Military personnel, industrial workers and students who listen to their iPods at top volume are helping scientists discover whether vitamins and minerals can reverse hearing loss.

In the past it was thought only earplugs could protect the inner ear against loud noises whereas it is believed to be down to molecular changes that cause sound-sensitive hair follicles to shut down.

During guinea pig trials at the University of Michigan Kresge Hearing Research vitamins and a mineral appeared to block 80 per cent of hearing impediment from loud noises.

Now clinical trials of the vitamins A, C and E plus mineral magnesium have been launched in Sweden, Spain and the US to investigate the affect on humans.

Assistant Professor of otolaryngology at the University Glenn Green said: "When we can’t prevent noise-induced hearing loss through screening programs and use of hearing protection, then we really need to come up with some way of protecting people who are still going to have noise exposure."

The National Insitutes of Health says noise from motorcycles, firecrackers and small firearms – emitting sounds from 120 to 150 decibels – can cause noise-induced hearing loss.