A hemiola (from the Greek — “one and a half”) is an expressive rhythmic device based on the ratio 3:2. Most often it arises when two bars of triple meter (for example, 3/4) are momentarily perceived as three bars of duple (2/4) — the accents shift, and the listener feels an unexpected “knocking off” of the usual pulse.
The hemiola creates an effect of springiness, play, and rhythmic flexibility. It was widely used already in the Baroque era, especially at the ends of phrases and before cadences, and it is also a natural feature of many folk dances — Spanish, Latin American, and Slavic, being characteristic of Ukrainian dance music among them. A celebrated example of hemiola in art music is the song “America” from the musical “West Side Story” by Leonard Bernstein.
