Around 5% of all people over the age of 50 have what is called golden ears. This means that they can hear the full range of frequencies detectable by the human ear (roughly 20 hertz to 20 kilohertz). Most people lose some of their hearing with age. Now the reason for golden ears is being studied.

American researchers at the University of Rochester have studied the hearing of mice as they grow older. For a while now they have studied a mouse line known as CBA, which gradually loses its ability to hear high frequency sounds as it ages, just like in humans.

The CBA mice do however not breed very well, so the lead researcher, Frisina, decided to cross them with a more virile strain known as C57 Black 6. The C57 mice are known for their poor hearing but, much to Frisina's surprise, the resulting offspring not only bred better than the original CBA line, they also retained exceptional hearing into old age.

He believes that the mice from his new mouse line are the rodent equivalents of golden ear humans and he has the experimental results to back him up.

In the brain rather than the ear

In this way the scientists have inadvertently created an animal model for studying the age-related hearing problems that occur in the brain rather than the ear.

Frisina would now like to identify the genetic factors responsible for the golden ear phenomenon. A better understanding of how age-related changes in the brain stem and cortex contribute to hearing loss could lead to more effective hearing devices or even pharmaceutical treatments.

Source: www.scientificamerican.com