Even if you've never heard of Jon Hassell, you've almost surely heard him. The trumpeter and composer's incomparable tone and knack for using his instrument as a variable-range sex toy have landed him on records by everybody from Ani di Franco, Björk and Bono to Ry Cooder and Talking Heads. He's pumped atmosphere into a slew of movies and TV shows too.

Factor in samples (how many people have bitten "Remain in Light"?) and a horde of imitators prone to popping up everywhere from coffee shops to porno soundtracks, and he comes out smelling like brass' most pervasive presence since Miles Davis -- whose music he credits with saving him from a classical career -- walked the planet. So why, again, is Hassell's current U.S. tour his first in 20 years?

"It's mostly just a matter of timing and demand," Hassell, who performs Thursday at Walker Art Center, explained by phone from his home in Los Angeles. "Europe really embraced what I do early on; I've had so many opportunities to play there that I never really had time to ponder the question. Things just happened to come together for this tour."

Those things include "Last night the moon came dropping its clothes in the street," newly out on avant-mellow institution ECM. While peer-group popularity is great for his soul and bank account, it's the fruits of the solo career Hassell launched with 1974's "Vernal Equinox" that moved many of the people who saw him at the Walker in '89 to buy tickets for this week's show immediately upon hearing about it.

Easily Earth's most listenable experimentalist, the former student of Karlheinz Stockhausen and legendary vocalist Pandit Pran Nath has, over the course of a 40-year career, created a constantly evolving world informed in part by Western and Indian classical traditions, ambient music, jazz, dub, hip-hop, pygmy ensembles, nature sounds, street noise -- essentially anything involving vibrating air molecules.

Hassell's other passions of the moment -- literary, spiritual, sensual, whatever -- lend his creations added depth and resonance, as does the disconnect between intellect and sensuality that he explores as a first-time author in "The North and South of You: Making the World Safe for Pleasure." He'll be discussing the nearly completed book (among other things) with longtime friend and occasional collaborator Brian Eno at London's Queen Elizabeth Hall in April.

It's his genius for cross-pollinating all of the above and electronically dressing the results for pleasure that gives "Last night......" much of its genre-transcending appeal -- but not all. Verdant as a tropical rain forest and doubly mysterious, Hassell's 18th solo album finds him more adept than ever at populating his world with the "motifs" -- little snatches of melody and/or texture subject to all kinds of variation -- that seem more and more like forms of artificial life.

"Some of the motifs are inspired by animals," says Hassell. "I'm a great lover of natural sounds, and of music from the folkloric tradition ... stuff that happens out of some kind of inner necessity rather than being motivated by money or fame. The motifs also play a narrative role, within both the album and my work as a whole. No offense to anybody, but I'd never want to be like Mark Rothko and paint the same picture over and over. By the same token, I like the idea of providing some kind of continuity over time. At least one or two motifs on the album go back to the '70s."

The motif wrapped around the spine of "Abu Gal" goes back farther still if you count the source material: It's based on a shard of verse from Duke Ellington's "Caravan." For Hassell, the quote does triple duty as salute to a significant ancestor; as heat source (while relentlessly smooth, Hassell's music almost always smolders at its core), and as sonic component of the lifelong obsession behind his book.

"It's a combination of text and images," he says, "but I've worked really hard to make it clearer and less gimmicky than, say, Marshall McLuhan's 'The Medium Is the Massage.' Clarity and simplicity sometimes count for a lot. I'd love it, for instance, if somebody could explain the current state of the economy to me in two or three pictures."