Researchers at The University of Toledo and Bowling Green State University are excited to tout what they believe is the first large-scale model of human vocal folds that has an extensive range of motion.
Dr. Kenneth DeWitt, University Distinguished Professor of Chemical and Environmental Engineering, said the model of the vocal folds has been constructed to be "dynamically similar" to the real situation. And Dr. Ronald Scherer, a professor in the communication disorders department at BGSU, said, "In the modeling of phonation there's never been such a good model as this. There's never been a model worldwide that has that kind of motion."
DeWitt said the model is seven and a half times larger than real vocal folds in order to enable the visualization of air flow patterns that occur in the glottis when the vocal folds are moving at different frequencies.
According to DeWitt, his expertise for the model is in analytical and experimental fluid mechanics; Scherer's is phonation and voice mechanics; and Dr. Terry Ng, UT professor of mechanical, industrial and manufacturing engineering, lent his considerable knowledge in experimental fluid mechanics. In addition, Bogdan Kucinschi, a UT doctoral student, played a vital role in the project, which is his dissertation topic in mechanical engineering. "It's probably the mixture of backgrounds of the individuals that makes this collaborative effort come together," DeWitt said.
Kucinschi explained, "This model took a lot of time to create. All of the pieces work in very low tolerances. We can adjust it for different setups. This will help us understand better how speech is produced. For example, if something is going wrong in the larynx due to a disease, what's the impact on speech? We can interpret the speech effort in terms of vocal pressure. Just like in speech, we can adjust the frequency at which the folds are moving. As far as we know, it's the only model in the world that can simulate experimentally the moving folds." He said other models are somewhat restrictive.
Kucinschi added, "This model helps us to understand the mechanics by which sounds are produced by the larynx. A small change in glottal radius can yield a big difference in speech characteristics. With the model it's the same situation. We can simulate different geometrical arrangements and the impact they have on speech. This is very important for research."
Scherer started at BGSU in 1996 and wrote a grant to study the mechanics of phonation. "In the process of doing that grant, I was interested in acquiring colleagues. Ken DeWitt had done some work configuring flow in the lungs that was similar to our work with the larynx. We got in touch with each other and started our collaboration. We've had a number of students from UT do their thesis. Bogdan came on board, and he's been working very diligently. It's been a wonderful collaboration."
Scherer is the principal investigator on the project, which is funded through a four-year, $2.5 million grant through the National Institutes of Health; the researchers are two years into the grant.DeWitt said the research would not sit on the shelf because it has "real-life applications."
The researchers plan to make a presentation on the model at the International Conference on Voice Physiology and Biomechanics in Marseille, France, in August.