Final answer:
Playing large groups of adjacent notes on the piano creates a sound called a tone cluster, which is a dissonant musical chord.
Step-by-step explanation:
Playing large groups of adjacent notes on the piano in a percussive manner creates a sound known as a tone cluster. This term is used to describe a musical chord comprising at least three adjacent notes in a scale. The proximity of these notes creates a dissonant sound. Chordophones refer to a category of stringed instruments, aleatory refers to music where some element of the composition is left to chance, and gamelan is a traditional ensemble music of Java and Bali in Indonesia, made up predominantly of percussive instruments.