Heavy metal is a joke. Right? Its eldritch trappings, thudding chords, and gothic pomp make it an easy target for sympathetic parody, from Spinal Tap to Tenacious D. Yet the really funny thing is that “the metal,” as Jack Black calls it, has stealthily morphed into a new kind of art music.

“I’m really inspired by the aesthetic and spirit of jazz, like Miles Davis in the late ’60s and early ’70s,” said the guitarist Greg Anderson, who forms Sunn O))), the leading exponent of underground metal, along with fellow guitarist Stephen O’Malley. “I love the freedom of that music, the concept of pushing boundaries.”

Mr. Anderson, whose shoulder-length black hair and beard would certainly fit the period, also runs a record label, Southern Lord, which has released 70 albums since 1998. To expand on the jazz connection, the Los Angeles-based label seems to represent for the most creative factions of metal what the fabled Blue Note label did for jazz in the 1960s. Unlike Blue Note, however, which recorded both avant-garde landmarks and hard-bop standards, Southern Lord’s most popular releases tend to be its most far out. They fall into a loose category that fans call “stoner doom.”

Doom’s glacial tempos take their cues from Black Sabbath, often simulating the blurry consciousness experienced by marijuana smokers. But then it begins to free-associate, veering toward psychedelia, hypnotic drones, and a feedback-laden wash of impure sound that roots in the ambient experiments of Brian Eno and the minimalist throb of 1960s innovators like Tony Conrad and La Monte Young.

“We’re at a very cool place right now,” Mr. Anderson said. “There’s not too much analysis of what we’re doing, and that’s part of the magic.” Bands like Sunn O))) — pronounced “sun” and named after a brand of amplifier — and Boris, a Japanese trio inspired by the Melvins and fronted by a skinny female guitarist named Wata, are redefining the genre’s frontiers by essentially ignoring them. How far they’ve pushed became obvious when Sunn O))) toured as the opening act for the more conventional Swiss black metal act Celtic Frost.

Mr. O’Malley, who is now based in New York, recalled the first show, at the Fillmore in San Francisco. “I looked out at their crowd and realized we do not have a metal crowd by any means compared to this,” he said. “Imagine if it was 10,000 years ago and you had your tribe and you thought you were a metal tribe, and then the real metal tribe came over. You’d lose your territory pretty fast.”

In truth, though, the performers all come from the same place as that audience: a profoundly obsessive fanhood. Mr. Anderson makes a joke about how he first hooked up with Mr. O’Malley when both lived in grunge-era Seattle and idolized a Sub-Pop act called Earth — whose founder, Dylan Carlson, is now signed to Southern Lord. “It was all about getting really stoned and getting as many amps together as we could,” he said. After forming bands with the more conventionally metallic names Goatsnake and Burning Witch, the pair came up with Sunn O))), and Mr. Anderson launched the Southern Lord label to put out their records.

The band’s live shows often act as endurance tests for the audience, with sound waves generated as much for tactile sensation as audible comprehension, and the ever-impending threat of the so-called brown note — an extreme subharmonic rumble reputed to challenge the intestinal fortitude of more sensitive fans. Meanwhile, fog machines whir and the musicians vanish beneath the hoods of their dark monk robes.

Last year, such ritual intensity won Mr. Anderson and Mr. O’Malley a cover story in the countercultural monthly “Arthur,” which more often champions freak-folk heroes such as Devendra Banhart and Joanna Newsom. “Blacker Sabbath” was the headline, and while the musicians enjoy some of the drama inherent in metal, they also are having a bit of a laugh. The name Southern Lord indulges some of Mr. Anderson’s affection for religious imagery, but he’s the first to acknowledge its actual source. “We were drinking a lot of Southern Comfort, and listening to a lot of Lynyrd Skynyrd,” he said. “We thought it was a cool-sounding name.”

The label is even more Dixie-fied than that. The Hidden Hand, a Maryland-based band that performs tonight at Club Midway in the East Village, is one of the standard-bearing acts on Southern Lord — although front-man Scott “Wino” Weinrich has an epic reputation as a member of such defunct bands as Saint Vitus and the Obsessed. While tracks on the new album, “The Resurrection of Whiskey Foote,” deploy that exaggerated bass drone that Black Sabbath minted on “Iron Man” and evoke the seismic dread of a leviathan trawling through sludge — with a high-hat marking time — much of the record flat-out boogies. The springy rhythms and choogling guitars of “Lightning Hill” are pure Southern rock, as is the wailing harmonica that keeps up the locomotive pace. And with its song cycle about a mythic “first American” — a renegade heir to African slaves and native tribes — the album reaches for consonance with a literary landscape mapped by Constance Rourke in her classic study “American Humor.”

Mr. Weinrich, much like his peers, doesn’t analyze things too much. He credits the lyrical themes to bassist Bruce Falkinburg. “You’ll find him reading ‘The Iliad,'” he said. But the performer does enjoy telling a good story. “We still like to sing,” he said, calling from an Arby’s drive-through lane somewhere in the heartland, where his band was on tour. “Singing isn’t popular anymore.” Instead, metal vocalists are still in love with the Cookie Monster, the slang phrase for the slow, guttural “Narrrrrghhh” sound that approximates speech on many death metal recordings. Like a blues singer, Mr. Weinrich would rather belt it out, enunciating his syllables with passion and verve.

Even if its signature acts spiral off into interstellar orbits, Southern Lord remains grounded in those essential qualities. “It’s really important to have a strong voice in the underground,” Mr. Weinrich said. “Greg’s tenacity is crucial, man.”

Even Jack Black can bow to that.