If an elderly parent has trouble hearing, don't shout.

"To shout at anyone with a hearing problem, particularly the elderly, is self-defeating," says Dr. Walter A. Petryshyn, medical director of the Deafness Research Foundation."The most important factor is not to lose your patience," he says, "but to determine whether they need professional help to hear or whether they are just tuning you out - something the elderly may do.

"Also, shouting places the elderly in an uncomfortable social situation. They feel confused and upset about the condition. And the problem may not be a hearing loss, but some other problem."

There are 7 million Americans suffering from presbycusis, a hearing loss in the aging - and the number is increasing as lifespans extend, according to the foundation, a non-profit group dedicated to research on hearing disabilities.

The most significant deterioration in the elderly occurs in the cochlea, the nerve part of the inner ear, in the high frequency sounds, which are vital for the discrimination of words in hearing.

"The problem can be hereditary, but other factors may be involved," Petryshyn says. "Unfortunately, there is no surgical cure, and there's no medication that can alleviate or cure the problem."

If a medical examination discloses a significant nerve loss in high frequencies, rehabilitation is required. A hearing aid may help.

"The only help now available is the hearing aid, which amplifies all sound," Petryshyn says.