Material and shape optimization for multi-layered vocal fold models using transient loadings

Abstract

Commonly applied models to study vocal fold vibrations in combination with air flow distributions are self-sustained physical models of the larynx consisting of artificial silicone vocal folds. Choosing appropriate mechanical parameters and layer geometries for these vocal fold models while considering simplifications due to manufacturing restrictions is difficult but crucial for achieving realistic behavior. In earlier work by Schmidt et al. [J. Acoust. Soc. Am. 129, 2168-2180 (2011)], the authors presented an approach in which material parameters of a static numerical vocal fold model were optimized to achieve an agreement of the displacement field with data retrieved from hemilarynx experiments. This method is now generalized to a fully transient setting. Moreover in addition to the material parameters, the extended approach is capable of finding optimized layer geometries. Depending on chosen material restriction, significant modifications of the reference geometry are predicted. The additional flexibility in the design space leads to a significantly more realistic deformation behavior. At the same time, the predicted biomechanical and geometrical results are still feasible for manufacturing physical vocal fold models consisting of several silicone layers. As a consequence, the proposed combined experimental and numerical method is suited to guide the construction of physical vocal fold models.

Flow-induced oscillations of vocal-fold replicas with tuned extensibility and material properties

“…Today, the development of improved vocal-fold replicas and enriched experiments is still necessary to better understand the complexity of the multiphysical couplings involved, on the one hand, and to evaluate and dialogue with the various theories and numerical models mentioned above, on the other hand. Thus, in recent years, while improving current manufacturing procedures 45 , 46 , the search for optimal materials 47 – 49 , multi-scale structures 49 and mechanical control 50 , 51 for increasingly “bio-/phono-mimetic” vocal-fold replicas is the subject of active investigation. However: Even though vocal-fold stretching is a major aspect of phonation biomechanical control 3 , 32 – 35 , 39 , 52 , 53 , the number of in vitro studies involving experimental models of vocal folds able to measure and control the laryngeal longitudinal pre-strain occurring before any phonatory event is very limited.…”

A one-dimensional flow model enhanced by machine learning for simulation of vocal fold vibration

“…On the other hand, the unknown tissue properties for individual subjects, which can not be identified from current imaging technologies, limit the application of patient-specific modeling. There have been prior efforts to derive the vocal fold tissue properties using finite-element method (FEM) based models combined with experimental tests [21,22,23], but they were limited to ex-vivo conditions. Although it is probable to determine the in-vivo, subject-specific tissue properties by running the high-fidelity FSI simulations and solving an inverse problem, assuming that all other aspects in the FSI model match the corresponding in-vivo experiment (e.g., the anatomy and boundary conditions), such an approach is still not practical since the 3D airflow simulation is too expensive even with high-performance parallel computing.…”