View source for Cross-beat

{{short description|Specific form of polyrhythm}}
{{hatnote|This article is about music. For the use in horology, see [[Cross-beat escapement]]. For cross-beat tonguing, see [[Tonguing]]. "Cross-rhythm" redirects here. For the Christian media organization, see [[Cross Rhythms]]}}

In [[music]], a '''cross-beat''' or '''cross-rhythm''' is a specific form of [[polyrhythm]]. The term ''cross rhythm '' was introduced in 1934 by the [[Musicology|musicologist]] [[Arthur Morris Jones]] (1889–1980). It refers to a situation where
the rhythmic conflict found in polyrhythms is the basis of an entire musical piece.<ref>''New Harvard Dictionary of Music'' (1986: 216). Cambridge, MA: Harvard University Press.</ref>

== Etymology ==
The term "cross rhythm" was introduced in 1934 by the [[Musicology|musicologist]] [[Arthur Morris Jones]] (1889–1980), who, with [[Klaus Wachsmann]], took-up extended residence in [[Zambia]] and [[Uganda]], respectively, as [[missionaries]], educators, [[musicologists]], and [[museologists]].

{{cquote|'''Cross-rhythm'''. A rhythm in which the regular pattern of accents of the prevailing meter is contradicted by a conflicting pattern and not merely a momentary displacement that leaves the prevailing meter fundamentally unchallenged.|25px|25px|[[Harvard Dictionary of Music|The New Harvard Dictionary of Music]] (1986: 216)<ref name="New Harvard 1986">''[[Harvard Dictionary of Music|The New Harvard Dictionary of Music]],'' [[Don Michael Randel]] (ed.), [[Belknap Press]], [[Harvard University Press]] (1986), pg. 216; {{oclc|13333674}}</ref>}}

== African music ==

=== One main system ===
[[File:Niger-Congo-en.svg|thumb|right|180px|Niger-Congo linguistic group (yellow and yellow-green).]]

African cross-rhythm is most prevalent within the greater Niger-Congo linguistic group, which dominates the continent south of the Sahara Desert. (Kubik, p.&nbsp;58)<ref name="Kubik 1999" /> Cross-rhythm was first identified as the basis of sub-Saharan rhythm by A.M. Jones. Later, the concept was more fully explained in the lectures of [[Ewe drumming|Ewe]] master drummer and scholar C.K. Ladzekpo, and in the writings of David Locke.<ref name="Locke 1982" /> Jones observes that the shared rhythmic principles of Sub-Saharan African music traditions constitute ''one main system''.<ref name="Jones 1959" /> Similarly, Ladzekpo affirms the ''profound homogeneity'' of sub-Saharan African rhythmic principles.<ref name="Ladzekpo 1995" /> In [[Sub-Saharan African music traditions]] (and many of the [[African diaspora|diaspora]] musics) cross-rhythm is the generating principle; the meter is in a permanent state of contradiction.

=== An embodiment of the people ===
{{cquote|At the center of a core of rhythmic traditions and composition is the technique of cross-rhythm. The technique of cross-rhythm is a simultaneous use of contrasting rhythmic patterns within the same scheme of accents or meter ... By the very nature of the desired resultant rhythm, the main beat scheme cannot be separated from the secondary beat scheme. It is the interplay of the two elements that produces the cross-rhythmic texture.|25px|25px|Ladzekpo, a: "Myth"<ref name="Ladzekpo 1995" />}}

{{cquote|From the philosophical perspective of the African musician, cross-beats can symbolize the challenging moments or emotional stress we all encounter. Playing cross-beats while fully grounded in the main beats, prepares one for maintaining a life-purpose while dealing with life’s challenges. Many sub-Saharan languages do not have a word for ''rhythm'', or even ''music''. From the African viewpoint, the rhythms represent the very fabric of life itself; they are an embodiment of the people, symbolizing interdependence in human relationships.|25px|25px|''Clave Matrix'', p. 21<ref name="Peñalosa 2009" />}}

== Cross-rhythmic ratios ==

=== 3:2 ===
The cross-rhythmic [[ratio]] ''three-over-two'' (3:2) or vertical [[hemiola]], is the most significant rhythmic [[cell (music)|cell]] found in sub-Saharan rhythms. The following measure is evenly divided by three beats and two beats. The two [[cycle (music)|cycles]] do not share equal status though. The two bottom notes are the primary beats, the ground, the main temporal referent. The three notes above are the secondary beats. Typically, the dancer's feet mark the primary beats, while the secondary beats are accented musically.[[File:Polyrhythm3c2.theora.ogv|thumb|Polyrhythm 3:2]]

{{multiple image
 | align   = center
 | width   = 200
 | image1  = 3 over 2.png
 | caption1=Additive
 | image2  = 3 over 2.-Bmus.png
 | caption2=Divisive
 | footer  = Three-over-two cross-rhythm {{audio|3 over 2.mid|Play}}
}}

