FALSTAFF (who is really bass-baritone Marvin Finnley) leans on a tombstone in the half-darkness, waiting for his entry cue.

The women are sitting on a wooden bench in front of a graveyard, and Alice Ford (who is really soprano Jennifer Barron) is waiting for the corpulent knight to arrive on his amorous quest. "It's 2 already," sings Barron. It is, in fact, about 2:30 p.m., though the scene looks like midnight in a cemetery. The world's youngest and most temporary opera company is rehearsing Verdi's "Falstaff" in the scenery for H. August Marschner's "The Vampire."

This surreal scene is a master class on the preparation of an operatic role, directed by Donald Gramm, who is now one of the finest actors in opera but was not prepared for it when he began singing operatic roles about 30 years ago.

The young singers -- 24 of them, including some of the most promising in the United States -- listen closely as Gramm talks about roles he has sung: "Falstaff, Baron Ochs, Don Bartolo and Don Pasquale, they're all basically the same guy -- all old men with a thing for younger women. It's easier, now that I'm getting on in years. You couldn't have a teen-ager doing Falstaff."

The Talk is more about acting and interpretation -- getting the words and the characters and the story across the footlights -- than it is about singing. "Try speaking the lines," Gramm Tells a tenor and baritone who have been singing just a shade too sweetly, and they begin to shout at one another: "Blockhead . . . . Scoundrel." Gramm smiles approval at the heightened dramatic effect and counsels them, "Now, sing it again. Singing it, you have to be a little crude."

They are in the auditorium of the Madeira School, where "The Vampire" will have a performance at 8 p.m. on Thursday and at midnight on Saturday. The scenery for "Falstaff," which opens at Wolf Trap on Aug. 21, has been set up for rehearsals in the theater's lobby but is unoccupied for the moment.

During their 10 weeks here (two more than last year), the two dozen singers in the 1980 Wolf Trap Opera Training Program -- 10 more than last year -- are running through enough activities to wear out a cast of thousands.

Besides full-scale productions of "The Vampire" and "Falstaff," they are presenting Humperdinck's "Hansel and Gretel" and Weill's "Down in the Valley" on alternate weekends in the Children's Theater in the Woods -- two free shows each Saturday. Some of them are taking roles or acting as understudies in other opera productions at Wolf Trap, such as the "Fledermaus" that has its last performance today. Earlier, they sang in a musical salute to Richard Rodgers, and on Aug. 24 they will all sing a program called "Future Stars in Concert," a showcase matinee of favorite operatic arias. The title of this final program may sound slightly ambitious, but for many of them it is a simple, sober statement of reality.

In their spare time this summer, Wolf Trap's stars of tomorrow are engaged in an "outreach program," a barnstorming series of free performances around the Washington area, including several radio programs taped for broadcasting on WGMS. "We sang at the National 4-H Center the other day," says bass-baritone Stephen Owen. "We did everything from the quartet from 'Kismet' to the quartet from 'Rigoletto,'" says tenor Christopher King, who won the Metropolitan Opera regional audition earlier this year.

"A lot of the people in these outreach audiences have probably never been in the same room with an opera singer before," says Martin Smith, who runs the Wolf Trap program in the summer and the opera department at Juilliard in the winter, acts as a judge for the Metropolitan auditions and plays piano for some of America's leading song recitalists.

The singers in this summer's program were picked from more than 700 candidates in a nationwide series of auditions that lasted from January through March of this year. They are paid $225 per week for their work at Wolf Trap, which begins at 10 each morning with a class in body movement and continues regularly until 10 p.m., sometimes later, with other classes (acting, makeup, interpretation), individual vocal coaching and rehearsals -- not to mention public performances and master classes with such operatic experts as Donald Gramm, Beverly Sills and Anna Moffo. "After that," says one participant, "we all go home and drop dead into bed."

