When discussing aspects of Shona music we pointed out that an mbira song's 48 beats can be organized as four phrases of 12 beats, and each phrase can be divided into three groups of four, or four groups of three. In this way mbira music is especially noteworthy, as it merges 4/4 and 3/4 time. Mbira music takes advantage of this by creating polyrhythms, in which the duple and triple meters can be heard at the same time. Often, the music is not clearly one time signature or the other, but rather a beautifully ambiguous combination of the two.
Much mbira music is predominantly heard and felt in a triplet-subdivided I2/8, although there are pieces in duple-subdivided 3/4. The creative potential of 3:2 relationships characterize many mbira pieces; often one hand is "in three or six” while the other is 'in two or four.”
Polyrhythms are also created by the distinct lines perceived in the different registers of the instrument. Of the various (high and low) lines that the ear naturally picks out, one line will sound like it belongs to one meter, while at the same time another line sounds like it belong to a different, contrasting meter. Along with the contrapuntal and harmonic effects, this polyrhythmic effect contributes to a subtle complexity that many listeners, even outside of the Shona tradition, find quite compelling.
Many mbira parts have patterns that are clearly duple. Often the kushaura player alternates between left and hand. This Nhemamusasa kushaura, for example, moves from L (top left) to R (right) to B (bottom left) to R to L to R . . . Such a structure is hard to not hear as rhythmic patterns of twos or fours.
But, in fact, the song is strongly heard and sung in threes,
as the hosho beat helps emphasize.
Because the fingering is so strongly duple it can be a real challenge for the beginning mbira player to hear and play such a part with the appropriate triplet rhythm.
This conundrum is often one of a new mbira player's first experiences. New students of mbira are often taught the kushaura to Kariga Mombe first. This kushaura is a string of pairs of notes:
But the hosho rhythm is, as is usually the case, firmly in threes.
The 3:2 relationships in mbira music are central to the feel of the music but can be a challenge to Western or Eastern ears not accustomed to such polyrhythm. As David Locke points out:
Creative, participatory listening is an essential aspect of this music-
culture. Performer and audience must hear coherent melodies in the mbira's
numerous tones. Many pieces exploit the creative potential of 3:2 relationships; often one hand is 'ln three or six” while the other is 'in two or four.” Hand-clapping phrases provide a good way to join in the performance and experience this polymetric feeling.David Locke — Worlds of Music: An Introduction to the Music of the World's Peoples
The hosho plays an essential role in mbira music, driving the beat.
The player will show in this paragraph
As well, in many mbira songs (such as Nhemamusasa below) the kutsinhira parts emphasize the triplet rhythm by placing bass notes emphatically on the beat.
Paul Berlner has pointed out that polyrhythms that jazz musicians employ at times to animate their music are actually built into the forms of many mbira compositions.
That discipline is essential for mbira players. Polyrhythmic architecture provides the foundation for their world of imagination. It is this world that that they operate within, exploring all the possibilities for invention it enables. Ultimately, they use polyrhythmic resources to explore ideas that are melodic and harmonic in character, and to create rhythmic ideas that have increasingly-abstract relationships to the beat.Paul Berliner — The Soul of Mbira
In The Soul of Mbira Paul presents many examples of the myriad polyrhythmic ideas that come out of the interaction of kushaura parts, kutsinhira parts and hosho. (Some of this is available on Google Books .)