The Bowed Piano Ensemble is best observed from a sky-cam. The group consists of ten musicians who are affiliated with Colorado College in Colorado Springs; they're under the command of Stephen Scott, an instructor at the school who's internationally renowned not only for his intriguing modern-classical compositions but also for the manner in which they're brought to life -- by collaborators who physically pluck, caress or stroke the strings of an open piano. Describing the process can make Scott's methodology seem like a stunt, but the sound itself is extraordinarily rich and complex, as if an entire orchestra is lurking inside of a single instrument. The act's two performances this week -- 2 p.m. and 4 p.m. Saturday, April 28 -- are benefits for the Pioneers Museum, 215 South Tejon Street in Colorado Springs, where the shows will take place; they are scheduled to include the world premiere of Scott's "Vocalise on 'In a Silent Way,'" featuring soprano Victoria Hansen Clamp, as well as renditions of such Scott staples as "Vikings of the Sunrise." Your eyes won't believe what your ears are hearing.