Try to go one week without speaking. Now, imagine going months, or years, without being able to talk to friends or loved ones.
For patients with severe voice disorders, the loss of their voice often means losing their social life, self esteem or livelihood. While existing therapies can treat mild to moderate voice disorders, physicians have a harder time determining effective treatments for those with severe cases.
With a new five-year, $2.5 million grant from the National Institute on Deafness and Other Communication Disorders at the National Institutes of Health, University of Cincinnati (UC) researchers will continue interdisciplinary partnerships to study the causes behind those disorders and the most effective ways to treat them.
The grant, awarded to laryngologist Sid Khosla, MD, of UC's department of otolaryngology, includes aerospace engineer Ephraim Gutmark, PhD, of engineering and otolaryngology, Suzanne Boyce, PhD, of communication sciences & disorders and Shanmugam Murugappan, PhD, of otolaryngology.
The researchers are seeking to prove a new hypothesis about the production of voice: that vortices, or pockets of rotating air near the vocal cords, are necessary for normal voice production. It is the modification or suppression of those vortices in laryngeal disease, researchers think, that leads to abnormal voice.
In normal voice production, or phonation, says Khosla, vocal cords come together while air flowing over them produces vibration. But he says researchers haven't been able to confirm exactly how the air creates the vibration.
Past research points to vortices as the key ingredient. Vortices were known to produce sound in jet engines and suction in tornados, but it wasn't until Khosla and Gutmark developed a method to identify vortices in a larynx that they could measure the forces they produced.
In that research, the team brought in techniques Gutmark had used to study airflow inside jet engines, when the goal was reducing jet noise.
"Now our purpose is different, but the physics is the same," says Gutmark. "Once you understand how airflow structure produces acoustics, you can either make the acoustics quieter, for jets, or make them stronger, for voices."
Khosla and his team will now study how vortices are affected in certain voice pathologies.
Specifically, they will look at treatments for unilateral vocal cord paralysis, a condition that often results in reduced vibrations of the paralyzed vocal cord.
"Often the paralyzed cord is in a position off midline," says Khosla, "so there is a gap between the cords during phonation. This will lead to altered vibration of the paralyzed side or both sides. Altered vibration gives altered sound."
If one of the tested treatments sufficiently restores vortices in the airway, then it could stand the best chance of restoring normal vibrations - and normal voice.
"It's not only about determining that these vortices are there and they play a crucial role," says Khosla, "but it's also about determining the best ways to restore them for these patients."