Louisiana’s Lil’ Band o’ Gold make the best case I’ve yet heard for rock ‘n’ roll as folk music. Their sound is rooted in the late-50s blend of R & B rhythm, Cajun harmonies, and country sentimentality that became known as “swamp pop,” and the band’s synthesis of those influences–notwithstanding its polished modern sound and occasional power chord–makes it possible to hear how gulf-coast rock evolved from the folk genres of the region. The nine members span nearly three generations: the front line includes roots-rock guitar firebrand C.C. Adcock and nouveau Cajun vocalist-accordionist Steve Riley, both in their early 30s, and the group is anchored by 65-year-old drummer Warren Storm, whose 1958 ballad “The Prisoner’s Song” helped define swamp pop. The Lil’ Band o’ Gold’s eponymously titled debut, released in 2000 on Shanachie, collects an eclectic mix of covers and a few originals. Their version of the late-50s ballad “Shirley” marries chugging boogie cadences and teen romance in flawless sock-hop style, and they recast the Balfa Brothers’ anthemic “Parlez-nous a boire” (“Let’s Talk About Drinking”) as a ragged, high-octane road song, though of course that road runs through Lafayette–Pat Breaux’s saxophone bleats and slobbers, Riley’s accordion rocks and wheezes, and he and fiddler-turned-saxist David Greely caterwaul with whiskey-soaked abandon. Storm delivers “Please Mr. Sandman” (no, not the Chordettes tune) in a tone so self-consciously weary and wounded that he sounds like he’s making fun of his own heartbreak–after all, it’s a cherished tradition in pop music to take a rubbernecker’s morbid pleasure in a lovelorn chump’s travails, even when the chump is you. But things get serious on keyboardist David Egan’s “First You Cry”; sounding eerily like Percy Sledge, who covered the tune in 1994, Egan summons the parched intensity of a man who’s run out of tears. The Lil’ Band o’ Gold headlines the first day of the Old Town School’s Folk & Roots Festival; for a complete schedule see the Fairs & Festivals listings. Saturday, July 13, 8 PM, Chicago Folk & Roots Festival, Welles Park, 2333 W. Sunnyside; 773-728-6000.