Hemiola
Reinterpretation of two triple-time bars as three groups of two.
What it means
The hemiola, Greek for “one and a half,” is the rhythmic reinterpretation of two triple-time bars as three groups of two. Two bars in 3/4 time that would be counted 1-2-3, 1-2-3 become three groups of two beats each: 1-2, 1-2, 1-2. The ratio of three to two produces brief rhythmic tension although the beat stays the same.
Musical use
The hemiola is a favorite means of stressing closes and cadences, especially in the Baroque and Viennese Classical periods, for instance at the end of a minuet. The last two bars are stressed as if they stood in a different metre, which strengthens the closing effect. In the 19th and 20th centuries composers also used the hemiola as a basic principle, for instance Johannes Brahms in his symphonies and Leonard Bernstein in “America” from West Side Story, where 6/8 and 3/4 alternate.
The hemiola should be distinguished from syncopation, which shifts stresses against the metre, and from polyrhythm, in which several rhythms sound at once. In the hemiola the rhythms replace each other instead of overlapping.
Performance practice
Feel the new grouping in a hemiola by tapping the stressed beats or counting aloud. Keep the basic tempo unchanged and stress the new emphases clearly but not hard, so the effect is audible as a brief change of rhythm.