Polyrhythm
Polyrhythm is the simultaneous sounding of two or more independent
rhythms. Polyrhythms are distinguished from
irrational rhythms, which can occur within the context of a single part, whereas polyrhythms require at least two rhythms to be played concurrently.
A simple example of a polyrhythm is 3 evenly-spaced notes against 2, with the 3-beat pattern being faster than the 2-beat pattern, so that they both take the same amount of time (see
sesquialtera). Other simple polyrhythms are 3:4, 4:3, 5:4, 7:4, etc.
Another form of polyrhythm, which might also be termed
polymeter, would be phrasing to suggest a different meter than the one being played by the rest of the ensemble. A common example of this in
jazz would be phrasing quarter notes in groupings of 3 to suggest 3/4 time while the ensemble plays in 4/4. Compare with
hemiola (not a polyrhythm).
Traditional
African music, particularly that of
West Africa, is known for its highly complex polyrhythms and, unlike the examples given below, the downbeats do not usually coincide. Traditional West African is considered by musicologists to be the most rythmically complex music in the world. Rhythms and counter rhythms evidence the common African tradition of
call and response, with different drum lines, other musical instruments, bodies and voices contributing rhythmic elements that complement and communicate with one another. This element of instrumental, as well as vocalized, call and response is also evident in the polyrhythmic quality of jazz. By contrast, traditional European music has a flat linearity.
Nigerian percussion master
Babatunde Olatunji exploded on the American music scene in 1959 with his album
Drums of Passion, which was a collection of traditional Nigerian music for percussion and chanting. The album stayed on the charts for two years and had a profound impact on jazz and American popular music. Trained in the
Yoruba sakara style of drumming, Olatunji would go on to teach, collaborate and record with numerous jazz and rock artists, including
Airto Moreira,
Carlos Santana and
Mickey Hart of the
Grateful Dead. He reached his greatest popularity during the height of the Black Arts Movement of the 1960s and '70s. An
Afro-Cuban conguero, or
conga player,
Mongo Santamaria was another percussionist whose polyrhythmic virtuosity helped transform both jazz and popular music. Santamaria fused Afro-Latin rhythms with
R&B and jazz as a bandleader in the 1950s, and was featured in the 1994
Buena Vista Social Club album, which was the inspiration for the like-titled documentary released five years later.
Frank Zappa, especially towards the end of his career, experimented a lot with complex polyrhythms, such as 11:17, and even nested polyrhythms. The
metal band
Meshuggah also uses polyrhythms in their music, almost exclusively in fact, although their quirkiness is mostly of a polymetric nature. Contemporary progressive metal bands such as
Tool and
Portal also incorporate polyrhythms in their music. Much
minimalist and
totalist music makes extensive use of polyrhythms.
Henry Cowell and
Conlon Nancarrow created music with yet more complex polytempo and using irrational numbers like
pi:
e.
Common polyrhythms found in jazz are 3:2, which manifests as the quarter-note triplet; 2:3, usually in the form of dotted-quarter notes against quarter notes; 4:3, played as dotted-eight notes against quarter notes (this one demands some technical proficiency to perform accurately, and was not at all common in jazz before
Tony Williams used it when playing with
Miles Davis); and finally 3/4 time against 4/4, which along with 2:3 was used famously by
Elvin Jones and
McCoy Tyner playing with
John Coltrane.
Cuban music makes extensive use of polyrhythms. Cuban
Rumba uses 3-based and 2-based rhythms at the same time, for example, the lead drummer (playing the
quinto) might play in 6/8, while the rest of the ensemble keeps playing 2/2.
The following is an example of a 2 against 3 polyrhythm, given in
time unit box system (TUBS) notation; each box represents a fixed unit of time; time progresses from the left of the diagram to the right, although this is irrelevant since the pattern is symmetric. Beats are indicated with an X; rests are indicated with a blank.
2 against 3 polyrhythm | 3-beat rhythm | X | | X | | X | | X | | X | | X | | X | | X | | X | | X | | X | | X | |
| 2-beat rhythm | X | | | X | | | X | | | X | | | X | | | X | | | X | | | X | | |
A common memory aid to help with the 2 against 3 polyrhythm is that it has the same rhythm as the phrase "not difficult"; the simultaneous beats occur on the word "not"; the second and third of the triple beat land on "dif" and "cult", respectively. The second 2-beat lands on the "fi" in "difficult." Try saying "not difficult" over and over in time with the sound file below. Another phrase with the same rhythm is "cold cup of tea":
|
Music_cross-rhythm,_cold_cup_of_tea.PNG |
Similar phrases for the 3 against 4 polyrhythm are "pass the gold-en but-ter" and "what atrocious weather"; The 3 against 4 polyrhythm is shown below.
3 against 4 polyrhythm | 4-beat rhythm | X | | | X | | | X | | | X | | | X | | | X | | | X | | | X | | |
| 3-beat rhythm | X | | | | X | | | | X | | | | X | | | | X | | | | X | | | |
|
Music_cross-rhythm,_what_atrocious_weather.PNG |
As can be seen from above, the counting for polyrhythms is determined by the
lowest common multiple, so if one wishes to count 2 against 3, one needs to count a total of 6 beats, as lcm(2,3) = 6 (
12
34
56 and
123
456). However this is only useful for very simple or polyrhythms, or for getting a feel for more complex ones, as the total number of beats rises quickly. To count 4 against 5, for example, requires a total of 20 beats, and counting thus slows the tempo considerably. However some players, such as
classical Indian musicians, can intuitively play high polyrhythms such as 7 against 8.
Below are some example polyrhythms in
MIDI format:
*
2 against 3 polyrhythm in MIDI format*
3 against 4 polyrhythm in MIDI format*
Ewe music*
African Music Encyclopedia: Babatunde Olatunji*
"Africano, the mother of groove," an article on polyrhythms and the African drumming tradition*
Tempo Mental- Article by Steve Vai on Polyrhythms
*
Drums Database- More Polyrhythms
*
polyPulse An athenaCL netTool for on-line, web-based MIDI polyrhythm generation
*
polymath Another on-line, web-based MIDI polyrhythm generation tool which uses symbolic input
