After an hour of listening to the tubas in an exhibition room at the University of Maryland, it isn't hard to imagine the most torture-resistant human bolting for the door screaming, "I'll talk, I'll talk!"

Dozens of tubists gathered for the International Tuba-Euphonium Conference tested the handiwork of the world's premier tuba manufacturers at the university's Center for Adult Education, where the five-day tuba fest is being held.

Cradling horns that look like exotic plumbing fixtures and sell for as much as $9,000, they ran through arpeggios, negotiated treble flourishes and played gong-like bass notes that vibrated ceiling tiles. The overall effect was like the sound track of an Anacin commercial.

"If only they'd play something, instead of just blowing notes," said Officer R. Spruill, a campus police officer assigned to guard the roomful of tubas. "It's starting to get on my nerves."

It was easy for Selmer Co. representative Lloyd J. Fillio to say, "This is not so bad." His ears were plugged with cotton.

"I learned my lesson long ago," Fillio said. "You stand here all day and the continual bombardment of sound just wears you out."

Fortunately, all is not cacophony. When the time comes to make sweet tuba music, nobody can do it better than the two dozen world-class tubists who have gathered for the conference with almost 300 other tuba players for concerts, workshops, competitions and world premieres. The crowning spectacle will be a gala concert Friday on the steps of the U.S. Capitol in which more than 200 tubas will play a composition called "Deep Potomac Bells," written to commemorate the 350th anniversary of the founding of Maryland.

Among the tuba luminaries participating are James Self, who played the mother ship's tuba-reply in the musical dialogue in the movie "Close Encounters of the Third Kind." Also, Harvey Phillips, a man of tuba-like bulk and energy who was once the subject of a New Yorker profile, and Rich Matteson, whom Phillips was quoted as calling the greatest jazz tubist alive. They all share enormous lung capacities, what Matteson describes as "lips strong enough to do push-ups with," and an abiding love of the brass instruments whose reputations have suffered over the years.

The conference is sponsored by the university's Summer Institute for the Creative and Performing Arts, along with the Tubists Universal Brotherhood Association, (TUBA, of course).

"You remember Cannon, the fat TV detective," said Matteson, explaining the indignities to which the tuba has been subjected. "Every time he came on, the theme music was played by a tuba."

Tubas are nearly as ubiquitous as honeysuckle now at College Park. There's a "tuba office," the conference program comes in the shape of a tuba and tuba music wafts over the breezes and throbs down the hallways where tuba T-shirts are on sale, and bumper stickers say "Tuba-playing is a low blow."

And in the exhibition room, where dozens are exhaling into tubas to their hearts' delight, Miratone representative Jim Gavigan enjoys the racket, knowing he will sell 30 to 40 tubas as a result of the conference. His only worries are that the players don't drop the 24-pound Kaiser tuba, his biggest model, and remember to wipe the mouthpieces after trying the horns.

Otherwise, "This may be the biggest center for herpes in Maryland this year," he said.