{{YouTube|id=c6LEW9W0HDU|title=Watch: Stepping to the main beats within 3:2 cross-rhythm. Afro-Cuban "Obatalá Dance" (Marta Ruiz)}}

{{cquote|We have to grasp the fact that if from childhood you are brought up to regard beating 3 against 2 as being just as normal as beating in synchrony, then you develop a two dimensional attitude to rhythm... This bi-podal conception is... part of the African's nature|25px|25px|Jones (1959: 102)<ref name="Jones 1959" />}}

Novotney observes: "The 3:2 relationship (and [its] permutations) is the foundation of most typical polyrhythmic textures found in West African musics."<ref>Novotney, Eugene D. (1998). ''The Three Against Two Relationship as the Foundation of Timelines in West African Musics'' Urbana, IL: University of Illinois. UnlockingClave.com.</ref> 3:2 is the ''generative'' or ''theoretic form'' of sub-Saharan rhythmic principles. [[Victor Kofi Agawu|Agawu]] succinctly states: "[The] resultant [3:2] rhythm holds the key to understanding ... there is no independence here, because 2 and 3 belong to a single Gestalt."<ref>Agawu, Kofi (2003: 92). ''Representing African Music: Postcolonial Notes, Queries, Positions New York: Routledge''. {{ISBN|0-415-94390-6}}.</ref>

'''African [[Xylophone]]s''' such as the [[balafon]] and [[gyil]] play cross-rhythms, which are often the basis of [[ostinato]] melodies. In the following example, a Ghanaian [[gyil]] sounds the three-against-two cross-rhythm. The left hand (lower notes) sounds the two main beats, while the right hand (upper notes) sounds the three cross-beats. ''(Clave Matrix'' p.&nbsp;22)<ref name="Peñalosa 2009" />
[[File:Gyil.JPG|thumb|right|210px|Ghanaian gyil]]
[[File:Ghanaian gyil.jpg|thumb|center|300px|Ghanaian gyil sounds 3:2 cross-rhythm. {{audio|Ghanaian gyil.mid|Play}}]]

=== 6:4 ===
'''The primary cycle of four beats'''[[File:Polyrhythm6c4.theora.ogv|thumb|Polyrhythm 6:4]]

A great deal of African music is built upon a [[Cycle (music)|cycle]] of four main beats. This basic [[Period (music)|musical period]] has a bipartite structure; it is made up of two [[cell (music)|cells]], consisting of two beats each. Ladzekpo states: "The first most useful measure scheme consists of four main beats with each main beat measuring off three equal pulsations [{{Time signature|12|8}}] as its distinctive feature ... The next most useful measure scheme consists of four main beats with each main beat flavored by measuring off four equal pulsations [{{Time signature|4|4}}]." (b: "Main Beat Schemes")<ref name="Ladzekpo 1995" /> The four-beat cycle is a shorter period than what is normally heard in European music. This accounts for the stereotype of African music as "repetitive." (Kubik, p.&nbsp;41)<ref name="Kubik 1999" /> A cycle of only two main beats, as in the case of 3:2, does not constitute a complete primary cycle. (Kubik, Vol. 2, p.&nbsp;63)<ref name="Kubik 1999" /> Within the primary cycle there are two cells of 3:2, or, a single cycle of six-against-four (6:4). The six cross-beats are represented below as quarter-notes for visual emphasis.

[[File:Six against four cross-rhythm represented as six quarter notes of four dotted quarter notes.jpg|thumb|center|300px|Six-against-four cross-rhythm (note that this is identical to the three-over-two cross-rhythm above, played twice).]]

{{cquote|Interacting the four recurrent triple structure main beat schemes (four beat scheme) simultaneously with the six recurrent two pulse beat schemes (six beat scheme) produces the first most useful cross rhythmic texture in the development of [[Ewe drumming|Anlo-Ewe]] dance-drumming.|25px|25px|Ladzekpo (c: "Six Against Four")<ref name="Ladzekpo 1995" />}}

The following notated example is from the [[kushaura]] part of the traditional mbira piece "Nhema Mussasa." The left hand plays the [[ostinato]] "bass line," built upon the four main beats, while the right hand plays the upper melody, consisting of six cross-beats. The composite melody is an embellishment of the 6:4 cross-rhythm. ''(Clave Matrix'' p.&nbsp;35)<ref name="Peñalosa 2009" />

[[File:Holding an mbira dzavadzimu.jpg|thumb|left|180px|Holding an mbira dzavadzimu.]]

=== 3:4 ===
[[File:Polyrhythm4c3.theora.ogv|thumb|Polyrhythm 3:4]] If every other cross-beat is sounded, the three-against-four (3:4) cross-rhythm is generated. The "slow" cycle of three beats is more metrically destabilizing and dynamic than the six beats. The Afro-Cuban rhythm [[abakuá]] (Havana-style) is based on the 3:4 cross-rhythm.<ref name="Coburg 2004" /> The three-beat cycle is represented as half-notes in the following example for visual emphasis.

