Among music fans, many of us look at the annual New Orleans Jazz & Heritage Festival as a cleansing pilgrimage. The critic Simon Frith once characterized rock as a world in which "everyone is an expert — everyone knows what makes their music significant, other people’s music vacuous." But in New Orleans, all bets are off. Scattered all over the Fair Grounds racetrack on 11 stages, the festival confers as much legitimacy to a homebred, three-hit wonder like Clarence "Frog Man" Henry ("Ain’t Got No Home," "But I Do," "You Always Hurt the One You Love") as to Bob Dylan. The difference was, people laughed with Frog Man’s still freakishly girly falsetto (intact at 66 years old), whereas they tended to laugh at Dylan’s raspy croak (a tattered mess at 61). And "rock" is subsumed in a multiplicity of musics and audiences.

The festival takes place every year on the last weekend of April and the first weekend of May. This year, at the first weekend, you could catch Dylan, Frog Man, Ornette Coleman, D.L. Menard, Lucinda Williams, Jean Knight, Fats Domino, the Hackberry Ramblers, Dr. John, the Iguanas, Cowboy Mouth, Lil’ Romeo — and those were just some of the better-known acts. There were dozens more, including gospel choirs, a couple of troupes from Martinique, Dixieland jazz bands, and any number of Mardi Gras Indians.

In past years, there are have been complaints that some of the big acts were overwhelming the festival (on a big day, the Fair Grounds swells with as many as 90,000 people). A band like Phish — and their entire "tribe" — would overrun the place. But this year’s festival was considered something of a throwback — no Phish, no Dave Matthews Band, no Sting. So there was an even mix of audiences — you could see anyone at the fest. Yes, there was a fair share of what the writer Dave Hickey might call "Aryan muscle boys" — bare-chested, beer-guzzling frat boys. But there were families, too, oldsters, and a racial mix, all of which defied demographic generalizations.

Not that the musicians don’t take notice of the differences. After announcing sotto voce, "We’re going to kick your ass," New Orleans–born Sam Butera, the ageless seventysomething former music director for Louis Prima, adds, "We only play old songs. We don’t play none of that new garbage." And he and his hot-shot under-30 septet proceed to kick ass in the Economy Hall trad-jazz tent with jump-blues hits like "Jump, Jive and Wail." Meanwhile, D.L. Menard, the 70-year-old patriarch of modern Cajun songwriting, can be heard singing the Cajun national anthem, "The Back Door." Menard has been called the Cajun Hank Williams, and when he digs into the French lyrics of "The Back Door," with pedal steel guitar, fiddle, and accordion backing him, you can hear in his emotive, nasal bray a direct link with Hank. On the large, open-air Acura Stage, American Indian Dance Theater performs ritual dance as well as modern interpretations while two singers beat a four-square rhythm on a single drum, chanting in cadences that jump in register and fall in and out of rough unisons or break for solos, all to chilling effect.

Neighborhoods are what define the tribes in New Orleans. The tradition of the Mardi Gras Indians — with African-Americans dressing up as Native Americans — has its roots in slave days, when local Native Americans were said to have aided escaping slaves. But Tom Morgan, a writer, broadcaster at the local non-commercial FM station WWOZ, and a New Orleans Mardi Gras Indian enthusiast, says that the tradition probably owes as much to the natural mixing of the two ethnic groups. Congo Square, the one place in New Orleans where slaves were allowed to gather and play their music, was also an Indian trading post. My wife and I see Morgan every year in front of the early-morning Mardi Gras Indian performances, right up front.

Although Indians like the Wild Magnolias and the Wild Tchoupitoulas have become full-fledged bands, with guitarists, trap-drummers and the like, Morgan reserves his greatest enthusiasm for the more stripped-down gangs like the White Eagles and, at this festival, the Golden Star Hunters. These are groups who — like the original second-line parade bands — are built for the mobility of the street. In elaborate hand-sewn suits of multi-colored feathers and beads, they’re usually backed by nothing more than marching bass drums and tambourines, their "songs" deeply coded call-and-response raps about inner-city life. And "gangs" is the term that’s used more often than "tribes" among the cognoscenti. In the past, when Indians gathered, it wasn’t unusual for concealed shotguns or axes to be part of the mock (and not-so-mock) turf battles they enacted on saints’ days (one of the biggest, outside of Mardi Gras, being St. Joseph’s Day in March).

"This is for those in Louisiana State University . . . also known as Angola State Prison," announces Big Chief Larry Bannock of the Golden Star Hunters from the Lagniappe Stage before leading into "Shoo Fly." Nursery rhymes, gospel tunes, proto-rhythm and blues — all can be found in Mardi Gras Indian songs like "Shoo Fly," "Little Liza Jane," Indian Joe," "Hey Pocky Way, "Shallow Water," "Down by the Riverside." "Almost everyone in the African-American community knows someone who is in Angola," Morgan tells me, and that’s inevitably what "Shoo Fly" is about, with its "two white men on a big white horse." "Shallow Water" is a slave story about trying to lose a trail in shallow water.

