The Complete Idiot''s Guide to Music Theory

Chapter 16:Chord Substitutions and Turnarounds 209

Substitution Example (for the G7 chord)

Diminished chord a third above

Minor 7 chord a fourth below—

over the same root

The more interesting substitutions here are the first one and the last one. The
first substitution replaces the V7 chord with a IV chord; the use of the sub-
dominant (IV) chord results in a softer lead back to the I chord. The last
substitution uses an altered chord, so that you’re leading back to tonic with a
iim7/V—what I like to call a “Carole King chord.” (That’s because Ms. King
uses this type of harmonic structure a lot in her songwriting.) So if you’re in the
key of C, instead of ending a phrase with a G or G7 chord, you end with a
Dm7/G instead. It’s a very pleasing sound.

Functional Substitutions

Here’s something else to keep in mind. Within the harmonic context of a com-
position, different chords serve different functions. The three basic harmonic
functions are those of the tonic, subdominant, and dominant—typically served
by the I, IV, and V chords, respectively. But other chords in the scale can serve
these same functions, even if not as strongly as the I, IV, and V.

For example, the subdominant function can be served by either the ii, IV, or vi
chords. The dominant function can be served by either the V or vii° chords.
And the tonic function can be served by either the I, iii, or vi chords. All these
functions are shown in the following table:

Chord Function Chords

Tonic I, iii, vi

Subdominant ii, IV, vi

Dominant V, vii°

When you have a chord serving a specific function in a composition, you can
replace it with another chord of the same type. So if you have a IV chord, serv-
ing a subdominant function, you can substitute any of the other subdominant-
functioning chords—the ii or the vi. Along the same lines, if you have a ii
chord, you can replace it with either the IV or the vi.

The same thing goes with the other functions. If you have a V chord, serving a
dominant function, you can replace it with a vii° chord—or vice versa. And a I
chord, serving a tonic function, can be replaced by either a iii or a vi chord—
and also vice versa. It’s actually a fairly easy way to make some simple chord
substitutions.

Just in case you think you

found a mistake in the pre-

ceding table, the vi chord

can serve both the tonic

and subdominant func-

tions. It’s a very versatile

chord!

Note