The hours are long, the work demanding, the pay barely above the minimum wage level and the opportunities unlimited. "For singers at our level, it's the best deal in the country," says Stephen Owen. "It's better than any other summer workshop," says soprano Ellen Lang. "Nobody does any choral stuff. In a lot of places, they invite you out for a summer training program and you find yourself singing in the chorus. It's also very pleasant -- no prima donnas, no hysterics or backstabbing. You really get the feeling that people here are rooting for one another."

Lang, who is already well-known as a mezzo in the Washington area, has recently completed a transition from mezzo to soprano and is still slightly surprised to find herself in the Wolf Trap program. "I was amazed that they picked me," she says. "I did not sing well. I still don't really know the repertoire. I asked about it, and they said there is a certain quality in my voice."

Owen was also told that he was picked despite an imperfect audition. "I sang Bartolo's aria, 'La Vendetta' from 'The Marriage of Figaro,' and afterward Martin Smith told me, 'That's a terrible aria -- we picked you in spite of it -- for your sound.'"

King, who had no trouble at all with his audition, is 24 years old -- one of the youngest in the program, which tends to pick singers between the ages of 28 and 34 -- and on the brink of starting a career. "After winning the Metropolitan audition," says King, "I was approached by quite a few management organizations who wanted to launch me -- but I decided it's too soon. I'll be singing with small companies around town until I know I'm ready all the way."

This kind of patience is amazing among tenors, who are supposed to be impetuous types, and even more amazing for King, who says he has collected "pratically every tenor recording ever made" and who "knew I wanted to be a singer when I was 11." He began singing professionally a little over two years ago and says, "I haven't stopped singing since I started." But losing the finals in the Metropolitan competition after winning the regional audition this year was a sobering experience for him. "I went up there and I sang better than ever before in my life, and I lost. For a week, I was miserable, and then I began to realize that I didn't win because I was too young. It was the first time I had even entered the competition." iWhen does he expect to see his name in lights? King smiles: "I'm only 24. Richard Tucker didn't even begin his career until he was 35. Franco Corelli didn't begin until he was 35."

Ellen Lang tends to agree, although she now feels ready to begin the big career push. "I've finally decided to get an agent," she says, "but it will have to be one to the top ones. Most people don't realize how late operatic voices mature -- we're not like ballet dancers, who have to begin studying when they are about 8 and whose careers usually go from about 21 to 31. Singers are just ready to begin a career at 31, if they want to last for a while."

Martin Smith, who serves as a mentor to the singers as well as directing the overall program, confirms this and says that for the last two years, since he has been involved with Wolf Trap, the program has been tailored for singers reaching the point of vocal maturity. "It's not really an apprenticeship program the way it was in the early years here," he says. "I wouldn't work in a program like that. We want people who are ready vocally and hungry artistically. We bring them here to give them a final professional polish, to give them exposure in good, professional productions and to help them make the contacts that are necessary to build a career.

"They work with Beverly Sills and Sarah Caldwell, both of whom are interested in hiring young singers for their opera companies. I hope that Beverly will hire a half-dozen people from this program, because they are ready -- and she knows it. The first audition she gave was to [mezzo-so-prano] Stephanie Friede, who is young but ready, and after a few minutes she had that special Beverly Sills smile on her face. She knew she was going to be dealing with important singers. Tenor Bill Eichorn covered for the role of Ottavio in her 'Don Giovanni' here, and he will audition for the New York City Opera.

"Marvin Finnely is learning the role of Falstaff here from Donald Gramm, and he will sing it in the dress rehearsal. I hope he can go right from here to singing it at the City Opera and he has already been asked to cover for one of the roles in the Washington Opera's 'Ballo in Maschers.' We are here to give young singers an opportunity at the time when they need it most, and we're very practical about it -- we introduce them to people who can give them jobs. We bring in people who do the hiring, for auditions. A lot of key people pass through here in the summer, and we make sure that they know about our singers. Many of our singers will be auditioning for the National Opera Institute on Aug. 25, the day after we close our program here."