[[File:3-4 cross rhythm.jpg|thumb|center|300px|Three-against-four cross-rhythm. {{audio|3 over 4.mid|Play}}]]

{{cquote|In contrast to the four main beat scheme, the rhythmic motion of the three beat scheme is slower. A simultaneous interaction of these two beat schemes with contrasting rhythmic motions produces the next most useful cross rhythmic texture in the development of sub-Saharan dance-drumming. The composite texture of the three-against-four cross rhythm produces a motif covering a length of the [[Period (music)|musical period]]. The motif begins with the component beat schemes coinciding and continues with the beat schemes in alternate motions thus showing a progression from a "static" beginning to a "dynamic" continuation|25px|25px|Ladzekpo ("Three Against Four")<ref name="Ladzekpo 1995" />}}

The following pattern is an embellishment of the three-beat cycle, commonly heard in African music. It consists of three sets of three strokes each.

=== 1.5:4 (or 3:8) ===
[[File:Polyrhythm-1.5 with 4 o 4 simultaneously.ogv|thumb|Polyrhythm 4:1.5]] Even more metrically destabilizing and dynamic than 3:4, is the ''one and a half beat-against-four'' (1.5:4) cross-rhythm. Another way to think of it is as three "very slow" cross-beats spanning two main beat [[cycle (music)|cycles]] (of four beats each), or three beats over two [[period (music)|periods]] ([[Bar (music)|measures]]), a type of macro "[[hemiola]]." In terms of the beat scheme comprising the complete 24-pulse cross-rhythm, the [[ratio]] is 3:8. The three cross-beats are shown as whole notes below for visual emphasis.

[[File:3 over 8.tif|thumb|center|400px|1.5:4 or 3:8. {{audio|3 over 8.mid|Play}}]]

The 1.5:4 cross-rhythm is the basis for the open tone pattern of the enú (large [[batá]] drum head) for the [[Afro-Cuban]] rhythm changó ([[Shango]]).<ref name="Aña_Jiménez-Rhythms 1994" group=lower-alpha /> It is the same pattern as the previous figure, but the strokes occur at half the rate.

[[File:1.5 cross-beats per four main beats.tif|thumb|center|400px|Drum pattern based on 1.5:4 cross-rhythm ({{audio|1.5 cross-beats per four main beats.mid|Play}}).]]
[[File:Africanagogo.jpg|thumb|right|95px| [[Ewe music|Ewe]] [[gankoqui]] bell]]
The following [[bell pattern]] is used in the [[Ewe drumming|Ewe]] rhythm kadodo.<ref>"Kadodo," ''Ritual Music of the Yeve'', (Ladzekpo brothers). Makossa phonorecord 86011 (1982).</ref> The pattern consists of three modules—two pairs of strokes, and a single stroke. The three single stroke are muted. The pattern is another embellishment of the 1.5:4 cross-rhythm.

[[File:Kadodo bell pattern.tif|thumb|center|400px|kadodo bell pattern ({{audio|Kadodo bell pattern.mid|Play}})]]

=== 4:3 ===
When duple pulses ({{Time signature|4|4}}) are grouped in sets of three, the four-against-three (4:3) cross-rhythm is generated. The four cross-beats cycle every three main beats. In terms of cross-rhythm only, this is the same as having duple cross-beats in a triple beat scheme, such as {{Time signature|3|4}} or {{Time signature|6|4}}. The pulses on the top line are grouped in threes for visual emphasis.

[[File:Four against three in modular form.jpg|thumb|center|320px|4:3 cross-rhythm in modular form.]]

However, this 4:3 is within a duple beat scheme, with duple (quadruple) subdivisions of the beats. Since the [[period (music)|musical period]] is a [[cycle (music)|cycle]] of four main beats, the 4:3 cross-rhythm significantly contradicts the period by cycling every three main beats. The complete cross-beat cycle is shown below in relation to the [[bell pattern|key pattern]] known in Afro-Cuban music as [[clave rhythm|clave]]. ''(Rumba,'' p. xxxi)<ref name="Peñalosa 2010" /> The subdivisions are grouped (beamed) in sets of four to reflect the proper metric structure. The complete cross-beat cycle is three claves in length. Within the context of the complete cross-rhythm, there is a macro 4:3—four ''4:3 modules''-against-three ''claves''. Continuous duple-pulse cross-beats are often sounded by the [[quinto (drum)|quinto]], the lead drum in the Cuban genres [[Cuban rumba|rumba]] and [[Conga (music)|conga]]. ''(Rumba,'' pps. 69–86)<ref name="Peñalosa 2010" /><ref name="Muñequitos=Beodos 1956 v. 2" group=lower-alpha /><ref name="Muñequitos=Beodos 1956 v. 1" group=lower-alpha />
[[File:Quinto drum.JPG|thumb|left|160px|Quinto drum]]
[[File:4 against 3 cross-rhythm.jpg|thumb|center|360px|Complete cycle of 4:3 cross-rhythm shown in relation to [[clave (rhythm)|clave]].]]

