This is the sorrow and grandeur of being Karlheinz Stockhausen: You write the world's only string quartet meant to be played in four separate helicopters, and yet, as helicopter quartets go, yours isn't among the best.

Stockhausen, the great German modernist, has lived his long and manic life this way, producing works that are both trailblazing and peculiar, yet somehow tainted with kitsch and pomposity. They are unique, yet rarely much better than that.

The "Helikopter-Quartett"--just released on CD--is just as it sounds. It's a string quartet written to be performed with each of the four players hovering above the concert hall in a separate helicopter. A "click track" helps keep them together, and their individual parts, plus the ambient noise of the helicopters, is beamed down to the concert hall, where it is reassembled by sound engineers. In an ideal performance, the actual whir of the helicopters above the concert hall would be just barely audible, blending into the electronically received individual parts. It has not had many performances, ideal or otherwise.

The "Helikopter-Quartett" is no joke. It was conceived in 1992-93 and first performed at the Holland Festival in Amsterdam in April 1995. The new studio recording--whatever that means, given that the original concept precludes a studio--has been released by the ever-adventurous Arditti Quartet, on the Montaigne Auvidis label.

An English critic has written that this might be the party disc of the year, which says more about the English definition of "party" than it does about the recording. William Shatner singing "The Candy Man" is a party disc; Florence Foster Jenkins singing Mozart is a party disc; Samuel Ramey singing Broadway is a party disc.

This is not a party disc. It is a very serious disc, a brows-furrowed, lips-pursed disc. When you put it in the CD player, there is at first silence, followed by the distinctive slow crescendo of the turning rotors. The four string players slowly join in, mimicking the crescendo and rising pitch of the blades, blending into the mechanical rhythm. At one point, the instrumentalists start counting out loud, for no particularly good reason. Sometimes a cornflake looks like Elvis and it's a hoot; sometimes the cornflake just looks like Elvis. This is just a quartet for four helicopters. To understand the grim sobriety of it all, one has to do a little genealogy.

Stockhausen is the preeminent German composer of the past half-century, the experimental provocateur who helped refashion the European music scene after the Second World War into a battleground of the aggressively new. With Pierre Boulez, his goal was to rethink everything about music--tonality, rhythm, sonority--and to rethink it not just theoretically, but at every turn with every new composition.

Unlike Boulez, who was methodical and mathematical almost to the point of paralysis, Stockhausen was endlessly, facilely fertile as a creator. He absorbed the ferment around him in the 1950s and '60s, and kept forging onward, producing a large catalogue of music and writings, almost all of it now published by his own company. Stockhausen was a sponge, appropriating, for example, the best of what America's enfant terrible of experimental music, John Cage, had to offer. He then out-Caged him, exploring Cage's chance and "controlled chance" procedures with even greater rigor and insight. Stockhausen even eclipsed Boulez, and reigned for years as perhaps the most frightfully audacious musical mind of his time. For more than two decades, Stockhausen has been at work on what may be the most ambitious, most self-aggrandizing, most Wagnerian project of 20th- (and now 21st-) century music: "Licht," a vast allegorical cycle of seven operas that is either an exploration of the big themes of good and evil, life and death, creativity and destruction, or perhaps just a very long meditation on the childhood of Karlheinz. (It was a horrific Second World War childhood; there's plenty of material.)

Stockhausen is a uniquely European phenomenon: an artistic idealist and megalomaniac genius with access to money and respectability. Enough money to be dangerous. Unlike many experimental composers in America, Stockhausen in Germany had the cultural resources to put his very grand schemes into action. The operas of "Licht," each named for a day of the week, have been produced as the composer has finished them. Even today, when the world would seem to have passed him by, when Stockhausen conceives of something as outlandish as a quartet for helicopters, he can find the backers to make it fly. He is, in some ways, the musical Christo, exploring wild ideas that stretch the usual concepts of musical time and space to the limits; and yet, like Christo's art, there's often an eerie sense of dreamlike beauty in his music.

The "Helikopter-Quartett" has significant historical precedents. In Venice, in the 16th century, the composer Giovanni Gabrieli explored spatial effects, arranging multiple choirs and instrumental groups throughout the vast space of St. Mark's Cathedral. In the 18th century, Haydn's Symphony No. 45 ("Farewell") ended with the musicians departing the stage one by one, the music thinning with each loss into silence. Playing with location and the boundaries of the concert hall has been an ongoing concern not just with Stockhausen, but throughout the history of music.

