Catherine Lamb and Rebecca Lane Credit: Courtesy of Catherine Lamb

A secondary rainbow is a faint visual echo that appears outside a rainbow when light bends twice while passing through raindrops. Composer, violist, and occasional vocalist Catherine Lamb uses careful calculation and subtle dynamics to evoke correspondingly liminal sonic experiences. Born in Olympia, Washington, and based in Berlin, she’s developed a musical approach that combines elements drawn from her formal studies with composers such as James Tenney and Michael Pisaro at CalArts and Bard with lessons she’s learned through one-on-one engagements with late filmmaker Mani Kaul (also a musician in the Indian classical tradition of dhrupad) and French electronic composer Éliane Radigue. Her compositions for solo performance, small ensembles, and orchestras sometimes use the alternate tuning system known as just intonation as well as environmental input to create music that spotlights subtle tonal interactions, such as the “beats” created by the interference between two pure tones close in pitch when they’re sounded together. Like Radigue, Lamb often makes extremely quiet music, so that the act of close listening becomes part of the experience of the piece. Prisma Interius IV, the piece that Lamb will perform here with Australian flutist and fellow Berliner Rebecca Lane, is one of a nine-part series that uses what she’s christened the “secondary rainbow synthesizer,” an instrument she’s developing with experimental musician Bryan Eubanks. It consists of a system of live microphones feeding into software that filters certain bandwidths, to draw selected aspects of the sonic environment into the performance. It’s possible to hear how this operates on Prisma Interius VI, which is on a double album called Viola Torros (Another Timbre) that Lamb made with fellow violist Johnny Chang. Outside sounds seep into the music, and slowly shift from unmodified traffic and pedestrian noises into a halo of resonance that casts a fluctuating glow onto the strings’ slow-arcing melodies. For this performance, Chicagoan Olivia Block will operate the secondary rainbow synthesizer.   v