“Granular Graph” is an audio-visual interactive instrument about musical gesture and its notation. The idea is inspired by a pendulum-based scientific instrument called Harmonograph. In its simplest version, two pendulums are suspended through holes in a table. The swinging pendulums cause an attached pen to move, thus creating a curvaceous geometric image on paper that represents harmonies and intervals in musical scales. “Graph” not only re-appropriates the idea of a mechanism by inviting audiences to form a living pendulum through playing on swings, but uses water function as paper, to graph the amount of energy, effort and tension involved in causing the sounds. Any visitor can play the instrument by sitting or standing on one of two swings. The resulting pendular movements alter the waterflow in a tank, generating not only a vibrating pattern but also sounds. The sounds and images can be regarded as forms of dynamic notation that graphically and kinetically represent the audience’s gesture and energy expenditure.