Extended Harmony: The Role of Sevenths
If you want to become an advanced bassist, studying jazz theory is a must. Believe it or not, jazz theory can spice up your rock and pop playing too. For example, a close inspection of some of the Beatles' most interesting tunes reveals the use of chord progressions and tricks of the trade often associated with jazz and classical music. In many ways, that's why their songs are so compelling. Furthermore, if you study harmonically sophisticated music (such as jazz) you will simply be more informed and knowledgeable as a musician. The more informed you are, the easier it will be to play any style of music.
One of the things that jazz is known for is its use of extended harmony. More than just about any other form of music, jazz stretches harmonic complexity to the max. Extended harmonies revolve around adding notes, in stacked thirds, beyond the simple triad. These extensions might be sevenths, ninths, elevenths, and/or thirteenths. They add color to the music while simultaneously assigning a deeper function to a chord. So, extensions change or augment the emotive content of a chord while they also help to delineate the specific harmonic role of that chord.
When utilizing extended harmonies, there are both aesthetic and functional considerations. The aesthetic aspect relates to individual chord colors while the functional aspect refers to how a chord is used contextually, that is, the relationship between chords. In short, the chord progression reveals the quality and function of each chord as well as enhancing a basic aesthetic component.
At first it may be difficult to differentiate between each kind of chord extension, but through careful listening and dedicated application you can learn to hear their differences. In time, you will also learn how these various extensions may be used. Start with sevenths.
Sevenths were introduced in Chapter 7, and it might be helpful to review that chapter before tackling this section. There are two completely different kinds of sevenths: major sevenths and minor sevenths. Major sevenths are spelled out as maj7, D
Aesthetically speaking, a maj7 chord has a sweet sound and is patently pretty. Maj7 assigns a function generally associated with I or IV chords in a major key, though they may also accompany minor chords. In this case, they exude the classic sound of film noir. Think of the eerie chords you often hear in black-and-white detective movies!
Dominant seventh chords — written like D7, F#7, and B7 — are commonly attached to both major and minor triads. When used as an extension of a major chord, they are generally bluesy sounding. When used in most chord progressions where blues is not an emphasis, the functional aspect of the chord comes to the fore and the dominant seventh, on a major triad, expresses itself as a V7 chord. Since V chords are powerfully drawn to a subsequent I chord, they often are followed by a progression to the I. On the other hand, when the dominant seventh is attached to a minor triad, the chord has a quintessentially jazzy and hip sound. Although in modern music this chord is often seen as an i chord in a minor key, it implies modal diatonicism (Dorian) and is most commonly associated with the functionality of the ii chord in a major key.
In order to internalize these sounds and understand these functions better, try the exercises in Figures 17-1 to
Seventh chord review
Listen carefully to each arpeggio. Pause between each to appreciate their distinct sound and composition.
Major triads with major sevenths over a Gmaj7
Notice the multiple symbols that may be used to represent a G major 7 chord.
Major triads with dominant sevenths over a G7
Minor triads with major sevenths over a Gm(maj7)
Minor triads with dominant sevenths over a Gm7
A ii-V-I progression using sevenths