When zoologist Doug Gill talks about warts and carbuncles he's not referring to his specialty, frogs. He's sweating bullets over the annual horror of reauditioning for the Choral Arts Society.

"The fright," says Gill, "is that all your warts and carbuncles and musical wretchedness will be exposed. You're as naked as you could possibly be, and there's no hiding anything."

It's a trauma that humbles many confident professionals. Knight Kiplinger, editor in chief of Changing Times magazine, has been singing with the Oratorio Society for more than a decade. But each year, as he heads out for his audition, he looks as if he's "going off to take the college boards."

Herein lies a paradox. Annual bouts of anxiety, it seems, are a small price to pay for the therapy of singing in a chorus. "It's not light relaxation. It's very intense," says Kiplinger, "yet the intensity is therapeutic. After an Oratorio Society rehearsal I am usually very keyed up in a pleasant way. Not sleepy, as I typically would be, but full of energy. I putter around the house, doing projects, and humming."

On Mondays the Oratorio Society sends 160 choristers off into the night, humming and revived. On Tuesday nights, it's the Choral Arts Society's turn to transform 170 wayworn souls.

The schedule, which Patricia Pickard of the Choral Arts Society describes as "very time demanding" and occasionally "exhausting," intensifies as performances approach.

"I am respectful of the fact that every single one of the people in the chorus has some other primary commitment," says Norman Scribner, director of the Choral Arts Society. "I am not running a prison camp."

Behind the recent spate of rehearsals, with the attendant humming and feeling "keyed up," lies the collaborative effort of the Choral Arts Society and the Oratorio Society to present a mini-festival of Haydn's oratorio music. Tonight at 8:30 in the Kennedy Center Concert Hall, the Choral Arts Society performs "The Seasons." Sunday at 7:30 p.m. the Oratorio Society offers "The Creation."

"Virtually everyone leaves rehearsals enthralled. We may be tired, but there's a sense of enthrallment," says Gill, a bass. Echoing that feeling, Pickard says "you start to sing and immediately you are renewed . . . It's a real effort to get there but when you do you are totally energized."

"It's precisely because of the intensity of professional life in Washington that choral singing is such a therapy," says Kiplinger. "Washington is a cerebral city, and choral singing combines the best of the cerebral and the visceral."

Scribner sees the chorus as an opportunity to perform at a professional level without assuming the burdens and risks that attend a full-time career in music. "It's a chance to sing with the symphony, with great conductors, on the stage of the Kennedy Center, to tour . . . to imbibe the glories of an extraordinarily high level of professionalism without all the agonies."

For some, like Ken Byram, an employe with the Federal Aviation Administration and a tenor with the Oratorio Society, choral singing is a remedy for the frustrations of working in a bureaucracy.

"There's a lot of work in Washington with a fairly low level of immediate feedback . . . maybe that's one of the secrets behind the active participation," says Byram.

And the social benefits of this group therapy? "My mother thought this would be a great opportunity," says soprano Grace Burford, a professor of theology at Georgetown University. "When I mentioned that I wanted to sing, she said, 'Oh, well, maybe you'll meet somebody.' "

Choral groups may be a more wholesome environment for spouse-hunting than discos and singles bars, but those who spend unpaid hours in rehearsals and performances say the music is their primary motivation.

"People want to join because they know musically it's a great organization," says Pickard, who also works for the Choral Arts Society and says that after a particularly good concert it is deluged with calls from would-be singers wanting to audition. Burford "joined to sing and to meet people, but not to meet one person."

* In the late '70s, however, Kiplinger did meet one person: an Oratorio Society singer, Ann Miller, now his wife.

"We are not really sure when we first officially met. We were probably both in the chorus for maybe a year." After some casual chatting during breaks, he asked a man in the bass section what her name was, and the relationship progressed. "But the fact that my wife and I can't remember exactly when we met is evidence of what a serious coming together of musicians it is."