PhotoAs humans age, their hearing tends to degrade. Years of exposure to noise will take its toll on the delicate instrument that is the human ear.

The baby boom generation is now experiencing this. Not only has society generally become noisier over the last 40 years but all those years of rock concerts and headphone-listening too often means boomers don't hear as well as they enter their 60s.

For years, treatment for hearing loss consisted mostly of hearing aids. In 1984 the Food and Drug Administration (FDA) approved the first Cochlear implant, a surgically implanted electronic device that provides a sense of sound to someone who has lost almost all hearing. It's a very expensive procedure.

Miracle drug?

It may not be long, however, before there are approved drugs that will treat hearing loss before it can occur. Pfizer, Novartis and many other large pharmaceutical firms are said to be looking into medicines that can prevent or reduce hearing loss.

While it may be too late to help some baby boomers who are already experiencing the effects of hearing loss, younger generations that are growing up on iPods may prove to be a huge market for that kind of medical attention, perhaps sooner in their lives than boomers. A Tel Aviv University study in 2011 concluded that current teens are damaging their hearing from use of personal music players and these effects may start showing up when they enter their 30s and 40s.

A drug that effectively addressed hearing loss might be highly profitable. But part of the problem in bringing such a drug to market is testing it on people. Prototype drugs have prevented noise-induced hearing loss in laboratory animals, but it has been hard to know whether the same protection is possible in humans. How, then, to test it on people?

Temporary hearing loss

PhotoColleen Le Prell, a researcher at the University of Florida (UF), says she has the answer. Le Prell devised a way to cause temporary hearing loss in a group of volunteers. She uses controlled music levels that accomplished that and met national safety standards for research on humans.

"Dr. Le Prell started with a unique idea to create a reversible noise-induced hearing loss and has established solid groundwork for this new model in the use of clinical drug testing," said hearing expert Jianxin Bao, Ph.D., an associate professor of otolaryngology and biology and biomedical sciences at Washington University School of Medicine in St. Louis, who was not involved in the UF study. "As for every new model, several unknown factors exist for this elegant experiment model, which requires further detailed studies."

The objective, of course, is to speed up the time in which trials can be conducted. The sooner a drug for hearing loss can get FDA approval, the sooner people at risk for hearing loss can receive treatment.

Drug needed

"There's a real need for drug solutions to hearing loss," Le Prell said. "Right now the only options for protecting against noise-induced hearing loss are to turn down what you're listening to, walk away from it or wear ear plugs, and those options may not be practical for everyone, particularly for those in the military who need to be able to hear threats."

About 26 million American adults have noise-induced hearing loss, according to the National Institute on Deafness and Other Communication Disorders. The group says prevention is key because damage to hearing-related hair cells in the inner ear by loud noise is irreversible.

Though hearing aids can help amplify sound and implanted devices can restore some sensation of sound for those with more profound hearing loss, they do not restore normal hearing. The goal of pharmaceutical researchers currently developing drugs is to prevent hearing damage in the first place.

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