{{cquote|While 3:2 pervades ternary music, quaternary music seldom uses tuplets; instead,
a set of dotted notes may temporarily make 2:3 and 4:3 temporal structures.|25px|25px|Locke ("Metric Matric")<ref name="Locke 2011" />}}

== Duple-pulse correlative of 3:2 ==
In sub-Saharan rhythm the four main beats are typically divided into three or four pulses, creating a 12-pulse ({{Time signature|12|8}}), or 16-pulse ({{Time signature|4|4}}) [[cycle (music)|cycle]]. (Ladzekpo, b: "Main Beat Scheme")<ref name="Ladzekpo 1995" /> Every triple-pulse pattern has its duple-pulse correlative; the two pulse structures are two sides of the same coin. Cross-beats are generated by grouping pulses contrary to their given structure, for example: groups of two or four in {{Time signature|12|8}} or groups of three or six in {{Time signature|4|4}}. ''(Rumba,'' p.&nbsp;180)<ref name="Peñalosa 2010" /> The duple-pulse correlative of the three cross-beats of the [[hemiola]], is a figure known in Afro-Cuban music as [[tresillo (rhythm)|tresillo]]. Tresillo is a [[Spanish language|Spanish]] word meaning ‘[[tuplet|triplet]]’—three equal notes within the same time span normally occupied by two notes. As used in Cuban popular music, tresillo refers to the most basic duple-pulse rhythmic [[cell (music)|cell]].<ref>Mauleón, Rebeca (1993: 51). ''Salsa Guidebook for Piano and Ensemble''. Petaluma, California: Sher Music. {{ISBN|0-9614701-9-4}}.</ref> The pulse names of tresillo and the three cross-beats of the hemiola are identical: one, one-ah, two-and.

: <score lang="lilypond">
{
       \relative c' <<
        \new Staff <<
           \new voice {
              \clef percussion
              \time 2/4
              \set Score.tempoHideNote = ##t \tempo 4 = 100       
              \stemDown \repeat volta 2 { g4 g }
       }
          \new voice {
              \set Score.tempoHideNote = ##t \tempo 4 = 100      
              \time 2/4
              \stemUp \repeat volta 2 { f'8.[ f16]^~ f8[ f8] } \bar ":|."
       } >>
       \new Staff <<
          \new voice {
              \clef percussion
              \time 2/4
              \set Staff.timeSignatureFraction = 6/8
              \scaleDurations 2/3 {
                 \set Score.tempoHideNote = ##t \tempo 8 = 100       
                 \stemDown \repeat volta 2 { g,4. g }
              }
       }
          \new voice \relative c' {
              \time 2/4
              \set Staff.timeSignatureFraction = 6/8
              \scaleDurations 2/3 {
                 \set Score.tempoHideNote = ##t \tempo 4 = 100      
                 \stemUp \repeat volta 2 { f4 f8^~ f f4 } \bar ":|."
              }
       } >>
  >> }
</score>

The composite pattern of tresillo and the main beats is commonly known as the ''[[habanera (music)|habanera]]'',<ref>Roberts, John Storm (1979: 6). ''The Latin tinge: the impact of Latin American music on the United States''. Oxford.</ref> ''congo'',<ref>Manuel, Peter (2009: 69). ''Creolizing Contradance in the Caribbean''. Philadelphia: Temple University Press.</ref> ''tango-congo'',<ref>Acosta, Leonardo (2003: 5). ''Cubano Be Cubano Bop; One Hundred Years of Jazz in Cuba''. Washington D.C.: Smithsonian Books.</ref> or ''tango''.<ref>Mauleón (1999: 4) ''Salsa Guidebook for Piano and Ensemble''. Petaluma, California: Sher Music. {{ISBN|0-9614701-9-4}}.</ref> The habanera rhythm is the duple-pulse correlative of the vertical [[hemiola]] (above). The three cross-beats of the hemiola are generated by grouping triple pulses in twos: 6 pulses ÷ 2 = 3 cross-beats. Tresillo is generated by grouping duple pulses in threes: 8 pulses ÷ 3 = 2 cross-beats (consisting of three pulses each), with a remainder of a partial cross-beat (spanning two pulses). In other words, 8 ÷ 3 = 2, r2. Tresillo is a cross-rhythmic fragment. It contains the first three cross-beats of 4:3. ''(Rumba,'' p. xxx)<ref name="Peñalosa 2010" />

: [[File:Tresillo Rhythm.ogv|right|200px|thumb|[[Tresillo (rhythm)|Tresillo]] over two Video]]<score lang="lilypond">
\layout {
  \context {
    \Score
    \remove "Timing_translator"
    \remove "Default_bar_line_engraver"
  }
  \context {
    \Staff
    \consists "Timing_translator"
    \consists "Default_bar_line_engraver"
  }
}

