Voicings
"A common way to harmonize tunes 'as you go along' in jazz piano (ie, freely and flexibly) is known as block chords: the hands move in parallel, providing a chord for each note of the melody. This often uses a technique derived from the way jazz arrangers write for four horns...or four trumpets: this is called four-way close."
There are a variety of voicings or methods:
- Generic block chord describes those that simply follow the above rule.
- Double melody (Commonly called the "Shearing voicing") with an additional fifth part that doubles the melody an octave lower.
- Drop 2 (technically not a block chord) with the second voice from the top transposed one octave lower.
If the melody note is part of the chord, the harmony notes are also taken from the chord.
This is a good technique if the melody note is diatonic (and not chromatic) and uses diminished chords for the notes that are not part of the chord. If the melody note is considered a passing tone, the harmony is created either by a diminished chord or a chromatically shifted chord. Before creating the harmonies, the chords could be converted to 6th chords, but this is not a rule.
Read more about this topic: Block Chord