Age-related hearing loss: Do birds hold the key to finding a cure?
New research shows that barn owls keep their hearing into old age. Learning more about how this can happen, could help researchers better understand how hearing works. Is this a step in the right direction to finding a cure to age-related hearing loss in humans?
“Barn owls have ageless ears,” according to scientists at the University of Oldenburg, Germany, who recently published a study in the journal, Royal Society Proceedings B, under the same name. According to researchers who trained seven barn owls to fly to a perch to receive a reward in response to specific sounds, the birds have remarkable capacity for regeneration of hair cells, which protects them from age-related hearing loss (presbycusis).
What did they find?
The researchers analyzed how the barn owls responded to sounds at different intensities, ranging from ‘inaudible to humans’ to sounds corresponding to ‘soft whispers’. The results showed that, when compared to the younger owls, the older owls had little or no hearing loss. Even a 23-year-old owl that took part in the study showed no signs of age-related hearing loss. Interestingly, barn owls in the wild typically only live to the age of three or four. Twenty-three is extremely old for this type of bird.
Birds, in general, show a remarkable capacity to regenerate hair cells in the basilar papilla (the auditory sensory organ of birds, lizards, and amphibians. This is the equivalent of the Corti, the receptor organ for hearing, which is located in the cochlea in mammals.) Therefore, the ability to regenerate hair cells is why birds are naturally protected from age-related hearing loss.
“The ability to regenerate hair cells is why birds are naturally protected from age-related hearing loss.”
It appears that at some point in evolution, mammals lost these regenerative abilities. Humans, like all mammals, commonly suffer from hearing loss in old age. By the age of 65, humans can expect to lose more than 30dB in sensitivity at high frequencies.
Who has age-related hearing loss?
In the UK, age-related hearing loss (presbycusis), affects an estimated 40 percent of adults aged over 50, and more than 70 percent of people aged over 70 years of age. Estimates in the United States show that approximately one in three people between the ages of 65 and 74 has hearing loss, and nearly half of those older than 75 have difficulty hearing.
How can you tell if you have a hearing problem?
Here’s a quick test for you to try. If you answer ‘yes’ to three or more of these questions, you may have a hearing problem and you may benefit from having a hearing test.
- Do you sometimes feel embarrassed when you meet new people because you struggle to hear?
- Do you feel frustrated when talking to members of your family because you have difficulty hearing them?
- Do you have difficulty hearing or understanding co-workers, clients, or customers?
- Do you feel restricted or limited by a hearing problem?
- Do you have difficulty hearing when visiting friends, relatives, or neighbors?
- Do you have trouble hearing in the movies or in the theater?Does a hearing problem cause you to argue with family members?
- Do you have trouble hearing the TV or radio at levels that are loud enough for others?
- Do you feel that any difficulty with your hearing limits your personal or social life?
- Do you have trouble hearing family or friends when you are together in a restaurant?
*Questions adapted from: Newman, C.W., Weinstein, B.E., Jacobson, G.P., & Hug, G.A. (1990). The Hearing Handicap Inventory for Adults [HHIA]: Psychometric adequacy and audiometric correlates. Ear Hear, 11, 430-433.
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