Rhythm (from Greek ῥυθμός – rhythmos, "any measured flow or movement, symmetry") is the variation of the length and accentuation of a series of sounds or other events.

Rhythm in linguistics

The study of rhythm, stress, and pitch in speech is called prosody; it is a topic in linguistics. Narmour (1980, p.147–53) describes three categories of prosodic rules which create rhythmic successions which are additive (same duration repeated), cumulative (short-long), or countercumulative (long-short). Cumulation is associated with closure or relaxation, countercumulation with openness or tension, while additive rhythms are open-ended and repetitive. Richard Middleton points out this method cannot account for syncopation and suggests the concept of transformation.

A rhythmic unit is a durational pattern which occupies a period of time equivalent to a pulse or pulses on an underlying metric level, as opposed to a rhythmic gesture which does not (DeLone et al. (Eds.), 1975

Origins of human appreciation of rhythm

In his series How Music Works, Howard Goodall presents theories that rhythm recalls how we walk and the heartbeat we heard in the womb. However neither would seem to have any survival value in Man's evolution. More likely is that a simple pulse or di-dah beat recalls the footsteps of another person. Our sympathetic urge to dance is designed to boost our energy levels in order to cope with someone, or some animal chasing us – a fight or flight response. It is possibly also rooted in courtship ritual.

Rhythm notation and the oral tradition

Worldwide there are many different approaches to passing on rhythmic phrases and patterns, as they exist in traditional music, from generation to generation.

African music

In the Griot tradition of Africa everything related to music has been passed on orally. Babatunde Olatunji (1927–2003), a Nigerian drummer who lived and worked in the United States, developed a simple series of spoken sounds for teaching the rhythms of the hand drum. He used six vocal sounds: Goon Doon Go Do Pa Ta. There are three basic sounds on the drum, but each can be played with either the left or the right hand. This simple system is now used worldwide particularly by Djembe players.

Indian music

Again an oral tradition. Tabla players would learn to speak complex rhythm patterns and phrases before attempting to play them. Sheila Chandra an English pop singer of Indian descent, made performances based around her singing these patterns. In Indian Classical music, the Tala of a composition is the rhythmic pattern over which the whole piece is structured.

Western music

Standard music notation contains all rhythmic information and is adapted specifically for drums and percussion instruments. The drums are generally used to keep other instruments in 'time'. They do this by supplying beats/strikes in time at a certain pace, i.e. 70 beats per minute (bpm). In Rock music, a drum beat is used to keep a bass/guitar line in time.