With Tanglewood Festival Chorus, their harmony lasts 35 years

On a recent evening, about 115 people are gathered in an airless room in the basement of the Cohen Wing of Symphony Hall.

''I've heard a lot of great singers," says conductor John Oliver, addressing the Tanglewood Festival Chorus, assembled for a rehearsal of Beethoven's ''Missa Solemnis." ''But I've never heard anyone greater than Rene Pape, who will be joining us as the bass soloist next week."

Turning to the bass section of the chorus, he adds, ''You've got to match him here." The singers laugh. ''Start smoking now," Oliver jokes, in an environment full of no-smoking signs.

Beethoven's mighty mass, which the chorus will sing with Pape and the Boston Symphony Orchestra under music director James Levine Thursday through Saturday, is one of the most difficult works in the choral repertory. These singers will be performing all two hours of it from memory. But they take it in stride, and they're doing it on only nine rehearsals, including a read-through last fall. This wouldn't be possible if the group had not repeatedly performed the work since 1971, most recently five years ago with former music director Seiji Ozawa.

So it is probably more accurate to say that rehearsals for this week's performances began 34 seasons ago, when the chorus was just a year old and sang the work for the first time. Three of the founding members of the group are still active in it -- alto Maisy Bennett, 80, soprano Joan Sherman, 70, and bass Steve Owades, 55 -- along with Oliver, 66, the founding conductor.

The four musicians arrive before rehearsal starts to reminisce about their 35 years together.

In 1968 and 1969, Oliver, then conductor of the Framingham Choral Society, became assistant to BSO music director Erich Leinsdorf for vocal and choral activities. In 1970, he was asked to create a permanent chorus for the BSO, which, until that time, had rotated among established local choruses and student groups from Harvard and New England Conservatory.

The new Tanglewood Festival Chorus made its debut in Beethoven's Ninth Symphony under Leonard Bernstein in April 1970. Oliver chose the ensemble's name: ''I wanted something that would distinguish us, not just 'Boston Symphony Orchestra & Chorus,' " he says with a smile.

Recalling Bernstein and that first performance, Oliver says, ''Lenny could be intimidating personally, but professionally he was easy to work with. It was all about the detail and what it meant, and as he explained how the piece worked and what he wanted, he smoked like a chimney. The next piece we did was Mahler's 'Resurrection' Symphony, and wecouldn't sing the opening choral entry soft enough for him. He let me work on it about 20 minutes, and when he heard what he wanted, he said, 'I'll buy that,' and left."

Bennett and Sherman had sung with Oliver in Framingham. Bennett was raising a family back then, and today her life is full of gardening, tennis, and volunteer work as well as music. Sherman also raised a family and still works as an accountant. The two women commute together from the western suburbs; Bennett lives in Wayland, Sherman in Sudbury. Owades, who lives in Cambridge, was a student at MIT 35 years ago; he now has a small typesetting business and also engineers concert recordings. Members of the chorus come from many walks of life, and some commute substantial distances -- from New Hampshire, Rhode Island, and the Berkshires -- to rehearse and perform.

The group began memorizing most of the music in 1980, when Ozawa led a semistaged concert performance of Puccini's ''Tosca" at Tanglewood. ''That was our first 'lights out' event," Oliver says. ''After that, it was a slow transition. We did it first for some of the other operas, and then it was a logical step to Beethoven's Ninth. Now 95 percent of what we do is memorized."

''I like singing from memory," Sherman says. ''It means I really know the piece . . . not only my own part but the alto and tenor and bass parts, and when I'm standing behind the French horns, I know their parts, too."

Says Owades: ''I find that after so many years of rehearsal and performance, most of the major choral works are there for life. I don't even have to open the book during rehearsal."

All three singers remember favorite performances and conductors: Elgar's ''The Dream of Gerontius" and the premiere of Tippett's ''The Mask of Time" with Colin Davis; Tchaikovsky's ''Pique Dame" and Britten's ''Peter Grimes" under Ozawa; and Ozawa's last performances of Bach's B-Minor Mass. They speak enthusiastically of their world premieres, such as the Tippett, and John Harbison's ''Requiem."

Levine, the new music director, is also a favorite, although the singers say they find others more reassuring and wish that he would look at them and signal them more often. Still, all agree with Oliver when he praises Levine's ''warm, enabling personality."

They also agree the present chorus is the product of a long process of growth. ''I remember," Owades says, ''when we had to sweat like crazy to get the a cappella section of Ravel's 'Daphnis et Chloe' in tune. Now, we sail right through it."

The other singers file in to take their seats, and rehearsal begins exactly at 7 p.m. without a word being said. Oliver lifts his baton, pianist Frank Corliss plunges into the orchestral part, and the chorus launches into Beethoven's ''Credo." Soon, they're singing the huge fugue that concludes it at breakneck speed and with breathtaking accuracy, even though the sopranos are at the very top of their range. ''If Maestro Levine's recording is to be believed," Oliver says, ''he takes it even faster than that."

During a break in the rehearsal, Bennett comes up to add a point. ''We didn't say anything about the camaraderie," she says. ''I lost my husband not long ago, and the music and the chorus have been a safety net."

Says Oliver, ''It's just fun to come here and work with these people."