Hemiola

In music, a hemiola is a rhythmic pattern in which two rhythms are superimposed. The most common type is the combination of three notes against two. Hemiolas tend to occur within a single beat, for example a piece in 4/4 time my have one part playing two quavers, and another three quaver triplets.

For pianists, playing mismatched rhythms requires a certain amount of mental detachment from what the hands are doing. Rhythmical expressions are sometimes used to help acquire the basic rhythm:

• 3 against 4: "cold cup of tea"
• 4 against 5: "what atrocious weather"