The same fatty diets that clog arteries and promote heart disease apparently can also impair hearing, animal studies indicate, but the damage appears to be reversible, researchers reported Sunday.

While the finding in chinchillas has no direct implications for the hearing impaired, it does add to knowledge about cholesterol and suggests some damage caused by the waxy substance may not be permanent, said Dr. Tetsou Morizono, associate professor at the University of Minnesota at Minneapolis.

"It is encouraging that this effect is reversible," Morizono said. "But you shouldn't be just looking at the hearing {aspect}. You have to look at the whole health picture with regard to cholesterol."

Cholesterol, found in high concentrations in fatty foods, has been implicated in the artery-narrowing disease atherosclerosis, the buildup of waxy plaque on blood vessel walls. Recent studies indicate that 80 percent of American men have high blood cholesterol levels, which put them at risk for atherosclerosis and subsequent heart attack and stroke.

Morizono and his colleagues, presenting a paper at a national meeting of ear, nose and throat specialists in Chicago, fed high-cholesterol diets to chinchillas for six months and found the animals developed impaired hearing in the high-frequency ranges.

The chinchillas exhibited restricted blood flow to the ears, a thickening of the blood, as well as metabolic changes in the cochlea, the inner ear chamber that translates sound into electrical signals to the brain. Each of these factors could have contributed to the impairment, Morizono said.

But when the animals were returned to their normal low-fat diets, aural sensitivity returned within six months. Morizono said this seems to confirm increased hearing sensitivities reported by some heart patients put on low-fat diets.

"I think this shows that cholesterol has many, many effects in the body, and some of them are reversible," Morizono said. "But if you've got really high blood cholesterol, your hearing is the least of your problems."