14 DAY TRIAL // A team of experts has produced a new mathematical model to explain how vocal folds produce sounds and speech. This may help other researchers develop better prosthetic devices for people who find it difficult to speak, or who have problems doing so on account of disorders affecting their larynx.
Most people take vocalization and speech for granted, and continue to do so throughout their lives, without giving this ability a second thought.
But this is not valid for people suffering from conditions such as vocal fold paralysis, or who have impaired speech patterns.
Members in the research team that produced the model also suffer from such conditions. The expert group includes George Washington University (GWU) Biofluid Dynamics Laboratory engineering professor Michael Plesniak and post-doctoral researcher Byron Erath.
University of Waterloo professor Sean Peterson is also a part of the team. Together, the researchers developed a fully-fledged mechanical model of human vocal folds, which they presented yesterday, November 21, at the American Physical Society's (APS) Division of Fluid Dynamics (DFD) meeting.
One of the main conclusions in the new investigation was the fact that the airflow which impacts the vocal folds differs in terms of symmetry between healthy people and those suffering for various disorders in the larynx.
“Potential application of this finding includes assisting otolaryngologists to optimize surgical procedures to correct vocal fold paralysis with an implant that changes the position of the damaged vocal fold,” Plesniak explains.
He says that the vocal folds are structures stretched across the larynx, which are “driven” by air expelled from the lungs. As air flows past them, the folds vibrate, producing sounds. The folds are unique to each individual, which is why no two voices sound the same.
In the new study, the group learned that, if an asymmetric air flow develops in the larynx, then the flow passing around one vocal fold can move to the other, producing disturbances in the pressures that drive the latter. The consequences are devastating in terms of speech capabilities.
“In the past, many investigators have assumed air flow is symmetrical over the vocal folds. We’ve discovered that this is not always the case,” explains Erath, quoted by Science Blog.
The team believes that one of the main directions of development in research aimed at curing speech generation disorders is to develop synthetic materials that replicate the vocal folds. This could ensure that correct air flow is restored, and that sounds are easily produced.
However, the researchers admit that some time will pass before practical applications can be considered. But, in the future, we can expect to see an artificial larynx, or an entire voice apparatus, being produced synthetically.