The human voice comes from a complex interaction between the flexible vocal folds and the transient glottal jet induced by air forced by the diaphragm through the glottis. Traumatized vocal folds disrupt speech and little is known how to efficiently recover the lost voice. First-principles, three-dimensional simulations of the dynamic vocal folds coupled to the unsteady, turbulent motion of the air past them, and resulting acoustic field from the nose and mouth, will guide voice recovery methods by quantitatively determining the acoustic source and by utilizing a new multi-physics optimization methodology to find effective methods of recovering lost voice via vocal fold augmentation. Realistic geometries taken from newly acquired static and dynamic MRI data, along with corresponding acoustic measurements, will provide validation. Results from predictive and controlled vocal fold simulations will provide new and complete information on human voice production, guidance for restoring the voice after its loss, and low-order, approximate dynamical models of phonation and its sensitivity to vocal fold modification.
The numerical datasets, their reduced order descriptions, and the validation data will provide a reliable database on which to build cross-cutting biomedical investigations of brain-speech coupling using functional MRI as well as showing a path towards patient-specific vocal fold restorative surgeries. The new adjoint-based optimization methodology is applicable to a broad class of flows beyond phonation, including optimization of highly flexible bio-inspired engineering systems, biological sonation, and boundary layer control.
The work will also be the central theme in a multi-level education program. The fluid-structure optimization methodology will be incorporated into graduate level instruction while simplified fluid-structure interaction algorithms will be brought into an undergraduate course on numerical algorithms through mini-projects using problem-based learning. Summer undergraduate research experience through NSF and NASA programs will be used to attract and retain engineering students from under-represented groups. Further, human phonation and biological sonation will be central themes in STEM K-12 outreach programs: one based at the University of Illinois and one part of a larger, national STEM effort. The outreach programs are aimed at high school students and culminate with the students building a mechanical larynx and seeing for themselves the process of phonation.
