Charleston-based country/rock/indie duo Shovels & Rope lived the life of a struggling act for years before releasing its latest album, “O’ Be Joyful.”

The multi-instrumental husband-and-wife songwriting team of Cary Ann Hearst and Michael Trent lived, worked and played on a small budget, traveling and recording with little outside assistance. But they created beautifully melodic, twangy, stompin’ songs in their own way with little worry or distraction.

A lot of fans in the Lowcountry and around the Southeast have been tuned in to Shovels & Rope’s rich music over the past four years, but the rest of the country (and the world) is quickly catching on, too. Hearst and Trent will climb another notch this week with an appearance Wednesday night on CBS’ “Late Show With David Letterman.”

Released in July on the Dualtone label, “O’ Be Joyful” has caught the attention of major publications, radio stations and music critics over the past five months. They’ve earned glowing reviews, praise and attention in the national music media from coast to coast.

“The record definitely came out the way we wanted, but we didn’t necessarily have an expectation for the final result,” Hearst says. “We were really pleased with it. Michael engineered and produced the record, so I had the privilege of having fresh ears all the time. I worked hard on my parts and helped direct it, but it was something that he really labored over.

“I’m lucky that I didn’t have the kind of recording fatigue that so many musicians have when they’re in the studio. I was excited every day with the results,” she says.

With the “Letterman” performance and a lengthy winter tour set to launch the next day, Shovels & Rope could blow up for real.

“Michael and I didn’t have a pot to p--- in for years and years,” Hearst says of the duo’s leanest days. “Now we have ... a really nice vehicle, which we’ll be driving for years to come. Michael and I have always been very cautious with every investment into the business side of the band. We don’t like too much risk, and we still operate on a shoestring budget. We put a lot into getting this record out there and promoting it.”

Years in the making

Through the late 2000s, Trent and Hearst performed mostly as solo singer/songwriters. They often collaborated with mutual friends in the local band scene, but they didn’t focus on developing Shovels & Rope until 2010.

Trent came from years of full-band collaborations with the Films and other pop/rock projects.

Hearst already had established herself as a solo singer/songwriter with a slew of original songs and a versatile repertoire of country, blues, gospel and rockabilly standards and gems.

At small bars and local music venues such as the Pour House, Tin Roof and Tattooed Moose, Hearst and Trent usually arranged stacks of vintage amps, cheap keyboards, old guitars, miscellaneous hand percussion and a junky drum set.

Their stage gear looked rickety, but their energetic performances and rich harmonies were elegant and emotive.

“We’ve really learned how to sing well together just from doing it so much,” Trent says. “And we’ve learned how to read each other’s minds, too. We can communicate with each other very easily on stage.

“We’re trying to experiment with the instrumentation a little bit, getting away from the basic guitar-and-drums thing. We try to throw some new trick in there and keep the show fresh. We’re getting better at singing together and writing good songs that tell good stories.”

Hearst’s lyrics and delivery lead the way on most of the songs on “O’ Be Joyful,” from the minor-key, country-styled opening, “Birmingham,” to the porch-stompin’, fuzz guitar-accented title track. Trent’s scratchy baritone complements Hearst’s high tones and yelps.

“I think we’re turning into The Everly Brothers,” Hearst jokes. “People sometimes ask us if we’d played in bluegrass bands because of our acoustic instruments and harmonies. We’re not rock ’n’ roll and we’re not country, and we couldn’t be further away from bluegrass in a way, but so many great singers and harmonizers came out of that tradition.

“But we only have four hands and four feet between us to accomplish what we do. I know that my voice is my strongest instrument, and I think that the vocal harmonies have naturally come to drive a major part of our sound.”

National attention

Shovels & Rope’s sounds attracted attention in unusual places this fall and winter from newspapers, magazines, websites, radio stations and television shows outside their usual underground and independent media avenues, including the The Wall Street Journal to The New York Times.

National Public Radio featured Hearst and Trent in a 20-minute performance/interview episode of “Favorite Session” on their video page in September (via Seattle’s KEXP station).

Nashville-based bimonthly magazine American Songwriter also sandwiched the duo between Bob Dylan, Neil Young and Leonard Cohen on its “best-of-the-year” list in December. It was one of dozens of periodicals and webzines that placed Shovels & Rope at the top of year-end lists.

Both Hearst and Trent seem to have dealt with all of the praise and hoopla in stride. But there’s plenty more on the horizon for Shovels & Rope.

The duo recently recorded new material in Nashville, and it will embark on its winter tour through the Northeast on Thursday with an already-sold out concert at the Bowery Ballroom in New York City. The road trip will wind down the East Coast and make a stop at the Charleston Music Hall on March 2 (advance tickets for that show still are available).

A documentary on the band is nearing completion this year as well. Independent filmmaker Jace Freeman and his Nashville-based production company, Moving Picture Boys, shot and edited footage of the duo last year for a forthcoming release titled “The Ballad of Shovels and Rope” (due sometime this spring).

“I think people are a little bit interested in our story as much as they are about the album itself, because we’re a married couple slogging it out on the road, and we have been for a while,” Trent says. “We were both separate songwriters who had to check egos at the door and create a cohesive thing. Maybe that has something to do with it.”