14 DAY TRIAL // Researchers in Utah and Texas have recently announced the discovery of a new sound-amplification system in the ear, made up of tiny, hair-like tubes atop “hair cells” in the auditory canal. These devices apparently function just like “flexoelectric motors,” which are the ones that drive, for example, the power steering in cars. When faint sounds reach them, they begin to move back and forth, thus mechanically amplifying the sounds. After the amplification stage of hearing, the hair cells in the cochlea take over and convert sound vibrations into electrical impulses for the brain.
“We are reporting discovery of a new nanoscale motor in the ear. The ear has a mechanical amplifier in it that uses electrical power to do mechanical amplification. It's like a car's power steering system. You turn the wheel and mechanical power is added. Here, the incoming sound is like your hand turning the wheel, but to drive, you need to add power to it. These hair bundles add power to the sound. If you did not have this mechanism, you would need a powerful hearing aid,” University of Utah College of Engineering Chair of Bioengineering, Professor Richard Rabbitt explained.
He is also the principal author of a new scientific paper detailing the find, to be published today (April 22nd) in the Public Library of Science's journal PLoS One. University of Utah bioengineering doctoral student Katie Breneman has been the first author of the new research, which has also been co-authored by Houston-based Baylor College of Medicine Otolaryngology Professor William Brownell. The experts believe that flexoelectricity could also be involved in a number of other processes inside the human brain, including food processing and memory formation and storing.
“Dancing hairs help you hear. [Our research ]suggests sensory cells in the ear are compelled to move when they hear sounds, just like a music aficionado might dance at a concert. In this case, however, they'll dance in response to sounds as minuscule as the sound of your own blood flow pulsating in your ear,” Breneman shared.
“There is some evidence that dendrites and axons change their diameter during intracellular voltage changes, and that could well have flexoelectric origins. Any time you have a membrane with small diameter – like in axons, dendrites and synaptic vesicles [located between nerve cells], there will be large flexoelectric forces and effects. Therefore, the flexoelectric effect may be at work in things like learning and memory. But that's pretty speculative,” Rabbitt added.