is based on an existing up-scaled experimental 3-D dynamic glottal configuration for flow visualization purposes under reproducible conditions. The fluid used in the model is water. The flow is pressure driven while keeping the most important flow parameters similar to the real situation in human larynx. Typical glottal opening modulations observed in clinical studies and which have been mapped onto the membrane covered cams in the corresponding experimental set-up, are prescribed to the computational grid. The flow boundary conditions for the numerical simulation in the form of volume flow rate at the inlet and constant pressure over the outlet are set as in experiment. The flow field is computed with the finite volume CFD code OpenFOAM on parallel computer architecture. The flow downstream of several irregular glottal closure cases is studied and compared to the flow in the regular case. In addition, the 3-D time-dependent vortical flow structures are compared to experimental flow results. The coherent large-scale structures and stochastic small-scale structures are examined in more detail in order to determine their contribution to the global sound pressure spectrum. Based on Lighthill's acoustic analogy, the acoustic source term distributions and the sound propagation are numerically computed with the finite element code CFS . Since, in general, the quality of voice depends on the ratio of the noisy to the harmonic components; results from the present study are intended to help surgeons in the diagnostics and therapy of pathological vocal folds.

Ken-Ichi Sakakibara 1 , Hiroshi Imagawa 2 , Hisayuki Yokonishi 2 , Takao Goto 3 , Miwako Kimura 3,4 , Takaharu Nito 2 , Niro Tayama 3

1 Health Sciences Univ., Dept. Comm. Disorders, Sapporo

2 University of Tokyo, Dept. Otolaryngology, Tokyo

3 Intenational Medical Center of Japan, , Tokyo

4 UT Southwestern Medical Center, Dept. Otolaryngology, Dallas

Inspiratory phonation is the phonation during inhalation and in
general, it sometimes appear in laughing.  In this study, we analyze
vibratory patterns of reverse phonation using stereographic high-speed
imaging, EGG, and simulation by two-mass model with the supra- and
subglottal system.  In reverse phonation, mucosal waves of the vocal
folds were observed in the high-speed images and propagated from the
top to the bottom (from lateral to center). The vocal fold oscillation
is easy in fry and falsetto registers. In modal register, the vocal
fold osicllation is often unstable in human and simulation.

Jaromír Horáček 1 , Václav Uruba 1 , Vojtěch Radolf 1 , Vaclav Uruba 1 , Petr Šidlof 1 , Jan Veselý 1 , Vítězslav  Bula 1

1 Institute of Thermomechanics, Academy of Sciences, Prague