Syncopation puts the stress where your ear least expects it
Count a bar as one-and-two-and-three-and-four-and. Lean on the numbers and the rhythm sits squarely on the beat; lean on the ands and it starts to swing. That small shift of emphasis is syncopation, and it links a medieval English carol to Beethoven and the Rolling Stones.
Put simply, syncopation disturbs the regular flow of rhythm by accenting a weak beat or an off-beat instead of a strong one. Busy, complex-looking rhythms are not automatically syncopated; a dense pattern that keeps hitting the expected downbeats stays square. What matters is anything that shifts a listener's sense of where the strong beat falls, whether an accented note, a held note carried over a beat, a rest where a stress should be, or a note played a hair early or late. Harmony can do it too: a strong chord landing on a weak beat, as in many eighteenth-century cadences.
The musicologist Richard Middleton describes a syncopated pattern as a remapping of a plain one, heard in light of its straight partner. Satisfaction by the Rolling Stones shows the idea: the line I can't get no begins as a simple repeating long-short pattern, then a backbeat shift moves the stress onto I and can't, and a second nudge pushes can't and no ahead of the beat. Backbeat itself explains why some crowds clap on two and four while others clap on one and three. In Cuban son montuno, the bass habitually arrives just before the downbeat, a figure called the tumbao.
None of this began with pop. Fourteenth-century Italian and French composers used syncopation, and the refrain Deo gratias of the fifteenth-century Agincourt Carol bounces with it. Giovanni Gabrieli's off-beat accents in Venice were so characteristic that Denis Arnold called them almost a fingerprint, and Stravinsky admired his rhythmic inventions. Handel's Hornpipe from the Water Music of 1733 threads insistent off-beat stresses through running notes.
Beethoven made it dramatic. In the first movement of his Eroica Symphony he sets up three beats to a bar, then undermines them by pushing emphasis onto weak parts of the beat, hammering accents on weak beats and inserting silences where strong beats should fall. George Grove counted nine bars of loud discords placed on weak beats.
Source: Syncopation
