Watch Playing a Note on the Violin While I Walk Around in the Studio (1968) Official Trailer

In this film record of a studio activity, Nauman set himself the task of walking while playing "two notes [on a violin] very close together so that you could hear the beats in the harmonics." The camera is set centrally in the studio in a stationary position so that when he walks outside of the camera's view at times, only the sounds of the notes and footsteps are heard. Sound and image are out of sync, a situation noticeable only at the end of the film when the sound stops but Nauman continues to pace and play. [Overview Courtesy of Electronic Arts Intermix]