Sherman Holmes laughs. A lot. He laughs like he talks, in a wise, raspy and resonant tone. Each burst at the end of his laid-back sentences is a song unto itself.

That same voice along with those of Wendell Holmes and Willie “Popsy” Dixon will be on stage for three performances as part of Bangor’s National Folk Festival. They will play at 8 p.m. Friday, Aug. 23, on the Kenduskeag Dance Stage; at 3 p.m. Saturday, Aug. 24, on the Heritage Stage in Gomez Park; and again at 5 p.m. that day on the Kenduskeag Dance Stage.

For nearly 33 years the trio – Sherman on bass and vocals, Wendell on guitar and vocals, and Popsy on drums and vocals – has toured and recorded as The Holmes Brothers, one of America’s definitive roots musical groups. Their music is a mix of blues, gospel, soul, R&B, and country all treated with their unique style of beautiful three-part vocal harmony.

On the group’s latest release, “Righteous: The Essential Collection,” the musicians deftly cross back and forth between hipster cool and holy soul on each single, from their original compositions to their renditions of Tom Waits’ “Train Song” and The Beatles’ “And I Love Her.”

“We’ve become more focused,” Sherman said of the group’s musical evolution over the trio’s long career. “When you’re a jack of all trades,” he continued, “sometimes you’re a master of none, you know.”

The group’s biggest asset might be its reluctance to adhere strictly to a single style. Firmly rooted in blues and gospel traditions, The Holmes Brothers succeed at infusing a bit of each of America’s most cherished musical forms – soul, R&B, blues and gospel – into every song they play. Each song is an inspired work, distinctly Holmes Brothers, distinctly and soulfully American.

Raised in Christ’s Church, Va., Sherman and Wendell Holmes grew up singing at home and at church, which Sherman says affected his musicianship “both directly and indirectly.” His real musical education, however, occurred along with his younger brother Wendell in the small and smoky clubs of 1960’s New York and New Jersey. The current Holmes Brothers line up came together when Wendell and his friend Popsy joined Sherman and harmonica player Bill Dicey in 1979. The group played together shortly as a four-piece band before Dicey left the group.

A successful live band for decades, it was 1989 before the group made its recording debut. By 2001 the trio had grabbed the attention of Grammy-award winner Joan Osborne who joined the group as back-up singer and producer on the release “Speaking in Tongues.” The group plans to record again this October. And as for that next record, “I keep my fingers crossed every time,” Sherman joked.

But for the 63-year-old Sherman, playing live is still where it’s at. “I love touring,” he said. The trio proves that every year. The band recently returned from festivals in England, Italy and Singapore and will play a few other festivals in New England before coming to Bangor.

“I like playing festivals ’cause they give you more exposure,” Sherman said. “You see musicians you haven’t seen in a while, too.” He said he likes the small clubs, too. For a group like The Holmes Brothers, whose slightly sluggish record sales hardly match their critical acclaim, winning over one audience at a time is downright noble.

“I think it’s important, too,” Sherman said of the festival experience. “[People] meet other people, talk, and might learn things they might not know. I think festivals are great. They bring people together, you know.”