Abstract:The enormous computational power and time required for simulating the complex phonation process preclude the effective clinical use of computational larynx models. The aim of this study was to evaluate the potential of a numerical larynx model, considering the computational time and resources required. Using Large Eddy Simulations (LES) in a 3D numerical larynx model with prescribed motion of vocal folds, the complicated fluid-structure interaction problem in phonation was reduced to a pure flow simulation wit… Show more
“…As described by Sadeghi et al (2018), there must be a small area between both vocal folds of 0.5 mm 2 at GC1 to reach a numerically stable simulation. Nevertheless, this small gap still interrupts the flow through the glottis during the closed phase, as shown by Sadeghi et al (2019b). For GC2, GC3, and GC4, the initial glottal gaps possess a triangular and for GC5 a rectangular shape, see Figure 3.…”
For the clinical analysis of underlying mechanisms of voice disorders, we developed a numerical aeroacoustic larynx model, called simVoice, that mimics commonly observed functional laryngeal disorders as glottal insufficiency and vibrational left-right asymmetries. The model is a combination of the Finite Volume (FV) CFD solver Star-CCM+ and the Finite Element (FE) aeroacoustic solver CFS++. simVoice models turbulence using Large Eddy Simulations (LES) and the acoustic wave propagation with the perturbed convective wave equation (PCWE). Its geometry corresponds to a simplified larynx and a vocal tract model representing the vowel /a/. The oscillations of the vocal folds are externally driven. In total, 10 configurations with different degrees of functional-based disorders were simulated and analyzed. The energy transfer between the glottal airflow and the vocal folds decreases with an increasing glottal insufficiency and potentially reflects the higher effort during speech for patients being concerned. This loss of energy transfer may also have an essential influence on the quality of the sound signal as expressed by decreasing sound pressure level (SPL), Cepstral Peak Prominence (CPP), and Vocal Efficiency (VE). Asymmetry in the vocal fold oscillations also reduces the quality of the sound signal. However, simVoice confirmed previous clinical and experimental observations that a high level of glottal insufficiency worsens the acoustic signal quality more than oscillatory left-right asymmetry. Both symptoms in combination will further reduce the quality of the sound signal. In summary, simVoice allows for detailed analysis of the origins of disordered voice production and hence fosters the further understanding of laryngeal physiology, including occurring dependencies. A current walltime of 10 h/cycle is, with a prospective increase in computing power, auspicious for a future clinical use of simVoice.
“…As described by Sadeghi et al (2018), there must be a small area between both vocal folds of 0.5 mm 2 at GC1 to reach a numerically stable simulation. Nevertheless, this small gap still interrupts the flow through the glottis during the closed phase, as shown by Sadeghi et al (2019b). For GC2, GC3, and GC4, the initial glottal gaps possess a triangular and for GC5 a rectangular shape, see Figure 3.…”
For the clinical analysis of underlying mechanisms of voice disorders, we developed a numerical aeroacoustic larynx model, called simVoice, that mimics commonly observed functional laryngeal disorders as glottal insufficiency and vibrational left-right asymmetries. The model is a combination of the Finite Volume (FV) CFD solver Star-CCM+ and the Finite Element (FE) aeroacoustic solver CFS++. simVoice models turbulence using Large Eddy Simulations (LES) and the acoustic wave propagation with the perturbed convective wave equation (PCWE). Its geometry corresponds to a simplified larynx and a vocal tract model representing the vowel /a/. The oscillations of the vocal folds are externally driven. In total, 10 configurations with different degrees of functional-based disorders were simulated and analyzed. The energy transfer between the glottal airflow and the vocal folds decreases with an increasing glottal insufficiency and potentially reflects the higher effort during speech for patients being concerned. This loss of energy transfer may also have an essential influence on the quality of the sound signal as expressed by decreasing sound pressure level (SPL), Cepstral Peak Prominence (CPP), and Vocal Efficiency (VE). Asymmetry in the vocal fold oscillations also reduces the quality of the sound signal. However, simVoice confirmed previous clinical and experimental observations that a high level of glottal insufficiency worsens the acoustic signal quality more than oscillatory left-right asymmetry. Both symptoms in combination will further reduce the quality of the sound signal. In summary, simVoice allows for detailed analysis of the origins of disordered voice production and hence fosters the further understanding of laryngeal physiology, including occurring dependencies. A current walltime of 10 h/cycle is, with a prospective increase in computing power, auspicious for a future clinical use of simVoice.
“…The effects of supraglottal structures as ventricular folds or characteristic geometrical conditions associated with specific vowels (pharyngeal constrictions and partially obstructed channel exits) were neglected. Previous studies have shown that the presence of the ventricular folds significantly reduces the phonation threshold pressure as long as their positions and the gap in between is optimally selected [35,44,45]. Furthermore, the acoustical driving effect of vocal tract resonances was minimized.…”
In voice research, analytically-based models are efficient tools to investigate the basic physical mechanisms of phonation. Calculations based on lumped element models describe the effects of the air in the vocal tract upon threshold pressure (Pth) by its inertance. The latter depends on the geometrical boundary conditions prescribed by the vocal tract length (directly) and its cross-sectional area (inversely). Using Titze’s surface wave model (SWM) to account for the properties of the vocal folds, the influence of the vocal tract inertia is examined by two sets of calculations in combination with experiments that apply silicone-based vocal folds. In the first set, a vocal tract is constructed whose cross-sectional area is adjustable from 2.7 cm2 to 11.7 cm2. In the second set, the length of the vocal tract is varied from 4.0 cm to 59.0 cm. For both sets, the pressure and frequency data are collected and compared with calculations based on the SWM. In most cases, the measurements support the calculations; hence, the model is suited to describe and predict basic mechanisms of phonation and the inertial effects caused by a vocal tract.
“…During postnatal vocal development, gradual body changes, such as lung growth or VF stiffness in marmosets (46,47) or increased muscle speed in songbirds (48), can drive changes in vocal 180 behavior. Embodied human VF models have direct clinical relevance to pathological physical behaviors with abnormal vocal output (1) and patient specific model-assisted phonosurgery (49,50), because most laryngeal human voice disorders are caused by changes in VF geometry, structural integrity, or kinematics (4). The embodied approach to voice production as presented here thus improves our understanding how neural mechanisms and biomechanics interact to 185 drive vocal behavior in vertebrates.…”
Section: Main Textmentioning
confidence: 99%
“…Causally linking descending motor control to voiced sound production requires 50 computational biophysical models to explore the multidimensional control space (13), which the brain also learns to navigate. Particularly high-fidelity continuum models that include the full fluid-structure-acoustics interaction (FSAI) complexity of voiced sound production in anatomically realistic geometries of vocal fold and tract (4,(14)(15)(16)(17)(18)(19) are essential to develop when realistic representations of voice physiology and biomechanics are essential, such as in the 55 clinical management of voice disorders (1), or understanding motor control of voice (20,21) or (bird)song (22).…”
20Voiced sound production is the primary form of acoustic communication in terrestrial vertebrates, particularly birds and mammals, and including humans. Developing a causal physics-based model that links descending vocal motor control to tissue vibration and sound, requires embodied approaches that include realistic representations of voice physiology. Here we first implement and then experimentally test a high-fidelity three-dimensional continuum model 25 for voiced sound production in birds. Driven by individual-based physiologically quantifiable inputs, combined with non-invasive inverse methods for tissue material parameterization, our model accurately predicts observed key vibratory and acoustic performance traits. These results demonstrate that realistic models lead to accurate predictions supporting the continuum model approach as a critical tool towards a causal model of motor control of voiced sound production. 30
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