JAZZ : Where Mozart Meets Monk : Prodigious pianist Keith Jarrett is as comfortable playing solo classical works as he is in a jazz trio--but don’t call him a ‘crossover artist.’

Seated at a concert grand, hands coiled over the keys, Keith Jarrett, the virtual inventor of the spontaneous, freely improvised solo piano concert, seems transformed into another arena of reality.

Head moving from side to side, body swaying, accenting each note, each cluster of harmony with a dramatic thrust, he is a study in the pure passion of music making, driven by an irrepressible internal energy that flows through his body.

“I used to tell my private students,” he says, in a phone conversation from his New Jersey home, “ ‘Play each time as though it’s the very last time you will ever play anything.’ That’s what it’s like.”

And sometimes audibly so in his performances, both live and recorded, when his spirited, ecstatically expressed vocal sounds can come close to drowning out his piano lines. Like the late classical pianist Glenn Gould, another artist who insisted upon carving a stubbornly individual path, Jarrett has frequently been criticized for the fervor of his vocal utterances.

Yet it is almost impossible to imagine how he could sustain the sheer, creative magnitude of his work, from solo piano performances and classical concerts to a long-maintained jazz trio, without the opportunity for completely free, totally spontaneous expression--including grunts, hums and moans.

Jarrett presumably will be in full voice tonight when, in his first Southland appearance in a decade, he performs with his trio at the Wiltern Theatre. The group includes bassist Gary Peacock and drummer Jack DeJohnette, who have worked with the pianist since 1983. Both associates are stars in their own right--DeJohnette with his own ‘70s and ‘80s bands New Directions and Special Edition, Peacock as a primo accompanist with Bill Evans, Paul Bley, Jimmy Giuffre and others.

Thoughtful and articulate, Jarrett’s precisely worded comments--which have been known, at times, to be communicated in acerbic fashion to listeners he felt were inattentive--are the other side of his free-flowing, stream-of-consciousness improvisations.

If his performance persona is a form of pure, physical energy channeling through music, his conversational identity can be viewed as a probing personification of logical thinking.

In a conversation that ranges freely across a discussion of his solo concerts, his new, six-CD live trio recording, his continuing interest in classical music, and his ambivalent feelings about the role of music in the pre-millennium world, he persistently declines to fall back on by-the-numbers, entertainment business generalities.

Regardless of the topic, however, one theme remains constant: Jarrett’s ceaseless desire for spontaneity, a need to work upon a blank canvas that is essential to every aspect of his diverse musical activities.

“It is the individual voice, present to itself, that needs to be heard,” Jarrett wrote in a New York Times article in 1992. “We need to hear the process of a musician working on himself.”

Jarrett, a slender, compact, bespectacled man with tightly wavy, graying hair, has for years been best-known to the wider music audience for his moody, introspective piano improvisations. For some--although definitely not for him--they signified the opening of the door to a kind of New Age jazz music that has produced such un-Jarrett-like pianists as David Lanz, Scott Cossu and George Winston.

A series of albums chronicling his solo concerts were not only highly praised, critical successes, they were best-sellers, as well. His 1975 release, “The Koln Concert” (originally on two LPs, now a single CD), has sold nearly 4 million copies, an astounding figure for any artist, but especially so for a figure so clearly associated with jazz.

While the concerts and recordings have had their share of less inspired moments, the quality level of Jarrett’s playing has been astonishingly consistent. Undefinable as either classical music or jazz, the piano solos, when they first appeared, found an immediately receptive audience.

But Jarrett now has a different view of that kind of performing, with little interest in retaining the demanding pace of the ‘70s and ‘80s.

“I always do a few [solo concerts] each year,” he says. “But I couldn’t emulate the way I did them in the past. I think I did 50-some in one year. I guess it was a kind of burnout. But a burnout of format, not of music. I have, over the years, used more and more energy per concert.”

And there is another factor. It is important to bear in mind, Jarrett points out, that “when I did 50-plus concerts in a year, my quest was simply to play a good solo concert.

“My quest now,” he says, “is a harder one; I’ll put it that way.”

The essence of the new quest in his solo programs is an effort to make each event unique and individual, an urgent desire to avoid recycling and regurgitating his own ideas.

“[This approach to the solo programs] demands more of me physically than those earlier ones did,” he explains, “and I need more time away from the format so that I can bring to it what I hope will be there. When I play a solo concert, I want everything to digest so thoroughly that it’s out of my system by the next time I play.”

The solo programs peaked in the early ‘80s. Since that time, he has concentrated largely on working with the trio and performing classical music. Much of the trio repertoire has been founded upon “standard” tunes, melodies from the great pop songwriting era of 1920-1950.

Why a return to the specificity of melody after the blank canvas of the solo improvisations--especially at a time when many jazz players had abandoned the standards repertoire in favor of originals?

For one thing, because Jarrett sees melody as emotion, always a central element in his music. But even more significantly, because of his desire to demonstrate--as with the solo concerts--that “music isn’t about material; it’s about what you bring to the material.”

Asked how he has managed to preserve the fresh feeling in his 13-year relationship with Peacock and DeJohnette, he points out that the trio has frequently had long breaks between tours and recordings.

“That’s one of the biggest reasons,” he says, noting that in the routine of one-nighters even the most gifted players can soon begin to repeat themselves.

“On a tour,” he explains, “even a brief, 10-concert tour in Japan, I can hear the music begin turning into slightly more of a version of [what it was] two nights earlier than it ever does when we play less.”

In addition to the regeneration provided by the breaks the trio members take to pursue their own projects, another element, Jarrett points out, has been vital to their association.

