Sirens evoke images of alarm, public service, war, and forthcoming air raid. Outside of the music of Edgard Varese, sirens have rarely been framed as musical instruments. By connecting air hoses to spinning disks with evenly-spaced perforations, the siren timbre is translated musically. Polyphony gives our instrument an organ-like personality: keys are mapped to different frequencies and the pressure applied to them determines volume. The siren organ can produce a large range of sounds both timbrally and dynamically. In addition to a siren timbre, the instrument produces similar sounds to a harmonica. Portability, robustness, and electronic stability are all areas for improvement.