Why Birds Don’t Lose their Hearing
Scientists have discovered that birds do not lose their hearing as they age. Whilst our hearing begins to deteriorate when sensory cells in our ears die off, barn owls can regenerate those cells. It is thought that all birds might possess the same ability. This finding could lead to new treatments for deafness in humans and mammals.
New Study of Barn Owls
A new study of barn owls by the University of Oldenburg in Germany has found that they have ageless ears. They are able to regenerate their cochlea and it is this ability which is likely to be the reason that they retain their hearing. The cochlea features sensory cells called hair cells and hearing loss is often linked to damage of these particular cells. Such damage can be caused by exceptionally loud noises or through ageing. Should it prove possible to understand how birds regenerate the cochlea, this knowledge could be used to protect people against hearing loss or even to reverse it.
Do All Birds Have Ageless Ears?
A previous study of starlings produced similar results as did research by the University of Virginia into chickens. It is likely that most or all birds retain their hearing throughout their lives.
By the age of 65, humans have typically lost more than 30 decibels in sensitivity at high frequencies. Most mammals suffer some hearing loss as they age. But the barn owls studied had experienced little or no hearing loss. During the study the researchers looked at the responses to sound of seven birds. Four were young and three were elderly. They were placed in sound chambers where pure tones lasting 3000 milliseconds were delivered at different frequencies from 0.5 to 12 kHz.
There were no differences between the responses of the two age groups. The researchers also tested the hearing of a 23-year-old barn owl on three occasions during its life and found no deterioration in its hearing.
Many questions remain and further research will be required but the findings offer hope that one day it will be possible to cure deafness in humans and even in our treasured pets. "Bird brains" may be a derogatory term but it looks "bird ears" ought to be a compliment!