What is the term for a rhythmic change from groups of three beats to groups of two beats?

The term describing a rhythmic change from groups of three beats to groups of two beats is known as hemiola. In musical contexts, hemiola often creates a feeling of tension or a shift in rhythm, as it juxtaposes two different metrical groupings. For instance, while a piece may predominantly be in triple meter (like a waltz), introducing a section that feels like it is in duple meter can create a compelling contrast. This rhythmic interplay highlights the flexibility of meter and emphasizes moments within the music when the listener can feel a shift or a new layer of complexity.

The concept of hemiola is often employed in various genres and can be particularly effective in creating rhythmic excitement, especially in classical and contemporary music. This change makes the rhythm feel lively or syncopated, enhancing the overall musical experience. Understanding hemiola allows musicians and listeners alike to appreciate the subtleties of rhythm in compositions.