Like most things Stockhausen creates, the "Helikopter-Quartett" seems, at first, fashioned from equal parts sheer absurdity and intellectual gravitas. If any other composer had created it, one would be tempted to see it as a work of parody and insinuation: a wry comment on the way many string quartets play today, each musician isolated from the others, connected more mechanically than musically, producing art in the antiseptic safety of his own personal, airborne SUV. Or perhaps it is a meditation on power and control. The first performance, ultimately canceled for logistical reasons, was intended for the 1994 Salzburg Festival. The festival had planned to use Austrian army helicopters, a symbolically rich stew of music and militarism in a country that has been a leader in both fields.

But these interpretations would limit the work to a purely intellectual exercise, and Stockhausen is not about that. Nor is he a musical dadaist. Musical dada comes in many forms, from Poulenc's opera "Les Mammeles de Tiresias," which mixes an absurdist story line with a whiplash pastiche of popular music, to the musical fantasies of La Monte Young, whose "Piano Piece for David Tudor, No. 1," consists only of the following instructions: "Bring a bale of hay and a bucket of water onto the stage for the piano to eat and drink. The performer may then feed the piano or leave it to eat by itself. If the former, the piece is over after the piano has been fed. If the latter, it is over after the piano eats or decides not to."

That's dada and it's not Stockhausen. The fundamental principle of dada is to turn the question "What's art?" back at the audience. The viewer must decide why it is that when Marcel Duchamp writes "1917" on a urinal and offers it as art, one laughs and thinks about the meaning of art; and when Picasso mounts a bicycle seat on a pair of handlebars, it bypasses the intellect and sends chills down the spine. Dada is kitsch that questions art; Stockhausen's kitsch is unintentional. He offers up his art the old-fashioned way: as a serious expression of the self-sufficient, all-powerful artist as hero. His description of how he came up with the "Helikopter-Quartett" betrays an almost comic lack of self-irony:

"Early in 1991 I received a commission . . . to compose a string quartet. And then I had a dream: I heard and saw the four string players in four helicopters flying in the air and playing. At the same time I saw people on the ground seated in an audiovisual hall. . . ."

His dream isn't even translated. It is the composition, without any changes, without irony, without addition or subtraction. He dreamed of helicopters; he wrote a helicopter quartet. It takes a lot of self-confidence to turn one's dreams literally into reality. Stockhausen is the last Captain Ahab of music, and it's sad to report that at the age of 72, his new work seems just a bit ridiculous. Boulez, his onetime compatriot in revolution and often his competitor, has settled into venerable old-man status, traveling the world as a conductor and advocate of other people's music.

Stockhausen, who continues to compose, to struggle after new worlds of sound, is writing helikopter-quartetts, producing the sort of grand visions that, in America, we are too pragmatic to take seriously anymore. The saddest thing about the "Helikopter-Quartett" is that, if you remove the helicopters, the music is of minimal interest. The recording, made on terra firma with each of the players not in a helicopter, but in a different classroom of a large schoolhouse, is an oddly tame work.

The helicopter noise (presumably added in the production process) is soothing, and the music--rhythmic and imitative--is tame by most standards. The program notes, which explain at length the "staging" of the work--there's a lot of discussion and navel-gazing surrounding the performance--make the most lasting impression. Yet Stockhausen's dream stays with one. Not the particulars of the dream, which might as well have been about a piano trio performing on separate battleships, or a ballet set on an aircraft carrier. It's the mix of machine and motion and music into something strangely human and vulnerable, an old futurist fantasy of a machine more perfectly beautiful, more human, than humans themselves.

It would be nice to give thanks to Stockhausen for the chutzpah to still have this kind of dream, and make it audible. But then you remember that you can see this kind of dream any day of the week, on television, where men play polo in four-wheel-drive vehicles. Stockhausen's helicopter dream was audacious; but it's easy to find this kind of audacity in our restlessly visual, smugly surrealist commercial culture. In fact, television may do it better. These are the sorrows and grandeur of being Karlheinz Stockhausen.