THE FRONTIER CAFÉ will host an evening of a capella fusion at 8 p.m. April 21. Zemya, a women’s a capella group that specializes in world music, and ImproVox, which focuses on American roots music and original songs, will perform. Both groups are from Maine. ImProVox is, clockwise from top, Martin Swinger, Deb Hensley, Fred White, Kathy Slack and Matt Loosigian. From 5:30 p.m. to 7 p.m., ImproVox will offer an improvisational singing workshop at Jai Yoga Studio upstairs from Frontier Cafe for singers at any skill level interested in exploring vocal improv and sharing their voices in an “instant choir” called a “Vortex.” Admission to the concert costs $12 in advance or $15 at the door. Contact Frontier Cafe at 725-5222 or visit online at www.explorefrontier.com for reservations. Contact Matt Loosigian at 891-9593 to reserve a place in the “Vortex.” Cost is $10.