Bannock has been Big Chief of the Golden Star Hunters since 1979, a gang from Gert Town in New Orleans’s 17th Ward. "There’s pride in being from these neighborhoods," Morgan explains. "If you say you’re from the Seventh Ward, that means something. The Ninth Ward is where Fats [Domino] is from — and everyone knows that." The real deal for Morgan and, one would suppose, Bannock are Indian gangs that are integral parts of their neighborhoods — real tribes, with a Spy Boy, a Flag Boy, a Wildman, and other role-playing attendants. The jazz man Donald Harrison Jr. has taken over as "Big Chief" from his father, the late Donald Harrison Sr., but Morgan sees maneuvers like that as something of a show-biz sham, "entertainers" rather than true community entities. "How can you be a chief without a tribe?" The Wild Tchoupitoulas, he adds, "don’t hit the street. And Larry knows how to hit the street." True Mardi Gras Indians are known to work on their suits all year ("Sewed all day and sewed all night," goes one lyric) and destroy them the day after. And the Indians have a saying about pretenders: "If you didn’t sew it, don’t show it."

VERNEL BAGNERIS was born in the Lafitte housing project built by Huey Long in New Orleans’s Seventh Ward in the late ’40s. And he’s made a career of becoming one of the city’s musical big chiefs, Jelly Roll Morton, the self-proclaimed inventor of jazz. After playing Morton in a short film called "French Quarter," Bagneris (pronounced Bahnereez) studied Alan Lomax’s Library of Congress recordings of Morton singing and telling his life story before fashioning a cabaret act and then an Off Broadway show (he also created the Broadway backstage vaudeville show One Mo’ Time). The Library of Congress recordings, he tells an interviewer at the fest’s Heritage Stage, "became a mantra for me." On stage in the Economy Hall Tent, with his long-time accompanist, Morten Gunnar Larsen, at the piano, Bagneris, dressed as sharp dude in high-waisted brown trousers and vest, purple shirt, maroon tie, and dark cap, shimmies smoothly, re-creates steps to tunes like "Ballin’ the Jack," and delivers songs like "Dr. Jazz" in an ingratiating light baritone that replicates Morton’s easy conversational phrasing (if not his nastier growls): "Hello Central, get me Doctor Jazz/he’s got what I need/I know he has."

IT’S 5:25 SUNDAY AFTERNOON, and the BellSouth/WWOZ Jazz Tent is full — even though no one is on stage and Ornette Coleman isn’t set to appear for another 15 minutes. It’s one thing for Bob Dylan to fill the field in front of the Acura Stage in oppressive conditions, but the rest of the fest is fairly mobile. People are continually on the move from one stage to the next. But everyone wants to see Coleman, the nominal inventor of "free jazz," someone who in a career of regular hiatuses has been more heard about (or heard on record) than seen. "I just want to give this a chance," one young woman tells her impatient friends as time ticks by and Coleman still has not appeared. Finally there’s a long, lugubrious speech from New Orleans free-jazz avatar Kidd Jordan explaining that this is "art," not "entertainment. By the time Coleman appears, the crowd has been reduced to an unusually reverent Jazz Fest hush. Coleman is natty, in a turquoise suit and dark straw hat. He acknowledges Ellis Marsalis and Harold Batiste for making the long trip from New Orleans to Los Angeles back in the ’50s to check him out and support his music. There’s another delay as Coleman shuffles his sheet music and gets assistance from backstage. Finally, at six o’clock, he and his trio get under way.

Who knows what first-timers think — though few of them leave to check out other acts. Here is the familiar but hard-to-describe Coleman language on alto sax — his repeated rhythmic licks of four or five notes, the bottom-to-top broken-pattern runs, the melodic asides, all in poignant speech-like patterns, all unmoored from familiar keys or time signatures yet clearly drenched in the blues. Bassist Anthony Falanga occasionally keeps straight time, Ornette’s son Denardo on drums keeps no time. There is none of the heedless, joyful fury of some of the early Coleman albums, but on the other hand "free jazz" these days gets a lot noisier than Coleman. He doesn’t shriek or scream in altissimo split tones. He just plays melodies unlike anyone else’s. There are the attractive Coleman tunes, including one with a Caribbean rhythm and a cheerful one that sounds almost standard. At one point, Falanga goes into a bowed solo that’s almost corny in its sweeping gestures. But he gradually moves down to a dissonant buzz playing on the bridge of his instrument, and Coleman joins him in a piercing high note. For a moment he and Coleman are more together than they’ve been, countering each other with jagged, laughing figures. And for a while, at least, the various fest tribes are one as well.