{
       \relative c' <<
        \new Staff <<
           \new voice {
              \clef percussion
              \time 4/4
              \set Score.tempoHideNote = ##t \tempo 4 = 100       
              \stemDown \repeat volta 2 { g4 g g }
       }
          \new voice {
              \set Score.tempoHideNote = ##t \tempo 4 = 100      
              \time 4/4
              \stemUp \repeat volta 2 { f'8.^\markup { "four against three" } f16^~ f8 f^~ f16 f8. } \bar ":|."
       } >>
       \new Staff <<
          \new voice {
              \clef percussion
              \time 3/4
              \set Score.tempoHideNote = ##t \tempo 8 = 100       
              \stemDown \repeat volta 2 { g,4 g }
       }
          \new voice \relative c' {
              \time 3/4
              \set Score.tempoHideNote = ##t \tempo 4 = 100      
              \stemUp \repeat volta 2 { f8.^\markup { "tresillo" } f16^~ f8[ f] } \bar ":|."
       } >>
  >> }
</score>

== Cross-rhythm, not polymeter ==
Early ethnomusicological analysis often perceived African music as [[meter (music)|polymetric]]. Pioneers such as [[A.M. Jones]] and Anthony King identified the prevailing rhythmic emphasis as metrical accents (main beats), instead of the contrametrical accents (cross-beats) they in fact are. Some of their music examples are polymetric, with multiple and conflicting main beat cycles, each requiring its own separate time signature. King shows two [[Yoruba music|Yoruba]] dundun pressure drum ("[[talking drum]]") phrases in relation to the five-stroke [[bell pattern|standard pattern]], or "[[clave (rhythm)|clave]]," played on the kagano dundun (top line).<ref>King, Anthony (1961). ''Yoruba Sacred Music from Ekiti'' p. 15. Ibadan: University Press.</ref> The standard pattern is written in a polymetric {{Time signature|7|8}} + {{Time signature|5|8}} time signature. One dundun phrase is based on a grouping of three pulses written in {{Time signature|3|8}}, and the other, a grouping of four pulses written in {{Time signature|4|8}}. Complicating the transcription further, one polymetric measure is offset from the other two.

[[File:King Polymeter.jpg|thumb|center|400px|Dundun drum ensemble represented as polymeter.]]

{{cquote|African music is often characterized as polymetric, because, in contrast to most Western music, African music cannot be notated without assigning different meters to the different instruments of an ensemble|25px|25px|Chernoff (1979: 45).<ref>Chernoff, John Miller (1979). ''African Rhythms and Sensibilities'' p. 45. Chicago: University Press.</ref>}}

More recent writings represent African music as cross-rhythmic, within a single meter.

{{cquote|Of the many reasons why the notion of polymeter must be rejected, I will mention three. First, if polymeter were a genuine feature of African music, we would expect to find some indication of its pertinence in the discourses and pedagogical schemes of African musicians, carriers of the tradition. As far as I know, no such data is available...Second, because practically all the ensemble music in which polymeter is said to be operative in dance music, and given the grounding demanded by choreography, it is more likely that these musics unfold within polyrhythmic matrices in single meters rather than in ... "mixed" meters ... Third, decisions about how to represent drum ensemble music founder on the assumption, made most dramatically by Jones, that accents are metrical rather than phenomenal...phenomenal accents play a more important role in African music than metrical accents. Because meter and grouping are distinct, postulating a single meter in accordance with the dance allows phenomenal or contrametric accents to emerge against a steady background. Polymeter fails to convey the true accentual structure of African music insofar as it creates the essential tension between a firm and stable background and a fluid foreground|25px|25px|Agawu (2003: 84, 85).<ref>Agawu, Kofi (2003). ''Representing African Music: Postcolonial Notes, Queries, Positions''. New York: Routledge.</ref>}}

{{cquote|[The] term ‘polymetric’ is only applicable to a very special kind of phenomenon. If we take "metre" in its primary sense of metrum (the metre being the temporal reference unit), ‘polymetric’ would describe the simultaneous unfolding of several parts in a single work at different tempos so as not to be reducible to a single metrum. This happens in some modern music, such as some of [[Charles Ives]]' works, [[Elliott Carter]]’s Symphony, [[Bernd Alois Zimmermann|B.A. Zimmermann]]’s opera "Die Soldaten," and [[Pierre Boulez]]’s "Rituel." Being polymetric in the strict sense, these works can only be performed with several simultaneous conductors|25px|25px|Arom (1991: 205).<ref>Arom, Sinmha (1991). ''African Polyphony and Polyrhythm: Musical Structure and Methodology'' p. 205. Cambridge University Press.</ref>}}

When written within a single meter, we see that the dundun in the second line sounds the main beats, and the subdivision immediately preceding it. The first [[cell (music)|cell]] (half [[bar (music)|measure]]) of the top line is a [[hemiola]]. The two dunduns shown in the second and third lines sound an embellishment of the three-over-four (3:4) cross-rhythm—expressed as three pairs of strokes against four pairs of strokes. ''(Clave Matrix'' p.&nbsp;216)<ref name="Peñalosa 2009" />
[[File:King correct cross-rhythm.jpg|thumb|center|400px|Dundun drum ensemble represented as cross-rhythm within a single meter.]]

