Boston has many choirs--from the a cappella groups of our various colleges and universities to the professional niche choruses such as Voices Rising and the Cantata Singers, to large acts such as the Boston Gay Men's Chorus. Talented and wonderful as the aforementioned are, none is as singular and innovative as the Boston Secession.

Started in 1996 as a "laboratory for modernizing professional vocal performance" by artistic director and conductor Jane Ring Frank, the Boston Secession was named for artist Gustav Klimt's co-operative, the Vienna Secession, which "created a sensation by displaying paintings at eye level for the first time." Frank hoped to bring something similar to vocal music that would draw people in.

Judging by their recent performance of "Altered States: Mysticism in Music," Frank's vision is bearing ripe fruit. Boston Magazine referred to the chorus glowingly, credited Secession with "revitalizing the concert experience." These are not empty words.

The chorus performed "Altered States" at the First Church in Cambridge, outside Harvard Square. The cross-shaped sanctuary provides a suitable reverential space, which also happens to have acoustics perfect for soloist Mary Sullivan's soaring, angelic soprano. Highlights of the show included such diverse music as Benjamin Britten's "Rejoice in the Lamb"; the 12th-century nun Hildegard von Bingen's chant "Rapture" sung to an arrangement of the Beatles' "Let It Be"; the sonic meditation "Get Your Rocks Off" by Pauline Oliveros, in which the singers circle the audience, bang rocks and speak pre-assigned and spontaneous words, as well as works by Orlando di Lasso, George Crumb and others. Boston Secession is known for its creativity and exactness. Both were in full force this night: every note, every line, every bang of a rock was perfect.

Listeners of National Public Radio and Somerville residents got an additional treat: the show was narrated by Ellen Kushner, one-time local author and host of NPR's "Sound and Spirit." Kushner's joie-de-vivre and ironic wit made a lovely counterpoint.

The chorus released its first CD entitled Afterlife: German Choral Meditations on Mortality in 2005, on local label Brave Records (www.braverecords.com.) They're currently at work on their second CD, which is due out in 2007.

Fans of choral or experimental music should not wait to hear the Boston Secession. Their season runs from November to April. Upcoming shows include "(Un)Lucky in Love" on Friday, February 2, 2007, "Surprised by Beauty: Minimalism in Choral Music" on Friday, March 16," and "Mother Tongue: The Music and Meter of the English Language" on Friday April 17. Another fan favorite that is not on this year's schedule but bears repeating is the Secession's version of Jean Cocteau's black-and-white foreign masterpiece, "Orfeo" (Orpheus.) The choir scores the film, occasionally even replacing the dialogue. Superb.

Tickets for upcoming shows, season tickets, and CDs are available for sale on the Chorus' Web-site: www.bostonsecession.org.