How does this lick work harmonically?

Question

Here is the lick (3:38 - 3:39).

He is playing it over a F minor chord. The key of the song is Ab. It looks like he just playing extentions of the F minor chord. What is a better way to explain this?

Answer 1

He's playing a pentatonic scale pattern, harmonized in fourths, which is a common device in jazz. Open fourths give an ambiguous sense of harmony even though, in this case, he never actually leaves the home key.

Ab Major = Ab Bb C Db Eb F G and an F minor chord, F Ab C, is the vi chord, consisting entirely of notes within the Ab Major scale.

The primary (upper) notes of the solo are Eb F Ab Bb C Eb F Ab, which is an F minor pentatonic (also Ab major pentatonic) scale, starting on Eb. By using the pentatonic scale, both E natural (the leading tone in F minor) and G natural (the leading tone in Ab major) are avoided, giving a sense of tonal ambiguity even though all of the pitches are within the key/scale. This is enhanced by starting on Eb rather than F or Ab.

Harmonizing the scale at the fourth below gives Bb C Eb F *Ab* Bb C Eb. Note that the pattern breaks at the Ab. This keeps the harmony within the pentatonic scale and avoids the G natural (Ab leading tone). This use of fourths also reinforces the tonal ambiguity while staying within the key.

This is a basic example of "quartal harmony".

The pianist McCoy Tyner, among others, is particularly well known for using quartal chord voicings. A clear example can be heard in the opening vamp on "My Favorite Things" from the album Coltrane: Live at the Half Note.

Answer 2

He plays the following notes (disregard the rhythm values):

X: 1  
K: C
L: 1/4   
[_B,_E] [CF] [_E_A] [F_B] [_Ac] | [_B_e] [cf] [_e_a] [f_b] |

It is an (almost) constant interval moving up over the notes of F minor pentatonic (F Ab Bb C Eb). However, in this context I wouldn't call it "extension", but rather a passage, transition.