Research holds hope for people who lose hearing through noise exposure

By Amy Wimmer Schwarb • Published: April 3rd, 2013
Category: Health in a Heartbeat

When it comes to protecting your hearing, you should follow the rule of “toos”: Be careful to avoid noises that are “too” loud, “too” close or “too” long.

Noise can become dangerous when its duration, frequency or intensity is too extreme. Those types of sounds — the constant whir of power equipment in a woodworking shop, for instance, or the sudden, acute blast of a nearby explosion — can cause noise-induced hearing loss.

But a recent lab breakthrough has brought scientists closer to reversing the type of hearing loss caused by exposure to noise that is just too much.

Noise can damage sound-sensing hair cells in the inner ears. These hair cells cannot regenerate themselves in humans — or in any mammal. But birds and fish can create new sound-sensing hair cells as needed, and scientists have been searching for years for a way to bring humans that same capability.

The theory goes that hearing will improve when newly generated hair cells replace the ones damaged by loud noises.

The Harvard Medical School team that took on this challenge recently has answered that question: Yes, the mammals used in this experiment did regenerate hair cells in the inner ear. And, yes, those new sound-sensing cells also helped them recover some of their lost hearing.

The researchers gave lab mice with noise-induced deafness a drug that blocked a cellular pathway in the inner ear. When the mice received the drug, the pathway was blocked — and different types of cells near the ear’s cochlea, called surrounding cells, transformed themselves into hair cells.

And with that, the mice recovered some of their hearing.

Scientists hope further research will provide a bonafide method for reversing deafness in some of the 250 million people around the world who have suffered hearing loss. And that’s an outcome worth making some noise about.