Harmonic analysis of the first A section of Boplicity
Boplicity’s A sections are particularly interesting as almost every melody note is harmonised with 4 other pitch classes to create a 5-part chord. At a moderate swinging tempo the melody and harmony advance rather quickly creating a dense and rich sound.
Some clarification of terms is necessary first:
Target chord – The chord that was aimed toward in the harmonisation. The target chord usually occurs at a melodically or rhythmically important point in the bar and can help explain what harmony precedes and proceeds that moment.
Functional chord – A chord that has a dominant function (V), it leads to a target or other chord. It is often a secondary dominant.
Diatonic chord – A chord that is within the key but does not function, secondary dominants that don’t lead to their respective I’s are included in this category. It is often used to “plane” in scalar passages.
Voice Leading/Other chord – A chord that is hard to define and usually arrived at via voice leading or to create a particular sound.
Boplicity – Bars 1&2
In the examples I have named the chord above each note and the chord above the bass part is from the original lead sheet.
The highlighted chords are target chords. The Gm9b5 I consider to be a target chord as it is melodically important and it is the II which sets up the “silent” V (notice the bass part) before the next Fmaj9.
The chords circled in red are functional chords. All the G minor chords function as II chords. The E7b9 and Am7/D are interesting and have a double function. The E7 as a V to the Amin and the Am7/D or D9sus as a V to the Gm9b5.
The chord circled in green is in the voice leading/other category. It could be argued that it functions like a dominant and is just a altered V chord (C7susb9b5), but its an interesting sound and worth a closer look either way.
I include the Gbm6/9 as a target chord as it is such a sweet sound and it must have been planned for on such an important note of the phrase.
There are diatonic chords used in these bars. The Gmi9 in bar 3 doesn’t function as a II and the Eb chords in bar 4 are just chord tones from the Cmi9, F7 key area. The chord in green is a real cracker and I consider it to be a chord arrived at via voice leading.
Bars 5 and 6 start with another voice leading/other chord. The Gmi9 and A7b9’s are diatonic and are just to “plane” to the next chord.
The Gmi7/C in bar 6 could be seen as a target or diatonic. It is sort of both, but with the next two bars in mind I think it is diatonic.
I have the Csus7b9 and Fsus7b9 as target chords as they represent a very intentional moment where the bass and melody become in unison two octaves apart. The Gmi7 at the start of the bar functions as a II chord.
The Ebsus7b9 chord is an instance of true “planing” and hence isn’t diatonic or functional in this case. So it must live in the other category.