Nobody cheats at the J.S. Bach International Competition that begins today at the Lisner Auditorium. The judges, seated behind a screen, cannot see the contestants. The audience is strictly forbidden to communicate with either the judges or the contestants. The judges do not talk to one another; they simply give marks to each contestant. Everybody plays the same repertoire -- this year Bach's demanding pieces for unaccompanied violin or cello.

There is even a runner on the stage so the judges can't hear the footsteps of the contestants; some judges might prefer not to give prizes to women.

The woman who presides over this scene is Raissa Tselentis, whose first name has "queen" as its root meaning. She has little face-to-face contact with the contestants -- "I don't know their names. I don't know who they are," she says. Most of her communication with them has been by mail.

"I had a dream of creating a competition around Bach, one about which people would say there is no favoritism," she says.

She never chooses the three judges until after all the contestants have entered; she doesn't want students to be judged by their teachers.

The competition has an integrity worthy of the music; Tselentis feels it's "the competition by which all others are judged."

"Bach is foolproof," she says. "Anybody who comes to a Bach competition is a very intelligent musician. He doesn't go by emotional feelings and finger facility. He has a heart and a mind combined with the fingers. He knows he can make the grade."

And they usually do. In the 27 years since Tselentis has been running Bach competitions, she can think of only two people who really didn't have the musical skill to participate. That's not bad considering anyone can enter as long as he pays the $50 entrance fee, supplies a birth certificate and completes an application which asks only for basic personal data. She doesn't want to know about a contestant's past competitions and awards -- all that counts is how they do during the three days of her competition.

When she started her Bach competitions in 1958 -- usually but not always for pianists -- people questioned her choice; why not a Chopin competition? "I said, 'Chopin, there is in Poland. Liszt there is in Hungary. But Bach, there is no competition of Bach in any part of the world, international. So I decided to start one," says Tselentis.

Music has been a part of Tselentis' life since she was 5 years old on a Greek island where there were no foreign residents. Her parents started her on the violin, which she found hard to tune. One day in frustration she threw her violin on the floor, breaking it to pieces.

Then her parents let her switch to the piano, a less breakable instrument which, she says, "I loved from the beginning . . . It was my instrument. All I wanted to do was play the piano and when they wanted to punish me, they told me they would stop my piano lessons."

Why does Tselentis devote her life to giving money to pianists? Perhaps because she was once a pianist who needed money. She studied in Berlin for five years before coming to America in 1929, still in her teens and hoping for a concert career. Six days after she landed, the stock market crashed, and so did her plans. New York City in the Depression offered little work for musicians -- or at least little money. She played on a weekly radio show for a year. "They didn't pay me anything. They said, 'Darling, play for the experience.' " And she managed to rent a small studio on 57th Street where she gave piano lessons.

In the early 1950s she met and married military economist Paul Chadwell, who brought her to Washington. They make a good team: she artistic, dramatic and chatty; he more logical, less flamboyant and always there with a solution when his wife can't think of one. Although Chadwell is not a musician, he has, according to Tselentis, a "wonderful ear."

It takes Tselentis two years to put the competition together because she insists on doing everything herself -- from raising money to choosing "the thoroughbred musicians" who will serve as her judges, to preparing and sending out hundreds of letters and brochures to music schools and contestants all over the world.

The hardest thing she has to do is "collect the money" for prizes, something she finds a little humiliating. For this year's competition, she has managed to raise $30,000, which will be divided among the top three winners on each instrument. Her sponsors are loyal, and many, like David Lloyd Kreeger, have backed her since the beginning. In addition to the cash prizes, the two first-place winners receive guest appearances and a two-month trip to Germany. This year there will be two sets of winners: violinists and cellists. Everyone who enters the competition receives a certificate of achievement, even those who carry the lowest marks.

Winners of the competition go on to better things. Perhaps best known are Angela Hewitt, who recently won the prestigious Canadian Bach Competition ("our three judges picked her five years ago," Tselentis proudly declares) and Ursula Oppens. One winner, Charles Fisk, was asked to play at the Carter White House the day after the Bach competition. Another, Hans Boepple, was a music student at Indiana School of Music and was offered a faculty position there shortly after he was pronounced a winner.

"In the Bach competition there are no losers. Just to enter with that music, just to memorize it, you got to be somebody," says Tselentis.