Go ahead and clap your hands as the East Metro Symphony Orchestra plays. Feel free to sing along, too.
Orchestra purists might shudder at the notion, but conductor Elizabeth Prielozny Barnes is encouraging the behavior Sunday when the 50-member symphony teams with a cappella barbershop-style Twin Cities Show Chorus for the Festival of American Original Song at East Ridge High School's Loft Stage.
"That is not normally what would you do at an orchestra concert, but we encourage the audience to personally engage and make music," Prielozny Barnes said. "Orchestras have this reputation of having a secret code of behavior, like it's OK to talk here or clap here but not there. We are informal."
Formerly known as the 3M Club Symphony Orchestra, the all-volunteer ensemble also is adventurous. In March, the symphony will present a program of Indonesian music and dance.
On Sunday, the orchestra will provide the accompaniment as the award-winning chorus leads the audience in a medley of toe-tapping numbers from Meredith Willson's "The Music Man" to the grand finale, "The Battle Hymn of the Republic."
"We don't do things just to be different," Prielozny Barnes said. "We do things that sound interesting, are enlightening collaborations and bring musical experiences to our audience that they normally would not see."
The program will be a "whole new thing" for the 65-member Twin Cities Show Chorus, said the group's business manager, Wendy Hamilton. For starters, the choir will stand on risers behind the orchestra instead of being front and center. And while there will still be the customary four- and eight-part harmony, there won't be as much improvisation as usual.
"As an a cappella group, we like to embellish the ballad chords or change the tempo if we want," Hamilton said. "We are used to being in charge. This is totally different. Our director spent two months matching up every score and every line."
Rehearsals were different, too. The chorus practiced its set by using a videotape of the orchestra.
Directed by Judy Olson, the Twin Cities Show Chorus is a member of the Sweet Adelines, and was the Region 6 Chorus champions in 2010. The 65-member chorus' proudest moment might have come in 1996, when it was named the gold medalist at the International Music Festival in Sydney, Australia. Hamilton said members are excited to sing with an orchestra, new in the chorus' 36-year history.
"It's going to be fabulous," Hamilton said. "We are looking forward to having a good time."
Tim Harlow • 651-925-5039, Twitter: @timstrib