Speaking volumes.

Parents often say to their children it's not what you say, but how you say it. Public-speaking experts and corporate executives echo this advice. They agree that effective communication, whether in the boardroom or the lunchroom--plays an integral role in how fast, or how slow, you move along the corporate fast track.

Mannie Jackson, senior vice president of development and customer alliance at Honeywell Inc., a Minneapolis-based manufacturer of home and building controls and aviation systems, knows this well. "One of the major signs of assertiveness and leadership is public speaking," says Jackson, who makes at least four presentations a week at customer conferences, universities and the office. "It enables you to be recognized [in your industry.]" Jackson is definitely a recognizable figure at Honeywell. The 20-year company veteran is responsible for Honeywell's worldwide distribution of control products and has a $180 million operating budget.

James Williams, an NAACP spokesman and a speech writer, says that an effective speaker always leaves his audience with "something to walk away with." Williams offers the following tips on how to captivate an audience.

* Make sure you write a speech that has a beginning, middle and end.

* Read to gain knowledge in a variety of areas.

* Understand your audience and its interests.

Marilynn Davis, senior director of American Express Bank Ltd. in New York, says that she often uses visual aids during her presentations. "People like to look at things," says Davis. "You need to be able to offer a snapshot of what your point of discussion is."

To some, public speaking comes naturally. But to others, the thought of addressing an audience results in sweaty palms, a dry throat and a severe battle of nerves. Experts have found that a correlation definitely exists between those who get ahead and their willingness to make themselves heard.

"Public speaking is a learned skill," says Terrence J. McCann, executive director of Toastmasters International, a Calif.-based public-speaking organization. "It's like learning to write, play baseball or volleyball. It's simple, but complex."

Toastmasters, which has 7,600 clubs in 50 countries, provides members with audio tapes of such well-known public speakers as the Rev. Dr. Martin Luther King Jr., as an exercise in effective use of voice, style and organization, says McCann.

For more information on public speaking, consult the following sources:

* How to Present Like A Pro: Getting People to See Things Your Way by Lani Arredondo (McGraw Hill Inc.; New York, $12.95).

* The Executive's Guide to Winning Presentations by Herman Holtz (John Wiley & Sons Inc.; New York, $12.95 for paperback and $29.95 for cloth.)

* Toastmasters International, Terrence J. McCann, executive director, P.O. Box 9052, Mission Viejo, Ca 92690; 714-858-8255.