She was nervous. Panicking for months. Living with uncertainty.

Twin Cities singer Judi Donaghy Vinar felt lost going into her first concert with Bobby McFerrin and his 12-person vocal ensemble.

"I didn't know what we were going to be doing. I literally didn't have a clue," she recalled. "There's no rehearsal. I don't know anybody in this group except Bobby. I didn't know what to wear."

She went to sound check and listened. Then she had a clue.

Vinar has learned to wing it with McFerrin. Her first nerve-racking gig with his Voicestra ensemble came in 2001. But she started working with the master vocalist in 1997, with a group of a dozen Twin Cities singers who met every Thursday for a year and a half as part of McFerrin's writing project.

Now she feels at home with McFerrin and Voicestra.

"It's pure joy. It's absolutely fun and it's inspiring," she said.

Vinar, a private voice teacher who headed the vocal department at the now-defunct McNally Smith College of Music for 15 years, has performed locally with the Wolverines Classic Jazz Orchestra, the Girls and Lori Dokken, among others. For 25 years, she's been a soloist at Unity Christ Church in Golden Valley, where she also directs the choir.

Vinar spends a week each year with McFerrin as part of the faculty at his Circlesongs vocal improvisation workshop in upstate New York.

Now Vinar knows the Voicestra routine, whether it's 12 singers or just four, as will be the case at the Dakota this week.

Sound check is their warmup. Before taking the stage, they stand in a circle, put a hand over each other's heart and pray. Then it's improv time.

"The most common structure is either Bobby or one of us will just start with an idea and just sing what's in the air. It turns into something. It has a pattern to it," Vinar explains. "Once we find that pattern, then we can teach it to the other singers. Then you improvise on top of that or around it, creating another part. Most of the time you end up with four interlocking parts. Then you shut it down like you built it up."

Each time becomes "brand-new music and it's only going to be done once," Vinar noted. "That's kind of precious and super-exciting."

Sometimes she remembers what they did, but oftentimes she doesn't.

Vinar vividly recalls a 2007 Voicestra concert in Blacksburg, Va., the week of the shooting there at Virginia Tech University that killed 32 people.

"One of the most moving concerts we've ever had," she said. "We were already scheduled there. What was on our minds is how do we make music while people are in deep grief? Bobby started the concert by creating this hymn-like sounding thing and then he created parts for us. In fact, that day we just morphed from one idea to the next idea without stopping. It was like a straight hour of singing. I think it was really, really healing."