It was called a master class. But master singer Sarah Vaughan spent more time talking about mastering the music business than analyzing musical styles.

It was the morning after a splendid performance Wednesday night opening the four-day Wolf Trap International Jazz Festival. And Vaughn was spending about 75 minutes yesterday, at the Madiera School in Greenway, Va., listening and talking to seven young, eager singers who wish to emulate her.

They came from all over the Washington area. Among the singers were a student, two teachers, a food service worker and a sales person. None of them had to be coaxed on stage, either.

But Vaughan, who got her start by winning an amateur contest at the Apollo Theater in 1939, wasn't particularly penetrating in her comments at her first master class.

Frankly, she bent over backwards being kind to everyone.

"You were very nice," she said to Joyce Stovall, who had a cold and sang the torch song "All of Me" without much feeling. "You inspired the piano player."

To Kehembe Eichelberger, who delivered a soothing "I Wish You Love," Vaughan said: "That was marvelous. Have you studied dramatics?"

Vaughan called "The Divine One" in album titles for her elegant vocal style, reserved her most specific -- and personal -- comments for questions about the music business after the performances.

Asked how to get a recording contract, Vaughan, who's been ignored by record firms regularly, quickly shot back: "Me and record companies don't get along at all. I'd advise you to get someone to help you. But if you give them [the companies] a demonstration record, you may never know what's going to happen to it. There's so many thieves and crooks in the business."

She was also asked if there were any trends in jazz and pop music that alarm her. "Yes," she said without hesitation. "People with no talent who make a million dollars."

It didn't matter to most singers that otherwise she wasn't being analytical or pointed. "You're cute up there," she told singer Esther Williams. "You should shake your booty a little. You have a nice booty. Shake it a little."

Finally, a member of the audience, a non-singer, asked for more critical opinion.

"This is just like a job," answered Vaughan, who donated her services free of charge to the Wolf Trap Foundation. "Musicians do clinics and get as much money as they do for playing in a club."

However, she showed special attention for one or two performers. When 15-year-old David Crawford of Reston sang a deep-throated "Body and Soul," in a stiff posture, she burst into applause and said, "You remind me of when I first started singing. You should do a little more moving. But stay scared. I still am. If you get too sure of yourself, you're in trouble."

She also clearly liked Abdul Hakeem, who sang in a sweet, high-pitched voice reminiscent of Sam Cooke. "That was excellent. You have a true voice -- no falsetto. I'm going to turn on my radio one of these days and he's going to have a No. 1 hit. I hate these young boys!"

When the class ended, she signed autograpsh in a flurry -- and then rushed toward a limousine waiting to take her to an airport.

Did she like the master class experience enough to try another?

"Musicians like money," she said. "I do clinics."