“We trust each other,” he says. “I trust that the next time I play with Jack and Gary, they’re going to have something to say. None of us realized what would happen when we started this. First it was new, then it was not as new. Then we recorded, and then we recorded more. If you had to write it down, it’s the same basic thing. And yet there’s nothing the same about the first recording and the last recording, except that it’s the same three people, and amazingly, we’ve retained the exact same kind of constitution.”

The most visible evidence of that “constitution” is the new ECM release, “Live at the Blue Note,” a six-CD boxed set documenting the trio’s sold-out engagement at the New York City jazz club June 3-5, 1994 ( see accompanying review , Page 74 ).

An intensely private person, Jarrett, 50, lives with his wife, Rose Ann, in a rural New Jersey farmhouse. His two sons from a previous marriage, Gabriel, 22, and Noah, 17, are both musicians. Jarrett, born in Allentown, Pa., began playing piano at the age of 3, performing at an early age in programs at Madison Square Garden and the Academy of Music in Philadelphia.

Raised and trained as a classical musician, he came to jazz in the mid-’60s, working with the Charles Lloyd Quartet and Miles Davis’ electric band before deciding to dedicate himself to the performance of acoustic music as the leader of his own groups.

Curiously, unlike musicians as notable as John Coltrane and Sonny Rollins, he has never spent much time practicing jazz or improvisation. Although he obviously has an impressive natural gift for playing jazz, the abstention from practice seems to trace his desire to encounter improvisation uncluttered by any preconceptions.

He has always, however, practiced classical music.

“All through my life, at home,” he says, “I’ve always played Bach and Handel, the Beethoven sonatas, one at a time, over many years--all through the 32 sonatas and then starting over again. And Mozart’s on the top of the list right now.”

Jarrett has recorded and performed classical repertoire as a regular part of his agenda. His longtime affiliation with ECM Records, dating back more than two decades, has resulted in a range of classical recordings that includes Bach’s “Well-Tempered Clavier,” Shostakovich’s 24 Preludes and Fugues, a collection of Handel sonatas, and works by Lou Harrison, Alan Hovhaness and the Estonian composer Arvo Part. In September, he released a recording of selected Handel keyboard suites.

He is very careful, in his pre cise way, to make a sharp delineation between his work in jazz and classical music.

“First of all,” he says, “I can’t do them at the same time. They don’t have rocket ships that go between those planets fast enough.”

Equally important, he does not care to be described as a “crossover artist.”

“A crossover artist might be able to play a trio jazz concert within a month of a classical concert,” says Jarrett. “And sometimes they do. But I can’t. The techniques are so different. The energy types that I use don’t feel the same.”

Despite, or perhaps because of the differences, however, he does find at least one linkage between his jazz and classical music activities.

“The resonance between them is what I need,” he says. “The resonance between, let’s say, a solo concert and a Shostakovich recording, and the resonance between a Mozart concerto and a trio performance. They cannot be close to each other, but they are highly susceptible to gaining from each other.”

His jazz playing, Jarrett says, has been the winner, for the most part.

“[Playing] Mozart has improved even more the things that I was strong at anyway on the piano with the trio.”

But his classical work has also been affected by his jazz skills, especially in the area of rhythm.

“What’s lacking most of the time in the traditional classic conceptions to me is relationship to the pulse,” says Jarrett. “And that probably comes from my thinking as a . . . jazz musician, and having a strong relationship to the pulse as being something--not just being the tempo.

“It’s not quite that way with an orchestra. They’re thinking tempo as this malleable function. Whereas I like to play Mozart as though there’s really a pulse. Because I think that if Mozart was a free spirit, then he would appreciate a free-spirited accounting of his music.”

Jarrett has written a number of intriguing compositions that are indescribable by traditional stylistic definitions, “Sacred Ground,” “Celestial Hawk” and “Elegy for Violin and String Orchestra” among them. But he expresses a reluctance to write any more music.

“I feel,” he says, “that the world needs a lot of other things now than new music. Like new thinking. . . . Adding a bunch of new music to the marketplace now almost seems ridiculous. No matter how good it is.”

Does this suggest a separation from or a move away from music, as a whole, for Jarrett?

“Well,” he says, “there are times when I don’t need to hear any music at all, or play any music, for that matter. But that doesn’t mean it’s not just as precious.

“An artist looks out into the world and then relates to that world through his work. But why should that work be dictated to him? If that work is not writing or composing or playing, then it’s still work. The music is a part of me, no matter what I’m doing.”

Interestingly, having written a variety of critical letters to periodicals as well as the 1992 New York Times article--which was nominally about Miles Davis but also touched upon Jarrett’s concerns about society and entertainment--he is more fascinated, at the moment, with the power of the written word.

“The part of my persona, let’s say, which might in the past have been involved in writing my own material is now usually devoted to writing words to people who read,” he explains, adding, with a weary touch of irony, “because that’s usually the last function before they go completely to sleep.

“It’s the listening that goes first,” Jarrett adds. Then, with a slight laugh: “But they can still watch words dance across a page.”

At the heart of the matter, he appears to be expressing a need for something that is deeper than either music or words. His quest for spontaneity and an empty creative canvas, his transcendent style of performance, his desire to use notes or words or whatever it takes to reach out to people are intrinsic to a profound belief in process and “becoming.”

“And even less profoundly than that,” he continues, “basic sensitivity. Like, what does it smell like to be next to a living thing? What does it feel like to touch an organic substance? Or what does it feel like to be in a room full of organic substances--or things that have been alive?

In a society that lacks such sensitivity to such basics, Jarrett believes that “artists should just say, ‘Look, I’m going to get [a different] gig, man. This is [now] not the world that my work belongs in.’ ”

* Keith Jarrett, Gary Peacock, Jack DeJohnette (Wiltern Theatre, Wilshire Blvd. at Western Ave., 7 p.m. tonight, Tickets: $35, $32 and $27. (213) 380-5005.