What term describes the rhythmic value of each note being shortened by half?

The term that accurately describes the rhythmic value of each note being shortened by half is called "diminution." Diminution involves taking a given rhythm and transforming it in such a way that each note's value is decreased, resulting in a more rapid note sequence. This technique can be observed in various forms of music, where original rhythms are embellished or altered to create a more intricate melodic line.

Understanding the concept of diminution is essential in music theory, particularly when analyzing compositions that employ intricate rhythmic patterns. It shows how composers can manipulate rhythm to add complexity and flair to their works.

The other terms have distinct meanings that do not correspond to the concept of shortening note values. For example, acceleration refers to an increase in tempo or speed, which contrasts with the idea of shortening note durations. Augmentation, on the other hand, involves lengthening the rhythmic values of notes, making it the opposite of diminution. Lastly, "rabato," typically refers to a flexible tempo or rhythmic freedom rather than a specific process of shortening note values. Understanding these distinctions helps solidify one’s grasp of rhythmic vocabulary in music theory.