From Jazz Guitar Harmony
by Jody Fisher
To reharmonize a tune is to change its fundamental harmony. This is not the same thing as chord substitution, where the nature of the harmony
remains the same—no matter how disguised the chords may become. For example, extending and altering dominant chords changes the flavor
of the harmony, but there is always a way to justify these devices as being just enhancements. Reharmonization throws some or all of the original changes out the window. This, however, is not simply a matter of “just playing whatever you want.” To create an artful and creative reharmonization, one must follow a general set of guidelines based on which system of reharmonization you choose.
Following is one method of reharmonization. This is a huge topic and many more reharmonization techniques exist, but the material shown
here should get you started.
Symmetrical Bass Line Approach
With this technique, you start with just the melody and then add the accompaniment of an interesting bass line. Below is a melody (let’s
assume its from a standard tune you already know) with an added bass line. The key to this technique is that the bass line should be symmetrical—the pattern of intervals between the notes is unchanging. (Feel free to jump octaves when necessary.) In this example, the bass line moves
in minor 3rds (or augmented 2nds, which is the same distance) throughout the song.
Jazz’n Java With A Symmetrical Bass Line