A Possibility for Restoring Hearing Loss
When dealing with issues related to hearing health, there are a variety of physical technologies that can help address hearing loss, including implants and hearing aids
Hair Cells in the Ear
More than 15 years ago, doctors working at the University of Washington’s Merrill Bloedel Hearing Research Center developed a new method of treating hearing loss. Dr. Edwin Rubel, professor of Otolaryngology began investigating the regenerative properties of hair cells in the ear. Realizing that these “hairs” are actually a kind of special cell with a hair-like protrusion made out of protein, Dr. Rubel began researching their regenerative capabilities. These special cells with their protein-based protrusions respond to sound waves entering the ear canal. When the “hairs” are stimulated they translate their motion into electrical signals which are then sent down to the cochlear nerve. It is these translated mechanical signals that are used by the brain to understand and perceive sound.
Dr. Rubel’s team knew that many forms of hearing health disorders, including problems associated with aging, exposure to loud noises, and congenital defects were observed directly in the ear by a loss of these special cells with protein-based protrusions. For many decades, it was believed that if these “hairs” were destroyed or damaged that the associated hearing loss was permanent. But what Dr. Rubel discovered was that similar cells in the ears of birds were able to regenerate.
“We were quite astounded by this discovery,” said Dr. Rubel. “Our original research was predicated on the belief that once these special cells were damaged or destroyed that the results were permanent. That’s why hearing health issues were long believed to be irreversible.”
Dr. Rubel’s discovery, made in conjunction with concurrent research from other institutions, that these special hearing cells had the potential to regenerate kindled a new wave of research in the hearing health field.
The Future of Hearing Health Research
Right now, individuals who are suffering hearing health issues rely on technological devices to amplify sounds. Therapies like implants connected directly to the cochlear nerve work by using computer algorithms to translate vibrations into electrical signals that can be interpreted by the brain, effectively replicating the work that the “hairs” in the ear canal perform for people with good aural health.
“There’s been some truly wonderful accomplishment to help people dealing with hearing health issues,” said Dr. Rubel. “But before we can arrive at something approaching a real cure, we have to conduct more research on these special “hair” type cells in the ear.”
Thanks to the efforts of Dr. Rubel and other scientists in the audiology field, it is now understood that a wide variety of animals can spontaneously regenerate the special “hair” cells in their ears. Only mammals seem unable to regenerate the hearing protein-based “hair” cells. Dr. Rubel is currently focusing his attention on better understanding the “hair” cells and how they regenerate in other animals in order to stimulate the same process in human beings.
“Once we have more information about how birds manage this trick, we hope to use this data to transfer this knowledge to human beings,” said Dr. Rubel.
Other Avenues of Exploration
Expanding the scope of his research, Dr. Rubel is also spending time investigating how the central nervous system translates and interprets electrical signals. Dr. Ruben is interested in better understand how the brain works, exactly how sound waves are interpreted, and what factors influence and shape how the brain creates a coherent understanding of sounds.
Right now Dr. Rubel and his team are investigating how one species of bird – the Bengalese finch – overcomes hearing health issues. This species of bird is unique in that it learns to sing only a single melody in its life. When the bird experiences trauma to its ability to hear, it predictably has difficulty in singing its unique melody. Dr. Rubel and his team were able to demonstrate that after the “hair” cells in its ears regenerated, the bird regains its full ability to sing its own melody with absolutely no degradation in quality. This has convinced the scientists that Bengalese finches have a template for their personal melodies that are stored somewhere in their brains.
It is this kind of interesting research which drive’s Dr. Rubel’s passion for investigating hearing health issues, a career he has pursued for more than 40 years. And yet it is the tangible outcomes that can result from his scientific research that matters most to the doctor.
“If my team and I are able to crack the secret to curing hearing health issues, it would be a tremendous accomplishment,” said the UW professor. “I recognize that we would have never made so much progress if it weren’t for my esteemed colleagues here at UW. Some of the biggest contributors to my research are working just steps away from my lab. I am very grateful for all the help that my colleagues have given as it has proven immensely valuable in our research.”