Erika Wennerstrom does not think she is much of a guitar player. She did not think she was much of a singer, either, until she was about 20 years old and dug up the guts to try it out in front of people.

The apprehensive songstress and guitarist heads up the trio – and is the only consistent member — originally formed in Cincinnati, but reinvented in Austin, Heartless Bastards. Bassist Jesse Ebaugh and original Heartless Bastards drummer Dave Colvin complete the band’s current line-up. The three released the group’s third album, “The Mountain,” in February.

Wennerstrom, whose powerful pipes ring reminiscent of a throatier, more emotionally-charged Karen Dalton, did not even practice singing until she was about 13.

“I always wanted to [sing], but I was kind of shy and honestly never sang too much to myself, but something inside me just told me I could,” Wennerstrom said.

That is when she discovered the perfect practice space: a greenhouse behind her family’s home in Dayton, Ohio. She says the acoustics provided within the glass walls provided church-like sounds that proved premium for working on her vocals.

Wennerstrom said she was always careful, however, to make certain no one was home to hear her crooning in solitude before she opened her mouth.

Growing up in Dayton’s heyday of music in the 1990s had a hefty musical influence on her teenage self.

“I was sneaking into bars,” Wennerstrom said. “They’d be at the bars hanging out … Guided by Voices, the Breeders, Brainiac. Even in Ohio in general, I think that off-hand sort of weight exploded. There was a lot going on.”

She never finished high school, instead opting to drop out her senior year.

“I actually had really good grades at the time but I was trying to do too much,” Wennerstrom said.

After hanging around for a while, she came to the realization that that guitar her dad had randomly sent her eons ago may prove to be a useful to comb into her songwriting and singing.

“I’ve always wanted to write songs and I always have,” she said. “I thought it’d be a good tool in helping me with that.”

So Wennerstrom went to work at teaching herself to know each string of the guitar by writing her own songs. Although even now she admits to not be very skilled in playing by ear from other musician’s work, she did a fine job on the Fat Possum compilation record paying tribute to blues great Junior Kimbrough, “Sunday Nights: The Songs of Junior Kimbrough.”

The group covered a song that struck a personal chord in Wennerstrom. After listening to the many, many versions of Kimbrough’s many, many songs, she settled on his track “Done Got Old.”

“The version I heard was acoustic, and I swear I could hear crickets in the background,” she said.

The electric aspect and drums filled in fluidly in her head, translating wonderfully to their personal recording.

Fat Possum signed Heartless Bastards when Patrick Carney, the drummer from the Black Keys, passed off one of their demos after catching a gig of theirs in Ohio.

The group released “Stairs and Elevators” in 2005 and “All This Time” in 2006.

However, following Wennerstrom and then-bassist, Mike Lamping’s painful break-up, she deemed it time to skedaddle down south to Austin, Texas. Besides various family and friends residing in town, her producer-crush, Mike McCarthy also called Austin home.

McCarthy, who had worked with artists such as Spoon and …And You Will Know Us by the Trail of Dead, harbored a mutual admiration for Wennerstrom and enthusiastically obliged to collaborate. Then “The Mountain” came.

The group’s third full-length album is jam-packed with hearty guitar parts, the occasional yodel yip and of course Wennerstrom’s dynamite vocals. It might just be Wennerstrom’s favorite album she has recorded thus far.

“I feel [this album is] the best put together,” she said. “I’m really proud of the songs I’ve done. I guess I’d say it’s the strongest, most cohesive audio-wise.”

The album gushes a sometimes-downtrodden-sometimes-exuberant alehouse rattling feel that managed to score such critical acclaim as securing them a spot performing on the Late Show with David Letterman the same month it was released.

“That was really, really surreal,” Wennerstrom said. “We were playing in Charlottesville the next day and we stopped at some sort of sports bar place. We asked to watch the TV to see the show air that night. I don’t think they believed us at first – we ended up doing shots with the bartender and the manager. It was just fun, but really surreal.”

The trio has pretty much been on the road non-stop since their latest release, playing everywhere from Santa Fe with Wilco to Bonnaroo, stopping only for a quick break in Austin, just in time for some backyard barbecuing in honor of Wennerstrom’s recent birthday.

Tuesday’s show with Jenny Lewis will not be Heartless Bastards’ first go at Jacksonville Beach’s Freebird Live venue, however, Wennerstrom said she has her fingers crossed that this time will be an infinitely better performance.

“I think I was having some major, major vocal troubles, and I could barely sing,” Wennerstrom said. “I think it was a pretty bad show. My voice went into shock. Now I know how to take care of my voice on the road. I’m looking forward to redeeming myself.”

There are certainly others out there rooting for it, too.