Filmmaker Mike McSweeney introduces us to a most unusual orchestra, the configuration of which changes constantly, day after day, night after night: the large population of street musicians whose sounds and tunes inhabit the aural spaces of the New York City subway system. Metro users come and go, often paying no attention, yet these musicians have become an indelible part of this underground landscape. Sound Underground unfolds as a ballad without words, giving voice to the most diverse musics and their musicians: a saxophonist warming up on a platform, a percussionist playing to “spread joy,” the vibes of “Für Elise” on a steel drum, a musical saw resonating uncannily in the hallways of Grand Central–42ndStreet Station. In this vibrant compilation of sounds and images, music beats to the pulses and rhythms of the subway trains.  JW