Some people have hairy ears, but everyone has so-called hair cells in their ears. The key to hearing, these cells sport hairlike projections named stereocilia, which bend in response to sound waves. Scientists have now discovered that stereocilia are in a state of continuous regeneration. Each projection seems to replace its molecular components every 48 hours.
The researchers, who report their work in the Aug. 22 Nature, suggest that their finding may explain why it takes a day or so for normal hearing to return after exposure to abnormally loud sounds, such as music at a rock concert.
"Every 2 days, the whole stereocilia seems to renew its backbone. That time-course is comparable to the time-course of recovery from temporary hearing loss," says coauthor Bechara Kachar of the National Institute on Deafness and Other Communication Disorders in Bethesda, Md.