What does augmentation entail in music?

Augmentation in music refers to the process of increasing the note values of a musical theme. This technique is often used in compositional practices to create variations of a theme, making it sound slower and more expansive while retaining its original contour and rhythm. For example, if the original theme consists of quarter notes, augmentation might transform those into half notes, effectively doubling the note durations. This not only alters the rhythmic feel but also can emphasize the melodic aspects of the theme, allowing it to be perceived in a new light.

The other potential answers involve different musical concepts. Changing the tempo refers to how fast or slow a piece is played, which is distinct from note value adjustments. Modifying the key pertains to shifting the entire piece to a different tonal center, impacting the pitch but not the rhythmic structure or the lengths of notes. Adding additional instruments is a matter of orchestration or arrangement, focusing on texture rather than the rhythmic alteration that augmentation entails. Thus, the correct understanding of augmentation is primarily linked to the alteration of note durations rather than these other musical elements.