Harmony: Modern Serious Music, Jazz

As music evolved, particularly in the 19Th Century, through Wagner and beyond to Schoenberg and the nationalist composers of the 20Th century, there was a loosening and even abandonment of rules of harmony. First, harmony where the triads function to lead to one another in well defined and strict rules is called "Functional Harmony", and most of the music you will ever hear adheres to these rules even a century after Schoenberg. But what Wagner underscored in the Overture to Tristan and Isolde was that harmony could operate outside the rules of functional harmony. As the century progressed and into the last century even this competitive freedom was overstepped and we got atonal or serial music that purported to have no harmony. At the same time, national music movements headed by composers like Stravinsky, Debussy, and Bartok, to name a few added new modes to the serious traditions based on modes used in their ethnic heritage.

In the U.S. Jazz was the benefactor of this infusion of influences and so Jazz harmony is non-functional or if functional it is heavily altered by chromaticism. Even the simple act of substituting the dominate seventh chords for each functional equivalent of I, IV, and V in standard blues is such an alteration, but the Jazz musicians drew on much more than that reading Debussy, Stravinsky, etc. for ideas on altered chords.

One thing to be said about efforts to free music of harmony is that even in so-called twelve tone music a tonal center appears to somehow emerge, and beyond that, avoiding the rules of formal harmony, a new harmony emerges that reflects modal ideas. It is as though music history came full circle and rediscovered something like the old church modes with the Greek names that appeared at the beginning of the development of the western serious music tradition.