What role does "tonality" play in music?

Tonality plays a crucial role in music by defining the key of a piece, which establishes a tonal center or “home” note around which the music is organized. This sense of a tonal center creates expectations for harmony and melody, guiding listeners' perceptions and experiences throughout a composition. When a piece of music resolves to the tonic or "home" chord, there is often a feeling of completeness or resolution, which is a fundamental aspect of tonal music.

In contrast, while loudness relates to dynamics and the volume of music, it does not pertain directly to the concept of tonality. Similarly, the arrangement of musical notes pertains more to the structure and composition of the piece rather than its tonal qualities. Lastly, the combination of sounds played simultaneously refers to harmony but does not define the tonal center, which is essential to understanding how tonality operates within a piece of music.