Editing Polyrhythm (section)

=== Adaptive instruments ===
Sub-Saharan instruments are constructed in a variety of ways to generate polyrhythmic 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]], or [[marimba]].
[[File:TrebleKalimba.jpg|thumb|left|180px|Hugh Tracey Treble [[Kalimba]]]]

[[Lamellophone]]s including [[mbira]], mbila, mbira huru, mbira njari, mbira nyunga, marimba, karimba, [[kalimba]], likembe, and okeme. This family of 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 worldwide popularity.

[[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.<ref name="Alves2013">{{cite book|author=William Alves|title=Music of the Peoples of the World|url=https://books.google.com/books?id=6fkJAAAAQBAJ&pg=PA63|date=12 April 2013|publisher=Cengage Learning|isbn=978-1-133-71230-5|page=63}}</ref>{{clarify|date=May 2012}}Another instrument, the [[Marovany]] from Madagascar is a double sided box zither which also employs this divided tonal structure. [[Trough zither]]s also have the ability to play polyrhythms.

The [[Gravikord]] is a new American instrument closely related to both the African kora and the kalimba was created in the latter 20th century to also exploit this adaptive principle in a modern electro-acoustic instrument.<ref>The Gravikord web site : http://www.gravikord.com/instrument.html#gravikord</ref>

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 to produce polyrhythmic music.