In March, the Seattle Symphony’s new Octave 9: Raisbeck Music Center opened with a bang: a 24-hour contemporary music marathon, with Seattle Symphony musicians and guest artists performing works by more than 50 composers, plus an immersive music installation. From March to June, the venue also offered free family open houses and interactive demonstrations of the space. The marathon began with the world premiere of an electronic piece by Melody Parker designed to showcase Octave 9’s sonic range and capabilities; among the composers featured during the marathon were John Luther Adams, Inti Logan Figgis-Vizueta, Jessie Montgomery, Gity Razaz, Alex Temple, and Julia Wolfe. The new space, located within Benaroya Hall, will host chamber concerts, performances, and conversations with artists and composers, and events for families. Features of Octave 9 include a surround-screen with moveable panels, projectors, motion-capture cameras, and an acoustic system with 42 speakers and 30 microphones.