How can harmony in music be best defined?

Harmony in music is best defined as the combination of different musical notes played or sung simultaneously. This concept is fundamental to the structure of music, as it provides depth and texture. When multiple notes are sounded together, they create chords, which can evoke various emotions and enhance the overall musical experience. Harmony often works alongside melody, giving a fuller sound and contributing to the overall atmosphere of a piece.

The other choices represent different musical concepts. Repetition of a single note refers to melody or ostinato, which is not related to harmony. The rhythmic pattern of a piece pertains to the tempo and timing, which are distinct from the idea of harmony. The speed of music, or tempo, is another different aspect that affects how music feels but does not encompass the definition of harmony. Thus, the correct answer integrates the essence of harmony effectively within the broader framework of music theory.