Which term refers to the sound created when two or more notes are played simultaneously?

The term that refers to the sound created when two or more notes are played simultaneously is harmony. Harmony involves the combination of different musical notes played together to create a richer and more complex sound. It is a fundamental aspect of music that supports melody by providing a backdrop or context, allowing melodies to develop within a fuller auditory environment.

Interval refers to the distance between two notes, not their simultaneous sound. Imitation describes the repetition of a musical phrase in a different voice or part, often seen in contrapuntal music. Inversion typically refers to the rearrangement of the notes in a chord or scale, altering the bass note, rather than the simultaneous sound of different notes. Thus, the concept of harmony distinctly encompasses the essence of multiple notes played at once.