== Adaptive instruments ==
Sub-Saharan instruments are constructed in a variety of ways to generate cross-rhythmic melodies. Some instruments organize the pitches in a uniquely divided alternate array – not in the straight linear [[Bass (sound)|bass]] to [[Treble (sound)|treble]] structure that is so common to many western instruments such as the [[piano]], [[harp]], and [[marimba]].

[[Lamellophone]]s including [[mbira]], mbila, mbira huru, mbira njari, mbira nyunga, marimba, karimba, [[kalimba]], likembe, and okeme.  These instruments are found in several forms indigenous to different regions of Africa and most often have equal tonal ranges for right and left hands. The [[kalimba]] is a modern version of these instruments originated by the pioneer ethnomusicologist [[Hugh Tracey]] in the early 20th century which has over the years gained world-wide popularity.

[[File:TrebleKalimba.jpg|thumb|left|180px|Hugh Tracey Treble [[Kalimba]]]]
[[File:Gravikord.JPG|150px|thumb|right|Signature Series [[Gravikord]]]]

[[Chordophone]]s, such as the West African [[kora (instrument)|kora]], and Doussn'gouni, part of the [[harp-lute]] family of instruments, also have this African separated double tonal array structure. Another instrument, the [[Marovany]] from Madagascar is a double sided box zither which also employs this divided tonal structure. The [[Gravikord]] is a new American instrument closely related to both the African kora and the kalimba. It was created to exploit this adaptive principle in a modern electro-acoustic instrument.<ref name="Gravikord-web" />

On these instruments one hand of the musician is not primarily in the bass nor the other primarily in the treble, but both hands can play freely across the entire tonal range of the instrument. Also the fingers of each hand can play separate independent rhythmic patterns and these can easily cross over each other from treble to bass and back, either smoothly or with varying amounts of [[syncopation]]. This can all be done within the same tight tonal range, without the left and right hand fingers ever physically encountering each other. These simple rhythms will interact musically to produce complex cross rhythms including repeating on beat/[[Off-beat (music)|off beat]] pattern shifts that would be very difficult to create by any other means. This characteristically African structure allows often simple playing techniques to combine with each other and produce cross-rhythmic music of great beauty and complexity.

== Jazz ==
''The New Harvard Dictionary of Music'' calls [[swing (jazz performance style)|swing]] "an intangible rhythmic momentum in jazz," adding that "swing defies analysis; claims to its presence may inspire arguments." The only specific description offered is the statement that "triplet subdivisions contrast with duple subdivisions."<ref>''The New Harvard Dictionary of Music'' (1986: 818). Cambridge, MA: Harvard University Press.</ref> The argument could be made that by nature of its simultaneous triple and duple subdivisions, swing is fundamentally a form of polyrhythm. However, the use of true systematic cross-rhythm in [[jazz]] did not occur until the second half of the twentieth century.

=== 3:2 (or 6:4) ===

In 1959 [[Mongo Santamaria]] recorded "[[Afro Blue]]," the first jazz standard built upon a typical African 3:2 cross-rhythm.<ref name="Mongo Santamaria 1959" group=lower-alpha /> The song begins with the bass repeatedly playing 3 cross-beats per each measure of {{Time signature|6|8}} (3:2), or 6 cross-beats per {{Time signature|12|8}} measure (6:4). The following example shows the original [[ostinato]] "Afro Blue" bass line. The slashed noteheads are not bass notes, but are shown to indicate the main [[beat music|beats]], where you would normally tap your foot to "keep time."

: <score>
    \new Staff <<
       \new voice \relative c {
           \set Staff.midiInstrument = #"acoustic bass"
           \set Score.tempoHideNote = ##t \tempo 4 = 105
           \time 12/8
           \clef bass        
           \stemUp \repeat volta 2 { d4 a'8~ a d4 d,4 a'8~ a d4 }
       }
       \new voice \relative c {
           \override NoteHead.style = #'cross
           \stemDown \repeat volta 2 { g4. g g g }
       }
   >>
</score>

=== 3:4 ===
On the original "Afro Blue," drummer [[Willie Bobo]] played an [[abakuá]] [[bell pattern]] on a snare drum, using brushes. This cross-rhythmic figure divides the twelve-pulse cycle into three sets of four pulses. Since the main beats (four sets of three pulses) are present whether sounded or not, this bell pattern can be considered an embellishment of the three-against-four (3:4) cross-rhythm. Bobo used this same pattern and instrumentation on the [[Herbie Hancock]] jazz-descarga "Succotash."<ref name="Hancock-Succotash" group=lower-alpha />

=== 2:3 ===

In 1963 [[John Coltrane]] recorded "[[Afro Blue]]" with the jazz drummer [[Elvin Jones]].<ref name="Coltrane-Jones Afro Blue" group=lower-alpha /> Jones inverted the metric hierarchy of Santamaria's composition, performing it instead as duple cross-beats over a {{Time signature|3|4}} "jazz waltz" (2:3). This 2:3 in a swung {{Time signature|3|4}} is perhaps the most common example of overt cross-rhythm in jazz.<ref name="Guilfoyle Youtube" group=lower-alpha />

[[File:3-4 cross-rhythm-2.png|thumb|center|160px|Two-over-three (2:3).]]

