Scientists have formulated a pill that could prevent or even reverse hearing loss caused by loud noise.
Clinical trials of the pill are about to start, but early research suggests it can reverse the damage up to three days after it occurs. Noise-induced hearing loss is the most common reason people lose their hearing. It has been estimated that 15 per cent of those between the ages of 20 and 60 have hearing loss caused by personal stereos, rock concerts or factory machinery. The damage can be caused by a single exposure to a very loud noise, such as an explosion, but more often it is caused by continuous or chronic exposure to loud sounds over time.
Exposure to these affects the delicate hair cells in the ear. The cells convert sound into electrical signals which then travel to the brain. Once damaged, hair cells cannot grow back, so hearing is reduced. One theory is that the force of vibrations from the noise damages the cells. The new pill is based on the idea that these vibrations cause the release of destructive molecules called free radicals into the bloodstream. These free radicals damage the hair cells.
Researchers had thought that antioxidants - chemicals that protect against this cell damage - might prevent hearing loss only if the antioxidants were given before noise exposure.
But research at Michigan University has shown that when the antioxidants were given up to three days after noise exposure, hearing loss was significantly reduced.