It's called the gift of gab. And in this world of videos, audios, movies and cable TV, the business of providing live speakers is flourishing.

"The lecture business is booming to the extent that it's never boomed before," says Daniel Moore Jr., board chairman and general director of the 152-year-old International Platform Association. "It seems to be depression-proof. In the last 10 years speakers' fees have gone up 1,000 percent.

"It's the great golden age of the speaker. There's no doubt about it."

Moore says the increased visibility of celebrities through the media and the high cost of entertainment are two reasons why people are so willing to pay to hear a live speaker.

For a one-hour speech Henry Kissinger earns $18,000; Abigail Van Buren and her sister Ann Landers, $8,000 each; Art Buchwald, $10,000; Billy Martin, $15,000; Jimmy Carter, $20,000. None of the figures include expenses--also paid.

Bob Hope pulls in $40,000 for a one-hour chat, and Arkady Shevchenko, the highest-ranking Soviet official to defect to the free world, will be paid $46,000 to speak at the June Management Centre Europe Conference in Brussels.

The latest instant celebrity to jump on the lecture bandwagon is former Justice Department consultant Barbara Honegger, 35.

"I can only compare her to Midge Costanza of the Carter administration," says Don Walker, president of Harry Walker Inc., explaining why his company has made an offer to Honegger.

"Midge was very, very successful on the lecture circuit, and she said herself 'I made more money lecturing than I did in the White House.' "

It is estimated that Honegger will make $1,500 to $3,500 a speech.

Many on the lecture circuit say it's not just the high fees--but also the experience--that lures them to audiences.

"I was very much disappointed when streaking was popular on college campuses, that I never had a nude person run through one of my lectures," cracks CBS news commentator Eric Sevareid.

"I had the perfect retort all ready. I was going to say 'as unaccustomed to public streaking as I am.' "

Audiences, says Sevareid (whose first lecture was in 1940 at the Royal Institute of International Affairs, London) "vary a lot with the institution you're at. Businessmen are probably the least demanding. They run on schedules.

"You end up doing more at colleges, especially the small ones, because they don't get that many famous people coming to the campus. You end up teaching classes and being on the campus radio station . . . that doesn't bother me."

But before you pick up that phone to tell your employer you're switching to a more lucrative profession, it's important to know that getting started on the lecture circuit is not easy.

"To be successful you have to have to have three things: 1) recognition, 2) knowledge and 3) you need the ability to communicate what you know," says Bernard Swain, executive vice president of the Washington Speakers Bureau.

Swain says his company gets about 40 letters a day from people who want to speak publicly. "Out of 200 letters a week we only accept about two people to book."

Washington is one of the best markets of potential speakers, and booking agents know it. Accordingly, five of the 10 largest lecture bureaus in the U.S. are Washington-based; three are the fastest growing lecture agencies in the country (see sidebar).

Experts advise that whether potential speakers are politicians, nuclear arms experts or diplomats, they should swallow their pride and speak for free to get practice and exposure.

That advice, however, doesn't always hold true.

For example, when several former Iranian hostages who had never spoken before an audience were suddenly in demand on the speakers circuit--at $1,500 to $3,000 an appearance--there was no need, nor time, for free practice talks.

If you're a celebrity, says Joe Cosby, executive vice president of Conference Speakers International, a Washington-based firm, you can get by with a less-than-eloquent speaking style.

"I know of a major news commentator who was very well known, but not that great of a speaker. We advised him, as gently as possible to not offend him, that maybe he should speak for 10 to 15 minutes and open the rest of the program up to questions and answers. He was great at the Q and A format."

In other cases, companies may spend months preparing their clients for the lecture circuit with the latest audio and video equipment. Occasionally comedy writers are consulted.

One such writer is Gene Perret, who has been writing jokes for Bob Hope since 1969 and is working on a book tentatively called "Humor for Speakers." He believes that comedy, where appropriate, can liven up a speech faster than any other tool.

"I think anyone can be funny. The trick is to relax with the audience, pretend you're with your friends.

"Humor enhances the speech because it makes the person likable. People will remember it better because humor deals more with images than in abstract thoughts."

Perret says even a speech on a serious topic can use a humorous interlude to relieve the audience from digesting facts.

Once a client is booked, most agencies charge 15 to 30 percent of the lecture fee. However, if a client signs with a firm that manages as well as books, there is often an initial evaluation fee ($200 and up).

The main markets for speakers are colleges and universities, companies and associations, conventions, local clubs and town halls.

Diversity in speakers and topics--like speakers' fees--has also grown enormously in the last 10 years.

Exiled King Rechad Al-Mahdi, 36--who fled Tunisia a year after being crowned in 1957 and is now a London stockbroker--is one of the latest rookies on the lecture circuit, being billed as the only king willing to speak to U.S. audiences. His manager hopes that unique quality--even though he was exiled at age 11--will draw fees between $1,000 to $5,000 per lecture.

According to Melanie Bonfiglioli of the American Program Bureau, 10 years ago people wanted to hear rebels and social activists.

Now audiences want to hear from a wide assortment of speakers, she says. "Except for black audiences. They still want to hear social activists. Our black speakers are booked every day through Black History Month. They bring in a lot of money year round. They're very much in demand."

Business experts, politicians, authors, movie stars and futurists--the fastest growing category--are also sought after in the 1980s.

In a business that annually creates "literally hundreds of millions of dollars in profits," according to Moore, it's not surprising that lecture agencies are fiercely competitive.

Ken Eisentein, president of the American Program Bureau--the only publicly owned company of the 10 largest lecture agencies--says his company booked about $6 million in lectures last year and figures have increased 15 to 20 percent every year since 1977.

Last year alone an estimated $2 to $6 million in speaker's fees were booked by each of the 10 largest lecture firms. And already 1983 bookings are surpassing last year's totals.

Maybe it should be called the gold of gab. CAPTION: Picture 1, Billy Martin: $15,000. AP; Picture 2, Ann Landers and Abigail Van Buren: $8,000 each. AP; Picture 3, Bob Hope: $40,000