Jazz is a remarkably dynamic musical art. At the beginning of the 20th century it began to bear its first fruits, only half a century later, just after the mid-50s, it had already covered a very wide range of styles, quite different from each other, although all of them were based on new musical parameters, in an unleashed musical creativity and the amazing technique of its protagonists. Let’s analyze some of its musical parameters, such as rhythm, melody, and harmony.
The uniqueness of rhythm in jazz derives from two main sources: that the musicians call “swing” and the concept of “democratization” of rhythmic values. Both characteristics derive basically from African musical backgrounds. The swing is something tricky to define. In the most classical sense, it means a constant rhythmic pulse. But in that sense, all music has a swing, including classical. However, jazz swing presents characteristics that are missing in classical music, even though these genres are still closely related.
Afro-American music didn’t have harmony in the specific sense of the term, that is, a functional diatonic harmony. But to say that the harmonic nature of jazz comes exclusively from Western influences is simplifying, although these are the predominant ones.
African music does not have the reciprocal relationship
between melody and harmony characteristic of European music, the
African-American assimilated the simplest harmonies of the Western tradition,
but within their original melodic conceptions.
Therefore, a melodic repertoire of native African origin was inserted within the harmonic framework of the western musical tradition. And while the concept of harmony is very different in European and Western African music, there were interesting intersections. If you like, hybrids that have enriched the sonority of jazz.
The melodic scale of jazz is a direct legacy of blues, created from identical chords formed by five notes. Considering that the evolution of the blues scale in the prehistory of jazz, in the earliest blues, like those of Bessie Smith, two particular forms of tetrachords were used rather separately (one or the other) and rarely together. In the most modern versions, as well as improvised instrumental jazz, both were used indistinctly since the decade of the ’20s.
It has also been perceived the importance of the 7th note lowered in the blues, in the early blues the seventh blue (AKA the blue note) had a certain tendency to be slightly lower in tuning and more stable than the third blue, that reconnects with the African melodic practices
The melodic-harmonic ambiguities of African origin are directly related to the “riffs” that appear in blues and that later were transferred to jazz: In a blues, a short phrase, of few notes, is repeated almost identically while the accompanying chords change in the 1st and 2nd repetitions.
This repetitive nature of the riff corresponds to the repetitive structure of African dance songs, especially those of work and fun. What was originally a secondary and intuitive resource, ended up being used as a material of first importance in the “riff melodies” of the Swing era.