The Complete Idiot''s Guide to Music Theory

Part 5:
Embellishing
204
Chord extensions can make a basic chord sound lush and exotic. There’s noth-
ing like a minor seventh or major ninth chord to create a really full, harmoni-
cally complex sound.
Seventh chords—especially dominant seventh chords—are common in all types
of music today. Sixths, ninths, and other extended chords are used frequently in
modern jazz music—and in movie and television soundtracks that go for a jazzy
feel. Pick up just about any jazz record from the 1950s on, and you’ll hear lots
of extended chords. There are even a lot of rock and pop musicians—Steely
Dan comes to mind—who embrace these jazz harmonies in their music.
So why not use this technique yourself?
Here’s an example of how extended chords can make a simple chord progres-
sion sound more harmonically complex. All you have to do is take the standard
I-vi-IV-V progression in the key of C (C-Am-F-G) and add diatonic sevenths
to each triad. That produces the following progression: CM7-Am7-FM7-G7—
two major sevenths, a minor seventh, and a dominant seventh. When you play
this progression—and invert some of the chords to create a few close voicings—
you get a completely different sound out of that old workhorse progression.
And it wasn’t hard to do at all!
Seventh chords have been part of the musical vocabulary from about the seven-
teenth century. There is a tendency to use the V7 and ii7 chords as much as or
more than the triads on those degrees of the scale—even for the simplest musical
genres, such as hymns and folk songs. In the blues, it is common to use seventh
chords on every scale degree—even the tonic.
Other extended chords (ninths, elevenths, and so forth) came into widespread use
in the nineteenth century, and are still used in many forms of music today. (Chopin is
often cited as one of the first composers to extensively use extended chords.) For
example, in many jazz compositions the ninth, eleventh, and thirteenth chords are
used more often than triads and seventh chords.
Note
The standard I-vi-IV-V progression (in C) embellished with seventh chords (and some close 
voicings).
You can get the same effect by adding ninths and elevenths to your chords
while staying within the song’s underlying key. The more notes you add to your
chords, the more complex your harmonies—and the fuller the sound.

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Chapter 16:
Chord Substitutions and Turnarounds
205
Altering the Bass
Here’s another neat way to make old chords sound new—and all you have to do
is change the note on the bottom of the chord.
Back in Chapter 9 we touched briefly on the concept of 
slash chords,
more prop-
erly called 
altered bass chords
. With an altered bass chord, the top of the chord
stays the same; but the bass, as the name implies, is altered.
Some folks call these chords slash chords because the altered bass note is indi-
cated after a diagonal slash mark, like this: G/D. You read the chord as “G over
D,” and you play it as a G chord with a D in the bass.
Examples of slash chords.
You can use altered bass chords to achieve several different effects, including
the following:
◆
By putting one of the three main notes (but not the root) in the bass, you
dictate a particular chord inversion.
◆
By treating the bass note as a separate entity, you can create moving bass
lines with increased melodic interest.
◆
By adding a nonchord note in the bass, you create a different chord with a
different harmonic structure.
Slash chords are used a lot in jazz, and also in more sophisticated popular
music. Listen to Carole King’s 
Tapestry
album and you’ll hear a lot of altered
bass (she’s a big fan of the minor seventh chord with the fourth in the bass); the
same thing with a lot of Beach Boys songs, especially those on the legendary 
Pet
Sounds
album.
Two Chords Are Better Than One
An altered bass chord uses a diagonal slash mark to separate the chord from the
bass note. When you see a chord with a horizontal line between two different
notes, like a fraction, you’re dealing with a much different beast.
This type of notation indicates that two chords are to be played simultaneously.
The chord on top of the fraction is placed on top of the pile; the chord on the 
bottom is played underneath. For example, when you see 
you know to play 
a C Major chord on top of a full G Major chord.
C
G

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