Phox conveys natural grace as a moodily atmospheric folk-pop group. But frontwoman Monica Martin, whose languid voice wafts through the sextet’s sepia-toned textures, was never a natural when it came to performing.

“I didn’t sing in front of people because it scared me,” says Martin, 25, who grew up in the tiny Wisconsin city of Baraboo along with her bandmates. “I was just terribly shy. My anxieties were crippling, to be quite honest. They still trouble me, but I’m getting a lot better. My life and my heart have changed so much.”

Indeed, a lot has changed during the past two years for Phox, who went from an early appearance at London’s iTunes Festival to shows at the Newport Folk Festival and in Boston, where the group plays Brighton Music Hall on Valentine’s Day.

Martin was in her late teens, dating guitarist/trumpeter Matt Holmen, when he first heard her sing, harmonizing to a CD in the car. “He was like, ‘What was that?!’ ” she recalls with a laugh from Wisconsin. “Five years later, I finally caved and said, ‘Fine, I’ll sing in front of someone.’ ” Holmen had just started playing with their future bandmates, and they needed a singer.

“The thing about Baraboo is even if you don’t know someone intimately, you know them,” Martin says. She had taken a math class with keyboardist Matteo Roberts, whose brother Dave plays drums. Multi-instrumentalist Zach Johnston and bassist Jason Krunnfusz had been grade school chums of Holmen and Roberts. But the defining factor in the band’s formation came when they all leased a house in nearby Madison.

Martin had been to beauty school and was working in a hair salon. “I didn’t know what you had to do to function as a music group, and I was fairly lethargic,” she says. “If we all lived in different places and we had to plan a meeting or get together to practice, it never would have happened. You can’t say, ‘No, I’ve got an appointment,’ and the answer is ‘No, you’re in the living room and watching TV.’ ”

The group began to produce and distribute music and videos, taking advantage of various members’ skill sets. Johnston had worked as a filmmaker, Holmen was a graphic designer into animation, Dave Roberts was an audio engineer, and Martin did photography. “We all had our hands in different facets of art that are essential to putting together your media,” she says. “It sounds very businessy, but it didn’t feel like that, because it was just something that we gravitated toward anyway.”

Band members’ broad musical tastes range from pop to classical, though Martin says they can all agree on orchestral indie-pop auteur Sufjan Stevens and progressive string band the Punch Brothers as artists they like. Raised on soul and Motown, Martin was inspired by Feist, Regina Spektor, Fiona Apple and—vocally, in part because of similar tonal breaks in her phrasing—Brandi Carlile.  “I was like, ‘Wow, someone’s voice does that thing that my voice does, but it sounds nice.’ ”

Songwriting posed another challenge on the road to Phox’s eponymous 2014 debut, as Martin wrote tunes she “didn’t think anyone was going to hear,” laced with fragmented references to both family and romantic relationships.

“A melody will come to me, and there’s already a spirit to the melody,” Martin says. “Is it sad? Is it hopeful? And at the same time, I’m always writing down my thoughts.” Next, the singer presents her sketches to the rest of the band, usually through Holmen, who she calls “my go-to person, my platonic life partner.” She’ll flesh out bridges with Matteo Roberts or Johnston, while members add accents such as the banjo, clarinet and whistling in “Slow Motion,” one of the album’s highlights. “We start working on it acoustically—and work on harmonies,” she says. “Then it becomes a hot mess where everyone throws every idea in, and we reduce it.”

Songs for a follow-up are “in utero,” Martin says. “I’m already starting to play the songs in a casual way to the boys,” she offers. That, she says with a knowing confidence, “is something that never would have happened two years ago.”

Phox plays Brighton Music Hall on Feb. 14.