=== Duple-pulse correlative of 3:2 ===

The [[Wayne Shorter]] composition "[[Footprints (composition)|Footprints]]" may have been the first overt expression of the 6:4 cross-rhythm (two cycles of 3:2) used by a straight ahead jazz group.<ref name="Miles-Footprints 1967" group=lower-alpha /> On the version recorded on ''[[Miles Smiles]]'' by [[Miles Davis]], the bass switches to {{Time signature|4|4}} at 2:20. The {{Time signature|4|4}} figure is known as [[tresillo (rhythm)|tresillo]] in Latin music and is the duple-pulse correlative of the cross-beats in triple-pulse. Throughout the piece, the four main beats are maintained. In the example below, the main beats are indicated by slashed noteheads. They are shown here for reference and do not indicate bass notes.

: <score lang="lilypond">
{
       \relative c, <<
        \new Staff <<
           \new voice {
              \clef bass \time 12/8 \key c \minor
              \set Score.tempoHideNote = ##t \tempo 4 = 100       
              \stemDown \override NoteHead.style = #'cross \repeat volta 2 { es4. es es es }
       }
          \new voice {
              \set Score.tempoHideNote = ##t \tempo 4 = 100      
              \time 12/8
              \stemUp \repeat volta 2 { c'4 g'8~ g c4 es4.~ es4 g,8 } \bar ":|."
       } >>
       \new Staff <<
          \new voice {
              \clef bass \time 12/8 \key c \minor
              \set Staff.timeSignatureFraction = 4/4
              \scaleDurations 3/2 {
                  \set Score.tempoHideNote = ##t \tempo 8 = 100       
                  \stemDown \override NoteHead.style = #'cross \repeat volta 2 { es,4 es es es }
              }
       }
          \new voice \relative c' {
              \time 12/8
              \set Staff.timeSignatureFraction = 4/4
              \scaleDurations 3/2 {
                  \set Score.tempoHideNote = ##t \tempo 4 = 100      
                  \stemUp \repeat volta 2 { c,8. g'16~ g8 c es4~ es8. g,16 } \bar ":|."
              }
       } >>
  >> }
</score>

In recent decades, jazz has incorporated many different types of complex cross-rhythms, as well as other types of polyrhythms.

==See also==
*[[Hemiola]]
*[[Syncopation]]

== References ==
'''Audio-visual samples and references to recordings'''
{{reflist|group=lower-alpha|30em|refs=

<ref name="Guilfoyle Youtube" group=lower-alpha>[https://www.youtube.com/watch?v=OEAyWsTLrYY "Jazz Drumming in {{Time signature|3|4}}"] (part 2), by Conor Guilfoyle, [[YouTube]]
:Guilfoyle demonstrates 2:3 cross-rhythm in {{Time signature|3|4}} swing.</ref>

<ref name="Coltrane-Jones Afro Blue" group=lower-alpha>[https://www.youtube.com/watch?v=olOYynQ-_Hw "Afro Blue"], [[YouTube]], [[John Coltrane|John Coltrane Quartet]]
: Album: ''[[Afro Blue Impressions]]''
: [[Pablo Records|Pablo-Live]] (G)PL2620-101 (1977)
: {{oclc|173207839}}
: Live, Auditorium Maximum, [[Free University of Berlin]], November 2, 1963
: [[John Coltrane]] (soprano & tenor sax), [[McCoy Tyner]] (piano), [[Jimmy Garrison]] (bass), [[Elvin Jones]] (drums) {{webarchive |url=https://web.archive.org/web/20070217004822/https://www.youtube.com/watch?v=olOYynQ-_Hw |date=February 17, 2007 }}</ref>

<ref name="Miles-Footprints 1967" group=lower-alpha>"Footprints," [[Miles Davis|Miles Davis Quintet]]
: Album: ''[[Miles Smiles]]'', [[Columbia Records|Columbia]] CS 9401; CD (1967)
: {{oclc|872563570|41265755|872667474}}
: Recorded 1966 October 24–25, 1966, [[CBS 30th Street Studio|Columbia 30th Street Studio]], New York City
: [[Miles Davis]] (trumpet), [[Wayne Shorter]] (tenor sax), [[Herbie Hancock]] (piano), [[Ron Carter]] (bass), [[Tony Williams (drummer)|Tony Williams]] (drums)</ref>