The Wolf Trap Opera Training Program began at the same time as the performing arts park, in 1971, and it has been in operation every year except 1978, when operations had to be curtailed because of budget problems. The first staged production of Scott Joplin's "Treemonisha" was an early landmark in its history, and two alumni of that production -- Carmen Balthrop and Donnie Ray Albert -- were launched into stellar careers. Other eminent alumni include Faith Esham, who was back at Wolf Trap this summer singing Zerlina in the New York City Opera's production of "Don Giovanni," and Rockwell Blake, who now has a busy career both at the Metropolitan and in Europe.

This year's training program is costing Wolf Trap somewhere between $175,000 and $200,000, raised partly in grants from the National Endowment for the Arts and such organizations as the Packard Fund and the George Marshall Foundation.

The program, the institutional grants, the singers and their aspirations are all a part of a process that has been working slowly for the past generation and has recently begun to accelerate: the naturalization of opera in America. a

"I didn't train to be an opera singer," Donald Gramm recalls. "My teacher said, 'Why bother?' When I was beginning my career in Chicago around 1950, there was still a lot of radio work, church work and oratorios -- and it kept me very comfortable. There wasn't enough opera work around to make it worth the trouble, and it didn't pay very well. When I began to sing with the New York City Opera, they were only paying $75 per performance."

His opera debut did not begin to take off until arond 1960, and he made his debut at the Metropolitan in 1964, long after he had built an international reputation and sung with dozens of major orchestras in Handel's "Messiah" and other non-operatic works. "During my early years in Chicago, at the height of the season, I would often sing two 'Messiahs' in one day," he says.

When Gramm began, any singer with serious operatic aspirations would automatically expect to spend five or six years singing in provincial opera houses in Europe, where the art is indigenous and heavily subsidized. Now, as Martin Smith notes, "There are many American singers who build major careers without ever having to go to Europe." What has happened is the developement of an operatic substructure in America -- local and regional companies that operate something like the minor leagues in baseball, training and seasoning the performers and also building an audience at the local level.

During the past year, an avid opera-goer in Washington could have seen nearly 100 different opera productions without driving more than 50 miles. These would include visiting productions by the Vienna State Opera, the Metropolitan and the New York City Opera, but also a whirlwind of activity by local groups, beginning with the Washington Opera Company and including the Washington Civic Opera, the Opera Company of Northern Virginia, the Prince George's Civic Opera, Opera Casalinga, the Annapolis Opera and a variety of school and college productions. Gramm, who remembers the old days, says he is "astounded" at the way opera has grown in this country. Smith talks about the comparative values in America and Europe:

"I was passing through Hamburg some time ago and I decided to spend an evening at the opera. It was one of their most widely acclaimed productions, but I was terribly disappointed -- maybe it was an off night. You can go to the opera in almost any provincial city in America -- miami or Houston, for example -- and expect better singing and acting than they had in Hamburg that night."

His mention of acting is one sympton of the reason for opers's growing popularity in this country. Opera in America is now being treated as an integrated musical and dramatic experience, carefully designed to appeal to thos who will not be kept happy by beautiful singing alone. It is significant that the Wolf Trap program includes daily acting classes by Elizabeth Bishop, who formerly sang with the New York City Opera, switched to acting and now directs the opera workshop at Boston University. Also on this year's program was an intensive, five-day course on makeup by Jane Stanhope, one of the leading authorities on this art.

Young singers have come to recognize the importance of acting in opera. "I'm reading a book called 'Actors on Acting,' and it just blows my mind," says Ellen Lang. "You can substitute 'singing' for 'acting' every time it comes up. I am learning about singing from Sir John Gielgud.

"I have been learning a lot about singing from Jack Guildford in 'Fledermaus,' even though he doesn't sing a word," says Christopher King.

The soprano and tenor also learn from one another, serving as friendly critics in repertoire with which they are not yet ready to go public. "Ellen and I get out Verdi duets and kind of scream at one another." says King. "'Cosi' made us friends."

He is referring to a duet they once sang in Mozart's "Cosi fan tutti." Lang's account is somewhat more detailed: "In this duet, he was supposed to kiss me, and he sort of threw me on the floor and mashed me. So I whispered in his ear, 'Chip, this is not how people kiss,' and he whispered back, 'Shut up and sing.'"