Among the sometimes bothersome things about being a hearing specialist is that many of the circumstances we encounter that have caused our patients to lose their hearing can’t be reversed. Damage to the tiny, sensitive hair cells of the inner ear is one of the more common reasons for hearing loss. The work of these hair cells is to vibrate in response to sounds. Our sense of hearing is the result of these vibrations being converted into electrical energy and transmitted to the brain for decryption.
The fact is that, the same sensitivity of these hair cells that allows them to respond to sounds and translate them into electrical impulses that our brains perceive as hearing also makes them fragile, and susceptible to damage. This damage may occur due to aging, certain medications, infections, and by extended exposure to high-volume noises, resulting in noise-induced hearing loss, or NIHL. Once these hair cells are damaged in human ears, science has as yet not found a way to repair or “fix” them. As a result, hearing specialists and audiologists have to deal with hearing loss technologically, using hearing aids or cochlear implants.
This would not be the case if humans were more like fish and chickens. Although this may sound bizarre, it’s true, because unlike humans, some species of birds and fish can regenerate the hair cells in the inner ear if they become damaged, and thus regain their normal hearing. Chickens and zebra fish are just two examples of species that have the capacity to automatically replicate and replace their damaged inner ear hair cells, thus permitting them to fully recover from hearing loss.
While it is important to mention at the outset that the following research is in its early stages and that no practical benefits for humans have yet been achieved, significant breakthroughs in the treatment of hearing loss may come in the future from the groundbreaking Hearing Restoration Project (HRP). The not for profit organization, Hearing Health Foundation, is currently sponsoring research at laboratories in the United States and Canada Scientists involved in the HRP are trying to identify the compounds that allow the hair cells in certain animals to duplicate themselves, with the future goal of finding some way to enable human inner ear hair cells to do the same.
Because there are so many different compounds involved in the regeneration process – some that assist in replication, some that impede it – the scientists’ work is slow and difficult. Researchers are hopeful that what they learn about inner ear hair cell regeneration in avian or fish cochlea can later be applied to humans. The researchers in the various HRP labs are following different approaches to the problem, some working on gene therapies, others working on the use of stem cells, nevertheless all share the exact same goal.
Our entire office extends to them our best wishes and hopes for their success, because absolutely nothing would delight us more than being able to someday fully reverse our clients’ hearing loss.