<ref name="Hancock-Succotash" group=lower-alpha>"Succotash," [[Herbie Hancock]]
: Album: ''[[Inventions and Dimensions]]''  [[Blue Note Records|Blue Note]] CD 84147-2 (1963)
: {{oclc|20227090|874388051}}
: Recorded at the [[Van Gelder Studio]], [[Englewood Cliffs, New Jersey]], August 30, 1963
: [[Herbie Hancock]] (piano), [[Paul Chambers]] (bass), [[Willie Bobo]] (drums, [[timbales]]), Osvaldo "Chihuahua" Martinez (conga, bongo)</ref>

<ref name="Aña_Jiménez-Rhythms 1994" group=lower-alpha>"Changó," Ilu Aña and Regino Jiménez
: Album: ''Sacred Rhythms'', Bembe CD 2027-2 (1994)
: {{oclc|460783709|858557089|33976057}}, {{oclc|30784345}}</ref>

<ref name="Muñequitos=Beodos 1956 v. 1" group=lower-alpha>"Los Beodos" ("The Drunk") (side A, 2nd track, at 2:11), [[Los Muñequitos de Matanzas]] (originally known as Grupo Guaguancó Matancero)
: Album: ''Guaguancó'', Vol. 1, Grupo Guaguancó Matancero, Puchito MLP 565 (1956)
: {{oclc|14715894}}; {{oclc|431807544}}</ref>

<ref name="Muñequitos=Beodos 1956 v. 2" group=lower-alpha>"Cantar Maravilloso" ("Wonderful Song") (at 2:24), [[Los Muñequitos de Matanzas]] (originally known as Grupo Guaguancó Matancero)
: Album: ''Guaguancó'' Vol. 2, Grupo Guaguancó Matancero, Antilla MLP 595 (1958)
: Original release: Puchito SP 103 ([[LP record|LP]])</ref>

<ref name="Mongo Santamaria 1959" group=lower-alpha>"[[Afro Blue]]," [[Mongo Santamaria]]
: Album: ''Afro Roots'', [[Fantasy Records|Fantasy]] 8032 (1959)
: {{oclc|29751149|3209055|20288150}}</ref>

}}

'''Inline citations'''
{{Reflist|30em|refs=
<ref name="Jones 1959">[[Arthur Morris Jones|Jones, A.M.]] (1959). ''Studies in African Music'' (vol. 1 of 2). London: [[Oxford University Press]]. 1978 edition, pg. 102; {{ISBN|0-19-713512-9}}; {{oclc|611586}}.</ref>

<ref name="Ladzekpo 1995">Ladzekpo, C.K. (1995).<div style="margin-left:2em">''Foundation Course in African Dance-Drumming; {{oclc|44366373}}''</div>
:a: "The Myth of Cross-Rhythm"
:b: "Main Beat Schemes"
:c: "Six Against Four Cross-Rhythm"
:d: "Three Against Four Cross-Rhythm"</ref>

<ref name="Peñalosa 2009">Peñalosa, David (2009). ''The Clave Matrix, Afro-Cuban Rhythm: Its Principles and African Origins.'' [[Redway, California]]: Bembe Inc., pps. 21, 22, 35, 216; {{ISBN|1-886502-80-3}}; {{oclc|466422227}}</ref>

<ref name="Gravikord-web">[http://www.gravikord.com/instrument.html#gravikord "The 'Gravikord,'"] ({{URL|http://www.gravikord.com/instrument.html#gravikord}})</ref>

<ref name="Peñalosa 2010">Peñalosa, David (2010). ''Rumba Quinto'', [[Redway, California]]: Bembe Books; {{ISBN|1-4537-1313-1}}; {{oclc|806336780}}</ref>

<ref name="Coburg 2004">Coburg, Adrian (2004). "{{Time signature|6|8}} toque de la rama efí," ''Percusion Afro-Cubana'' (vol. 1 of 2: ''Muisca Folklorico)'' Bern: Coburg Percussion Publishing, p. 1; {{oclc|823726876}}</ref>

<ref name="Kubik 1999">[[Gerhard Kubik|Kubik, Gerhard]] (1999). Africa and the Blues. [[Jackson, Mississippi]]: [[University Press of Mississippi]]; {{oclc|44959610}}</ref>

<ref name="Locke 1982">Locke, David Laurence (1982). "Principles of Off-Beat Timing and Cross-Rhythm in Southern Ewe Dance Drumming," ''Ethnomusicology'', [[Society for Ethnomusicology]], November 11; {{issn|0014-1836}}</ref>

<ref name="Locke 2011">Locke, David Laurence (2011). [http://www.aawmjournal.com/articles/2011a/Locke_AAWM_Vol_1_1.pdf "The Metric Matrix: Simultaneous Multidimensionality in African Music,"] ''Analytical Approaches To World Music'', Vol. 1, No. 1 (p. 56; out of pps. 48–72); {{ISSN|2158-5296}}</ref>

}}

{{Rhythm and meter}}

{{DEFAULTSORT:CrossBeat}}
[[Category:African rhythm]]
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[[Category:Musical terminology]]
[[Category:Jazz terminology]]