Brazilian artist Carlito Carvalhosa (b. 1961) conceived Sum of Days as an environmental and participatory sound installation—a monumental, voluminous construction made of soft, white, translucent material that hangs from ceiling to floor and takes the shape of an elliptical labyrinth. This structure hides, or interrupts, the defined limits of its surrounding architectural space, suspending visitors' spatial references and allowing an experience of total immersion. A system of microphones hangs from various heights and records the day's ambient noise, which is played back the following day through several speakers. Each day a new recording is superimposed over the previous one, gradually dimming the oldest sounds into a layer of whispers. Adding yet another element of sound will be periodic musical performances from within the installation. The accumulation of these recordings will constitute an immaterial layering of time—an auditory memory of the accidental noise inherent in everyday experience. This marks the artist’s first exhibition in the United States.

Musical performances, each 60 to 90 minutes long, take place weekly within the installation between September 8 and November 10. The performers are Lisa Bielawa, David Crowell, Jon Gibson, Philip Glass, Carla Kihlstedt, Michael Riesman, Mick Rossi, and Andrew Sterman. Times are announced via MoMA’s Twitter account (@MuseumModernArt) on the day of the event.