Hans Deryk, Associated Press
Audience participants perform "Flock" at the Carnival Center for the Performing Arts in Miami.

MIAMI — An usher handed me a black cap with half a plastic baseball affixed to the top.

"This is your magical performance hat," he said, turning on a light under the baseball to make the half-globe glow. "This hat is going to drive your performance tonight."

I groaned silently and told myself: This is going to be awkward.

For the sake of experiencing a new type of music, I had signed up to take part in an interactive performance called "Flock" at the Adrienne Arsht Center for the Performing Arts of Miami-Dade County. I knew I was going to be part of a social and musical experiment. I knew I was going to have a role in making the music. But headgear wasn't part of the original deal.

I'm with the band

To be fair, I did have some advance warning about the hat. The evening's mastermind, Georgia Institute of Technology music professor Jason Freeman, broke the news over tea at a bookstore a few weeks before the performance.

Freeman — a 30-year-old, bespectacled musician and self-described computer geek — graduated from very traditional music programs at Yale and Columbia. But he says he wants to change the way people experience music — often, by sitting passively in a dark hall.

"You're in this big room with this incredible music being created onstage but, well, I at least don't feel like I'm much a part of it," Freeman said. "It's like I'm watching something amazing happening rather than feeling part of it."

Freeman envisions an atmosphere more like a rock concert or a baseball game, where the crowd feels connected to what's going on at center stage. He says some of his most memorable musical experiences have involved performing, and he wants to share that with his audience. Instead of handing out cellos or kazoos, however, he uses technology to help audience members influence a performance.

An example: In 2005, he handed out light sticks at New York's venerable Carnegie Hall and asked concertgoers to flick them on and off. The resulting display helped direct an onstage orchestra.

The logical next step? A glowing hemisphere mounted on a baseball cap.

Freeman explained what was in store for me and the other "Flock" participants:

An overhead camera would track our movements in a performance space, and a computer system would translate our positions into instructions for a saxophone quartet. The musicians would roam with us, reading and following the instructions on PDAs.

The overhead camera, it turns out, has an easier time tracking people if they wear lights on their heads.

A little mayhem

On performance night at what was then called the Carnival Center for the Performing Arts, the gathering of 40-odd audience members in illuminated hats was an impressive spectacle. From a balcony it looked like a congregation equipped with glow-in-the-dark yarmulkes. On the floor was the outline of a square, surrounded by a ring of chairs and four projection screens.

As I entered the space, a second usher encouraged me to see what would happen if I walked into the square. I did, and a dot appeared on the projection screens, accompanied by an electronic sound. If I stood still, a white light appeared above my dot, as if it was getting beamed up to the starship Enterprise; when I walked, the light became vaguely helix-shaped.

"Look, I'm a DNA!" shouted one woman who noticed her helix.

We didn't have long to experiment. We were asked to be seated and the music started, with the saxophonists and four dancers pacing and leaping around the square.

I was paying attention but also wondering: "At what point am I going to be asked to get up?" It didn't take long before we were all ushered out of our seats and into a series of lines.

A dancer had one of the lines start a step-touch dance step. I looked at the woman standing uncomfortably next to me.

"They look like they're having more fun," I said, and we started step-touching, too.

Dancers distributed cards telling some people how to move about, and barely controlled chaos ensued. At one point in the 90-minute performance I looked over a saxophonist's shoulder to see what was on his PDA screen: smears of different colors representing notes. At another point, I was convinced a saxophonist was following me.

A conga line formed, and I gleefully joined it.

"I've lost my husband," a woman told me.

"We're going to do this until 10 o'clock?" another asked.

While I awaited further instructions, a young woman took matters into her own hands, running from one corner of the box to another. Let's participate in a little mayhem, I thought, and several of us joined her.

Method to the madness

Was all this movement mattering? I had no idea. Honestly, all the running around distracted me from listening to the music, which ranged from a sort of Caribbean sound to discordant noise, from electronic music to jazz.

Eventually, the dancers and saxophonists signaled the end of the performance by walking off stage, and the man behind the madness appeared.

"My name is Jason Freeman and you can blame me for everything that happened tonight," he said.

The audience applauded, then the questions came. Most notably: "How exactly did we influence the performance?" I was wondering, too — Freeman had hinted at his methods to me beforehand, but hadn't shared all his tricks.

The box on the floor, it turned out, was like a measure of music. If you were close to the left side you created notes at the beginning of the measure. On the right, you created notes at the end. Moving to the top of the box produced higher notes; to the bottom of the box, lower ones.

Simple enough. But some people said they wished they'd known this beforehand to better track their impact on the music.

One of Freeman's main goals, though, was for us to simply have fun. Which I did.

Still, at the end of the night, I was glad to turn in my magic hat and get back to being slightly more anonymous.