Close your eyes and picture an orchestra. What's the first thing that comes to mind? For some people it will be the ranks of violins, for others, the timpani or the trombones. But for many of us, the first image we conjure is of a black-clad figure, standing with his or her back to the audience, arms raised, baton in hand: the conductor.

String quartets, rock bands, jazz trios -- they all get by without conductors. Once a group tops eight or nine musicians, though, a conductor seems almost mandatory. Without a conductor, who would set and maintain the tempo? Who would cue the players? Who would tell the trumpets when they're drowning out the piccolos? Without a conductor, could an orchestra even function?

For the 24 members of the newly minted Stanford Collaborative Orchestra (SCOr) the answer to that last question is an emphatic yes.

SCOr held its first rehearsal in April of this year. By the end of May, the student-run group was performing works by Aaron Copland and Sergei Prokofiev before a full house in Stanford's Toyon Hall. That's a short time frame for any all-volunteer ensemble to go from zero to audience-ready. It's all the more impressive because SCOr accomplished this feat -- you guessed it -- without a conductor.

As for how they did it, the answer, according to bassoonist Stephen Koo, is "democratically."

Koo, along with violinist Linda Yu, is one of the co-founders of SCOr. Both are Stanford students and Palo Alto natives who have played in a variety of traditional orchestras and ensembles since grade school. Last week, with SCOr's premier performance (and spring finals) safely behind them, both were eager to talk about the Stanford Collaborative Orchestra's inaugural season, as well as its future.

Yu traces SCOr's genesis to the day last winter when she came across YouTube videos featuring the Orpheus Chamber Orchestra: a New York-based, professional, conductorless ensemble dedicated to putting "democracy at the center of artistic execution." Hooked by the notion of a full orchestra that functions with the collegiality and distributed authority typical of a small chamber group, Yu wondered if the Orpheus model could be replicated at Stanford.

From the very beginning -- even in the audition process -- SCOr was different from a typical conductor-led orchestra. Auditionees were judged not just on their technical musicianship, but also on their ability to talk about their aesthetic choices.

"I played Haydn's D Major cello concerto," said Jeffrey Kwong of his own SCOr audition. After he'd played, "they asked me my thoughts about the piece and how I'd shaped it."

As Koo explained, "We asked them to explain their musical interpretation in the piece they'd played, and why they made those choices, in order to be sure they could clearly communicate their ideas."

SCOr's founders are adamant that communication is a crucial skill for all members of the ensemble. One of their goals was to create music that reflected the ideas, the experience and the artistic judgment of all the ensemble's members, not just the tastes of the conductor. For that to work, they needed players, in Yu's words, "who listen really well but also are not afraid to speak up."

Cellist Kwong agreed. "You want people who can listen to the opinions of others and integrate those ideas into the piece, but also people who can speak up" with their own suggestions. Through an ongoing dialogue at each rehearsal, he said, "we are able to use everyone's ideas and make something that is our own."

Of course, when everyone has a voice, there is a great deal more talking than in a conductor-led group. "We went in knowing it would be a much slower rehearsal process," said Koo. "But for us, it's a good exchange, because it lets everyone feel that they've contributed to the final piece."

Artistic interpretation is not the only aspect of the rehearsal process that's democratized. All the duties you would normally associate with an orchestra conductor are distributed among the players.

To maintain balance among the instruments, players take turns "sitting out" various portions of the rehearsal -- stepping away from the group and listening to ensure that all parts can be heard. Different members of the ensemble are chosen to set the tempo and give the downbeat for each movement or section of a work, generally determined by which instruments carry the dominant melody at that point.

As for keeping the players in sync, "Everyone has the responsibility to listen and be aware of the other musicians," said Koo. But also, "We play very physically, with our bodies." Rather than all eyes being fixed on the conductor's baton, the musicians watch the motion of each other's heads and shoulders and elbows. "We experimented during some rehearsals with setting up our chairs in concentric circles," Koo added. "It was very productive. It brought our attention to the center, brought everyone together as one organic machine."

SCOr's organizers even seek to democratize decisions about what the group should play. "Over the summer, we're using an online collaboration platform to choose next year's repertoire," Koo noted. "Our goal is that everyone will listen to lots of music," said Yu. "If they find something they think we could play, they'll add it to the list" for the rest of the players to hear and discuss.

Chris Costanza, an artist in residence with Stanford's music department who serves as SCOr's faculty advisor, has high praise for the students' commitment and growth over the course of the spring quarter. "Playing without a conductor, you learn to ... figure it out for yourselves," he said. "Players feel important and valued."

Costanza also noted that most of the members of SCOr are not music majors, but rather "super-talented musicians who love to play, and who commit to making music a part of their lives. They're very serious and excited about it."

Yu and Koo (a biologist and a computer science major, respectively) have similar praise for their fellow students who have joined them in this endeavor.

"I've been so impressed by the people who have joined us along the way," Yu said. "It's humbling that they have wanted to be part of this. The fact that people have been willing to set aside two and a half hours a week for rehearsal and to practice the music (on their own time) has been tremendous."

"Everyone is very dedicated. Everyone comes prepared," added Kwong. "This has been one of the most fantastic experiences I've had at Stanford -- being able to play with friends and make something that's yours from the beginning."

If SCOr's organizers have their way, the group will be part of the Stanford community for many years to come. Though there are no dates yet set for next season's performances, their hopes for the future include more concerts in larger campus venues, and they're working on a website to publicize the ensemble. Those who want to keep tabs on the group in the meantime can find the Stanford Collaborative Orchestra on Facebook.