In the ad, two laughing couples, perhaps in their late 40s -- their teeth flashing, skin tanned -- crowd together on a sofa, sharing a conversation and maybe a joke or two, and clearly relishing each other's company.

"For every need and lifestyle," says a headline over the photo, the subject of which is not at all evident. What product is being pitched here as a key to living life to its fullest?

Why, hearing aids, of course.

As baby boomers enter their 40s and 50s, many more of them are encountering hearing problems stereotypically associated with old age. And an industry that has long worked with some frustration to persuade more older Americans to wear hearing aids has spotted what is logically the next big market for its products.

"We're picking up the challenge, to a greater and greater degree, of figuring out how to dialogue with boomers," said Carole Rogin, president of the Hearing Industries Association, which represents the $1 billion-a-year U.S. hearing aid business.

"All of the companies are trying to reflect the array of ages and lifestyles of people with hearing loss and certainly 78 million people moving into the segment of midlife to older Americans is an important marketing fact for companies," she said.

That interest reflects not only the number of boomers, but that more of them say their hearing isn't what it used to be.

The National Center for Health Statistics reports that 20.4 percent of people between the ages of 45 and 64 now say they have at least mild hearing loss. That figure, from a survey done in 1997, is up from about 14.8 percent in 1988.

In the past few years, President Clinton's and talk show host Rush Limbaugh's encounters with hearing loss have drawn widespread attention to the fact that such problems don't always wait for retirement.

It's not clear why more boomers are experiencing hearing loss. Some audiologists attribute it to boomers' exposure to loud music and other trappings of modern life, like snowmobiles and snowblowers. Others say the hearing of today's boomers is not any worse than past generations; they are just more demanding when it comes to health.

"I think baby boomers simply have the hearing their parents have but they have much higher expectations, and they have the complaint behaviors that is much more like their kids," said Dr. Robert Dobie of the National Institute on Deafness and Other Communications Disorders. "I think we're healthier than we used to be, but we demand more of our health."

Those demands can turn into frustration for boomers, who find hearing loss complicates work and social activities that are the focus of an active lifestyle.

The stigma is one of long standing. The industry estimates that only about 20 percent of Americans with hearing problems wear hearing aids, a figure that has barely budged for years. That may say something about the expense of hearing aids -- from $800 to $3,000 per ear, depending on the sophistication of the device -- a cost not usually covered by insurance. But it also reflects a public mindset that awards hearing aids all the cachet and sex appeal of, say, orthopedic shoes, people in the industry say.