3.3 Mbira  (Page 4/6)

Form

The form of a typical mbira song is cyclical ; that is, it is based on a continuous repetition of the tune. The basic tune of a piece usually has four phrases of equal length. This type of form is very common for lamellophone music throughout Africa, although the traditions for some instruments feature two-phrase rather than four-phrase melodies.

The music at a bira may need to continue for many hours; it is not uncommon for the ceremony to last all night, with only short breaks in the music. It is not unusual to play a single tune for a very long time, repeating the four-phrase melody many, many times. The music is kept interesting by a constant subtle variation on the basic tune. Most traditional pieces have more than one standard version of the melody. The player can switch between the versions, and can also improvise by changing some of the notes.

Most interestingly, the rhythm and texture of the basic melody are so complex that the player can provide "variations" on the tune simply by shifting the accents or emphasis on certain notes, or by singing along with certain notes, in order to bring out different aspects or relationships within the melody. An accomplished mbira player is so skilled at creating and elucidating interesting variations that he can keep a crowd happy while playing the same tune for hours.

Timbre and texture

The mbira dzavadzimu is constructed in a way that makes it very easy to jump between high-, low-, and medium-pitched tones. The typical mbira melody takes advantage of this, jumping quickly between the different octaves of the three manuals . Rather than hearing this as a single multi-octave melody, the listener naturally groups the high notes together into a high "melody" and the low notes into a contrasting low "melody". The notes in the middle range often seem to belong to their own, third, independent melody. This gives the music a rich contrapuntal texture , even though normally only one note is played at a time. (Bach's sonatas for unaccompanied violin or cello famously use this same "auditory illusion", producing counterpoint from a single line that bounces back and forth between high and low "melodies".)

It is this auditory illusion that allows the most subtle, and interesting, variations on the tune. It can be unclear which melody (high, medium, or low) a particular note belongs to; one note might be either a low note in the high melody, for example, or a high note in the middle melody. Thus, by making subtle shifts in accent and emphasis, or by shifting a pitch in a variation, the player can make a note "jump" from one melody to another, or can make melodies seem to appear and disappear while still playing the same sequence of notes. By bringing out a variety of inner lines in this way, the skilled player can make the same sequence of notes sound like a completely different piece of music.

In addition to creating this interlocking conterpoint, the intervals between successive pitches in the pattern tend to be octaves , fifths , and thirds (the same intervals found in Western major and minor chords ). This creates a strong impression of harmony (in the same way as a piano playing arpeggios ), often including an impression of harmonic motion or progression within each phrase, and of changes in harmony as the variations are played.