For this week's concerts, the National Symphony Orchestra's guest conductor has put two unusual reguirements in his contract: a "small helium tank" (one with enough helium to fill six 8-inch balloons per formance) and "access to the ceiling space over the audience."

Spokesmen for the NSO are not quite sure of the reason for these requests, but there may be an ominous hint in one of the items listed on the program: The "Hindenberg" Concerto (S. LZ-129) of P.D.Q. Bach.

The conductor for this occasion will be the world's leading authority on "history's most justly neglected composer": Peter Schickele, the discoverer -- in fact, the inventor -- of Johann Sebastian Bach's youngest and most feckless son. Besides the "Hindenberg" Concerto, Schickele will conduct the "Desecration of the House" Overture (S. 10-9-8-7-6-5-4-3-2-1). He will use his unique baritone to sing (if that is the word) the barking solo in his (or rather P.D.Q. Bach's) canine cantata, "Wachet arf," and will be the bassoon soloist in the Concerto for bassoon vs. orchestra (S. 8').

The bassoon, traditionally and significantly the clown of the symphony orchestra, is Schickele's instrument. At one time, he recalls not without pride, he was the only bassoonist in Fargo, N.D. Now, as far as anyone has been able to determine, he is the only faculty member at something he calls the University of Southern North Dakota at Hoople -- a long commute from the home in Brooklyn that he shares with his wife and two children.

When Schickele is too busy barking and bassooning in this week's concerts, Andrew Litton will conduct. There will be no conductor in the "Echo" Sonata for two unfriendly groups of instruments (S. 999999999). "A conductor would only get caught in the crossfire," a spokesman for the orchestra explained.

Schickele knows about getting caught in crossfires. He has lived 20 of his 48 years in a crossfire between his own serious work and the outrageous effusions of his "discovery."

"A lot of people don't know that I do anything serious," he says. "They expect everything to be funSee SCHICKELE, F4, Col. 4 ny, and I get treated like the clown who wants to play Hamlet."

He is a bear of a man with a bushy, graying beard that he grew some years ago -- possibly because critics were beginning to notice similarities between his photos and portraits of P.D.Q. Bach. When conducting the music of his alter ego, he wears a white tie and tails that look like they have not been cleaned and pressed since the 18th century. He tries to limit himself to 40 or 50 P.D.Q. Bach programs per year. The National Symphony tried to get him for more than two concerts on the current visit. At last report, only seats with a restricted view were still available (at least they should let people see what will be going on up near the ceiling), but standing-room tickets will go on sale a half-hour before the performances on Thursday and Friday nights.

In spite of his feverish activity as a pseudonymous composer, Schickele has composed as many serious pieces, published under his own name, as he has "discovered" works by his alter ego. "I have about 70 works published now," he says. "That's quite a respectable oeuvre." His two most recent serious works are a Concerto for bluegrass band and orchestra that had its world premiere last month in Baltimore and "American Dreams," a string quartet that was performed last year in the Terrace Theater. He is also working on a piece for chorus and jazz band.

The world premiere of "American Dreams" was given in New York April 1. "The timing couldn't have been worse," Schickele says. "Everyone was waiting for the other shoe to drop."

About a dozen of his serious works have been recorded, and they "seem to make their way to the people who are interested," he says. "On records, you don't get people coming in the way they do in the concert hall and waiting for something to laugh at. I have had some nice feedback. I remember once in a New York record store, I was browsing through some records and a clerk came up and asked me if I was Peter Schickele. I confessed that I was and got ready for some questions about P.D.Q. Bach, but he said, 'I love your elegies for clarinet and piano; I play it every day.' Something like that can really make your day."

P.D.Q. Bach may have been born in 1742 (there is conflicting evidence), but he was not conceived until 1965. Before then, and even after, pop and folk music helped Schickele earn a living -- as an arranger for such singers as Joan Baez, Buffy Sainte-Marie and Paul Simon. Today, he does not hesitate to use pop and folk elements, along with strict classical forms, in his serious music. "American Dreams" includes elements of jazz, Appalachian songs and fiddle tunes, a fox trot, a Navajo song and even a seven-note melody he learned from a bird outside his summer home in the Catskills.

Long before the idea of P.D.Q. Bach was born, the seeds were planted here in Washington when Schickele (born in Ames, Iowa) was growing up in the 1940s. With some of his friends he formed a band, Jerky Jim and his Balmy Brother, that used to practice in the basement of his home in Friendship Heights. Their specialty was imitations of Spike Jones and his City Slickers, but "even then," he says, "we did a lot of serious arrangements of folk music."

The sense of humor that makes P.D.Q. Bach a smash hit at the box office can also be heard in some of Schickele's serious work, but the process is reversed. In the role of P.D.Q. Bach, he makes light of things that are usually taken seriously; as Peter Schickele, he explores the serious dimensions of things that are usually taken lightly. In either case, he provides an element that has been heard too seldom in the serious music of our time.

"Most contemporary music is forbidding," he says, "and I'm a friendly sort of guy. I don't like ramming it down people's throats. For my taste, contemporary music has gotten too far away from folk music."

His own ideal as a composer is probably Mozart. "He is far and away the biggest part of my record collection," Schickele says. "What makes him very special to me is his combination of wit and sentiment -- also his kinetic energy. I'm not a good dancer, but I love music that makes me want to dance. The whole post-Webern movement lost that completely. Now, Philip Glass is picking up the momentum that was lost in the European avant-garde tradition. I think one of the great problems in contemporary music is how little fast music there is. Our masterpieces are things like Crumb's 'Ancient Voices of Children' -- slow, atmospheric things."

While most of his income is derived from the P.D.Q. Bach music, Schickele finds more and more musicians interested in commissioning his works. What usually happens is that a group (ranging from the McLain Family Band to the Audubon String Quartet and Calliope, a Renaissance band) hears some of his music and wants more of the same. The most spectacular commission so far, however, is in the P.D.Q. Bach vein: "The Abduction of Figaro," a "very grand opera" that had its premiere last year in Minneapolis.

"I think the two sides of my work are coming together," Schickele says, "in the sense that there are some things in the Schickele music that sound P.D.Q. Bachish. I like both sides of the coin so much that I try to have my cake and eat it, too -- and it seems to be working. There is no conflict in my mind between the two kinds of music. I can work on both almost simultaneously. If there is any conflict, it is in other people's minds."