Given the silly name and bright, Simon & Garfunkel-inspired harmonies, Brooklyn folk-rock act Girlyman sounds like it was born out of a happy place. The thing is, it wasn’t.

“Our first rehearsal was scheduled for Sept. 11. We were putting together press kits and complaining about how crappy doing it was … what an upstream battle it was getting your name out there,” said singer and guitarist Doris Muramatsu, describing that day in 2001. “Then it happened. For all of us, it was a wake-up call, and music felt like a necessity. It felt like something we needed just to experience joy again, and there was no doubt in our minds that being in this band was what our calling was.”

Those events not only gave an urgency to the band, but also a light undertone, stemming from the perspective rewarded in 9/11’s aftermath, and manifesting itself in the tongue-in-cheek moniker.

“You realized not to take things so seriously. We knew just to do it for the fun and joy of it,” said drummer JJ Jones, formerly of Po’ Girl.

Audiences at Sunday’s show in Norman will witness how that approach has taken Girlyman from playing to handfuls in coffee shops for a $12 payday to supporting Indigo Girls on tour and having a music video directed by comedian Margaret Cho.

The momentum nearly came to a halt when Muramatsu was diagnosed with leukemia in late 2010.

“We thought that was it. No more touring, no more recording,” she said.

“I found out it was a treatable form, but it was challenging even still through my recovery. I couldn’t see how we were going to make another album, but we did.”

With cancer in remission, Girlyman recorded the soon-to-be-released “Supernova.”

“It’s a dying star,” Jones said. “They give birth to new stars in the energy they shoot out, and that made so much sense this year, because it felt like something was dying, but then there was a whole new wave of transformation and hope that came out of it. The whole record really reflects that.”

Not coincidentally, the disc is Girlyman’s loudest and liveliest to date.

“It’s not a folky sound. It’s a full, rock sound,” she said. “It was like, ‘Wow, we’ve really changed.’”