When celebrities and CEOs speak, Diane DiResta listens. Then she trains them to speak more effectively.

Ask Vanna White of “Wheel of Fortune.” Ask Bob Lanier, the eight-time basketball All-Star and Hall of Famer. Ask any number of Fortune 500 leaders.

The Brooklyn-born Ms. DiResta aims to enhance their “executive presence.” That can translate into more money for television and radio endorsements and lectures, or help secure job promotions and lead to better relations with the press.

“Executive presence is all about communicating with authority and conciseness, conducting oneself pleasantly but productively with colleagues, the public, the media – it’s about demeanor and credibility,” the founder and president of DiResta Communications said yesterday. “It’s all about projecting a powerful image.”

But the question arises: By the time a person gets to be a CEO or a public personality such as Ms. White, wouldn’t they already have “executive presence”?

“Not necessarily,” Ms. DiResta said. “What sometimes holds back people in the corporate sector is not having the right image. A woman executive can have a nervous laugh, for example – something that could adversely affect her impact on an audience. Or someone would be ending sentences in ‘uptalk’ – with the inflection rising, almost as if that person were asking listeners for permission to end a sentence.”

Then there is what Ms. DiResta calls “wimpy words.”

“A person could be using ‘perhaps,’ ‘if,’ ‘I think,’ ‘like,’ or using everyday slang,” she said. “Or when a speaker says, ‘You guys.’ Such words simply do not work in a high-powered corporate environment. In today’s hyper competitive world, everything matters in leadership circles – personality, speech, diction, vocabulary, credibility.”

So how does Ms. DiResta coach celebrities and corporate executives, who can be known for having monumental egos? How does one tell a celebrity that, well, she isn’t delivering her speech right?

“Some celebrities can be difficult,” Ms. DiResta said. “And in some cases, their associates are afraid to tell them that they need coaching. But when those endorsements slow down, or a celebrity loses out on an important contract – that’s when the realization generally hits them.”

Ms. DiResta typically offers eight hour coaching sessions, complete with video tapings. She also offers two- or three-day corporate seminars.

She became a speech coach after earning a master’s degree in speech pathology from Columbia University and a 10-year stint with the Board of Education. Ms. DiResta also worked at Salomon Brothers as a training specialist in management development. And she was an assistant vice president at Drexel Burnham Lambert, where she recruited and trained MBAs for the institutional sales and trading training program.

“I liked my work on Wall Street, but I didn’t like the culture of Wall Street,” Ms. DiResta said. “I saw that there was great potential in becoming a speech coach, especially as corporations increasingly required their executives to make both internal presentations and public appearances.”

She found the market more than welcoming. And she wrote two books, including the best-selling “Knockout Presentations – How to Deliver Your Message With Power, Punch and Pizzazz.”

“Whether coaching sports celebrities to shine in the media, developing leaders to excel at executive presentations, or helping women to step into their power, I see my task as bringing out the best in people,” Ms. DiResta said. “I am about the power of language.

“I listen to people,” she said. “Coaching means bringing out what’s inside of you. I help people see the possibilities. I’m their sounding board. But I always listen carefully to them.”