Tuesday January 23, 2018 Q&A

What happens to owls’ sense of hearing as they get older?


1 It improves

2 It does not change

3 It gets worse

The correct answer is 2: it does not change.

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As humans get older, we gradually lose our sense of hearing, although this varies from one person to the next. Hearing loss is most common in the high frequencies, above 8 kHz, which means we cannot hear high-pitched sounds. This condition, which is called presbycusis, occurs when the outer hair cells on the cochlea deteriorate. These are the cells that help our inner ear amplify and distinguish between the sounds it receives.

Hearing loss does not just affect humans: it has also been observed among other mammals, such as mice, chinchillas and gerbils. What about other animals? Apparently not. Studies have shown that fish, amphibians and birds are able to produce hair cells throughout their lives, so they can replace damaged ones. As a result, they should not experience any hearing loss as they get older.

To verify this hypothesis, researchers at the University of Oldenburg in Germany looked at the barn owl, a bird of prey known for its keen sense of hearing. In their study, the scientists gave seven barn owls of varying ages a hearing test. The birds were trained to land on a perch when they heard a sound, in exchange for some food. The researchers used this approach to test the birds' entire auditory range. They found no significant difference between the auditory perception of the youngest barn owls and the oldest one – which was 23 years old. (In nature, barn owls do not normally live to such a ripe old age; their normal life span is three to four years.) These findings corroborate a prior study that looked at age-related hearing loss in European starlings.

The authors of the latest study eventually hope to learn more about how animals regenerate hair cells in order to come up with new ways of treating hearing loss in humans.


Source: Proceedings of the Royal Society of London B