Milford Graves and Jason Moran were listening hard at the Big Ears Festival on Friday evening, and in this they were far from alone. Their spontaneous musical dialogue, onstage at the elegant Bijou Theater in Knoxville, Tenn., suggested a merging of the ancient and the ultramodern, aglow with an ephemeral sort of grace. At one point, Moran's deep, mournful sonorities at the piano led Graves toward a murmuring hush at the drums, as if anything else would break the spell.

Musically speaking, this was a first-time encounter for Graves, who at 76 is a sagacious elder in the improvising avant-garde, and Moran, 43, whose career has branched out from a position closer to jazz's center. Their concert was a gemlike centerpiece of Big Ears 2018; capacity at the Bijou is 700, but even with several competing options on the schedule, a lot of people were turned away.

Standing in line, I struck up a conversation with a white-bearded Tennesseean who has never missed an edition of the festival. When I asked whether he'd been looking forward to Graves and Moran, he said he didn't know a thing about either one. His eyes lit up as he said it, like a kid about to open a birthday present. He wasn't a rare-sound partisan, or a practicing connoisseur; he had just learned to count on musical discovery at Big Ears. "The more bizarre, the better," he told me.

Big Ears will do that to a person. Contained within a walkable radius of historic downtown Knoxville — in a range of ornate landmark theaters, refurbished industrial spaces, art galleries, churches, and clubs — it creates its own atmospheric climate, along with a center of gravity. From its first iteration in 2009, the festival has been a locus of expedition, defined more by a go-anywhere ethos than by any style or genre allegiance. For a few years, the event honored vanguardist classical composers like Terry Riley and Steve Reich. It has skipped some years over the last decade. This was its seventh edition — and my first, despite the best of intentions and the deepest of affinities.

What led me to Big Ears this year, in part, was an unusually high quotient of experimental jazz — or one or another form of unnamable music, like Graves and Moran's spirit trance, that bore a vestigial relationship to jazz. Increasingly, improvising artists across the style spectrum are accessing multiple vocabularies, reconciling divergent strategies, bringing other disciplines into the frame. This coalescence was also a hallmark of last summer's Ojai Music Festival, programmed by pianist and composer Vijay Iyer. Like that inspiring event, which featured a few of the same artists, this year's Big Ears felt right in tune with an emergent, exhilarating frontier. I see this not only as a hopeful turn in the festival's model of inclusion but also as an indicator of present-day permissions around jazz's state of the art.

Moran is an obvious case in point. Along with the Graves duo, he played a show at the Mill & Mine, around midnight, with his Fats Waller Dance Party, creating a hallucinatory funk jam inspired by one of jazz's foundational heroes. He also performed at the Bijou with BANGS, a trio that released one of my favorite albums last year and sounded even better here.

BANGS is all about Moran's sensitive, shifting rapport with guitarist Mary Halvorson and cornetist Ron Miles, who each brought furious concentration to the task. Sometimes it sounded unmistakably like jazz, sometimes not. A seamless progression from the austere beauty of "White Space" (by Halvorson) to the pastoral reassurance of "Cupid" (by Miles) imparted the sensation of pure possibility, an open road under a billowing sky.

The festival abounded with other manifestations of this improv-activated, beyond-the-known-horizon sort of music, too many for a laundry list, let alone a concert agenda. But among other things: the formidable British saxophonist Evan Parker playing both a cathedral recital and in a pair of futuristic bands, his Electro-Acoustic Ensemble and the collective Rocket Science; a solitary explosion of sonic dimensions by trumpeter Peter Evans; two views on the violinist Jenny Scheinman, who first led Mischief & Mayhem, a raucous jazz-rock unit with Nels Cline on guitar and later presented 'Kannopolis: A Moving Portrait,' a found-footage-and-string-band experience steeped in Carolina twang; and the Tyshawn Sorey Trio, which developed like a high-pressure front, in an inexorable gyre.

The pianist and reliable sound sorcerer Craig Taborn, whom I heard in four distinct contexts over the weekend, played the festival's final slot with his superdynamic quartet. Introducing the band, which appears on his 2017 album Daylight Ghosts, he gave a shout out to the Big Ears brain trust, "because it's a festival that kind of represents how I listen to music."

Ashley Capps, the founder and artistic director of Big Ears, would say much the same. He did, in fact, over breakfast on Friday morning. "It kind of unfolds with a logic of its own," he said of the festival's programming calculus. "But sometimes there's something in the air. A clear association with the cultural moment."

In the music industry, Capps is probably best known as a cofounder of the Bonnaroo Music and Arts Festival, which has sprawled out from a baseline of jam-band exuberance — this year's headliners include Future, Paramore and Eminem. But Capps started out promoting shows in Knoxville during the late '70s, and ran an eclectic club called Ella Guru's in the '80s. "For people who've grown up with me and know my taste," he said, "they're surprised it took so long for jazz to have such a prominent place at the festival."

The tipping point, he said, was a 2016 Big Ears appearance by the brilliant, sometimes inscrutable composer and multireedist Anthony Braxton. "He played in the Bijou, and that was the first time we had done shows on a Friday afternoon," Capps recalled, painting a picture just like the one I saw with Graves and Moran: full house, little to no turnover, 200 people shut out in line. "It was so encouraging to me as a programmer or a curator, to realize that we had managed to attract an audience with that level of interest and curiosity."

Since then, Big Ears has featured saxophonist and flutist Henry Threadgill and trumpeter Wadada Leo Smith, who like Braxton are longtime members of the Association for the Advancement of Creative Musicians (AACM). Two of the most galvanic performances I saw were by a guiding elder of that organization, the multi-reedist and composer Roscoe Mitchell.

The first was a tumultuous show at The Standard, a converted warehouse where I also saw portions of sets by Rostam and Algiers. Mitchell was leading Trio Five, featuring the younger rhythm team of bassist Junius Paul and drummer Vincent Davis, who met his volcanic outpourings with power and poise. After a long stretch of circular breathing on soprano saxophone, expressive and atonal, Mitchell cued up "Odwalla," a swinging theme he composed for the Art Ensemble of Chicago.

The same anthem closed Mitchell's concert at the Bijou on Saturday night, with a nine-piece confab similar to the one on his double album Bells For the South Side, released last year. Sorey and Taborn were there alongside Mitchell associates like Hugh Ragin (trumpet), Tani Tabbal (drums) and James Fei (electronics and saxophones). As on the album — which was recorded in 2015, as part of a 50th anniversary celebration for the AACM — this performance began in a stark, accretive mode and gradually led to an incredible, wildly cacophonous squall.

Capps, who first presented the Art Ensemble of Chicago at the Bijou in 1980, told me that this performance felt a bit like coming full circle. And he agreed with my suggestion that after decades of marginalization, the AACM had finally begun to see its restless, collectivist methodologies metabolized into the improvised-music mainstream, at least up to a point.

"There's a certain parallel with, say, minimalism — Steve Reich and Philip Glass, the stuff in the '70s," he said. "It was totally fringe; they had to form their own bands because nobody else could play it. I think the AACM is part of that tradition. It's been 50 years of not only putting these ideas out there, but also building a community around the ideas."

Big Ears represents another expression of that community, even if its convergent superabundance is as fleeting as a dream. For all the enlightened sprawl of its programming, which also included a heavy infusion of traditional Appalachian music this year, Capps said his curation was driven first and foremost by a sense of urgency. "Many of these musicians are now in their 70s and 80s," he said. "Their contribution to art and culture has been profound, for me and for so many others. And I want to acknowledge them and honor that."

Mitchell and Parker were two shining embodiments of this, avatars of uncompromising vision and intergenerational exchange. So too was Milford Graves, who performed a separate solo-percussion-and-vocal concert at the Bijou, to a rapt full house. At one point, after a casual demonstration of mystical Cuban rumba, he stopped to catch his breath. "It's all in there," he said of his flowing access to the music. "There's no free jazz, no avant-garde, no bebop."

He paused, magisterially, and then perked up. "Hey, check this out," he said, suddenly sounding like a guy handing out flyers outside a hardcore show. "Tomorrow night, Jason Moran and myself. It should be interesting."

Beyond Jazz

In the Big Ears spirit of roving interests and genre defiance, here are five great performances with little, or no, connection to jazz.

Arto Lindsay, The Mill & Mine

The always unclassifiable guitarist, composer and singer Arto Lindsay made this show a fever dream of growling funk, leading a band with Melvin Gibbs on bass, flanked by two excellent drummers. It was political, too — and not only when Lindsay dedicated a song to a black feminist activist who was killed earlier this month in Rio de Janeiro, Brazil.

Bang On A Can All-Stars: Julia Wolfe's Anthracite Fields, The Mill & Mine

Julia Wolfe's new-music oratorio for choir and chamber sextet, which won the 2015 Pulitzer Prize for Music, is a haunting elegy inspired by the plight of Pennsylvania coal country near the turn of the century, and Anthracite Fields was all the more haunting in the cavernous dark of The Mill & Mine, where much of the audience sat cross-legged on the floor.

Béla Fleck & Abigail Washburn, The Jig & Reel

Hours earlier, they were onstage at the Tennessee Theatre, an exquisite hall whose décor has often been likened to the inside of a Fabergé egg. This pop-up show was a lot smaller and scruffier. But where better to hear Washburn's clarion voice and clawhammer banjo — deftly backed by Fleck, her husband — than in an old Scottish pub in Eastern Tennessee?

Laurel Halo with Eli Keszler, The Standard

During an afternoon interview with music critic Ben Ratliff, the experimental electronic artist Laurel Halo and the drummer Eli Keszler talked about their formative influences, free jazz among them. That evening they made an ambient music of shifting layers, hallucinatory at times but rooted in body movement.

Julie Byrne, The Standard

Interiority is a generous condition in the music of Julie Byrne, who worked here with an understated command, singing in a warm, floaty hush and lightly fingerpicking her acoustic guitar. She had two supportive band members, on synthesizer and violin, but what mattered most were her songs, which could feel like spaces to crawl into and disappear.