The Complete Idiot''s Guide to Music Theory

Diminished Chord Notation
Example
diminished
C diminished
dimin
C dimin
dim
C dim
º
Cº
Augmented Chords
An augmented chord is like a major chord with a raised fifth; thus an augmented
chord consists of a root, a major third, and an augmented (raised) fifth. This is
sometimes notated 1-3-
5.
For example, the C augmented chord includes the notes C, E, and G
.
Here’s a quick look at how to build augmented chords on every note of the
scale:
While it’s important to learn about diminished and augmented chords, you won’t
run into too many of them, especially in popular music. If you base the root of
your chord on the notes of a major scale, as you’ll learn in Chapter 10, only 
the seventh degree triad forms a diminished chord. (Triads based on the other
degrees of the scale form major or minor chords.) There is no augmented chord
found on any degree of the major scale.
Note
Augmented triads.
There are many different ways to indicate an augmented chord, as shown in the
following table:
Notation for Augmented Chords
Augmented Chord Notation
Example
augmented
C augmented
aug
C aug
+
C+
Did you spot the double
sharp on the fifth of the B
augmented chord in the
illustration of augmented
chords?
Note

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Part 3:
Tunes
116
Chord Extensions
Chords can include more than three notes. When you get above the basic triad,
the other notes you add to a chord are called 
extensions.
Chord extensions are typically added in thirds; so the first type of extended chord
is called a 
seventh chord 
because the seventh is a third above the fifth. Next up
would be the ninth chord, which adds a third above the seventh … and so on.
Chord extensions are nice to know, but you can simplify most pieces of music
to work with just the basic triads. The extended notes add more color or flavor
to the sound, kind of like a musical seasoning. Like a good meal, what’s impor-
tant is what’s underneath—and you can always do without the seasoning.
So if you see a piece of music with lots of seventh and ninth chords, don’t panic—
you can probably play the music without the extensions and still have things
sound okay. Of course, for the full experience, you want to play the extended
chords as written. But remember, the basic harmonic structure comes from the
base triads; not from the extensions.
That said, it helps to have a full understanding of extended chords, just as a
good chef must have a full understanding of all the different seasonings at his or
her disposal. That means you need to know how to build extended chords—so
you can throw them into the mix when necessary.
Sevenths
The seventh chord is the most common chord extension—in fact, it’s so com-
mon that some music theorists categorize it as a basic chord type, not as an
extension. In any case, you need to be as familiar with seventh chords as you are
with triads. They’re that important.
Creating a seventh chord within a specific key or scale is normally as simple as
adding another third on top of the fifth of the base triad. This gives you a 1-3-
5-7 structure—the equivalent of playing every other note in the scale.
There are actually three basic types of seventh chords: major, minor, and domi-
nant. Major and minor seventh chords are kind of sweet sounding; the domi-
nant seventh chord has its own internal tension.
Dominant Sevenths
The dominant seventh chord—sometimes just called the “seventh” chord, with
no other designation—takes a major triad and adds a 
minor
seventh on top. In
other words, it’s a major chord with a lowered seventh; the chord itself consists
of a root, major third, perfect fifth, and minor seventh. This is sometimes
notated 1-3-5-
7.
For example, a C7 chord includes the notes C, E, G, and B
.
The dominant seventh chord is an especially important—and frequently used—
extension, as this is what you get if you play a seventh chord based on the fifth
(dominant) tone of a major scale. As you’ll learn in Chapter 10, the dominant

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Chapter 9:
Chords
117
chord is frequently used to set up the tension leading back to the tonic chord;
when you add a seventh to the dominant triad (with its mix of major triad and
minor seventh), you introduce even more tension to the music. Here’s a quick
look at how to build dominant seventh chords on every note of the scale:
Dominant seventh chords.
There’s really only one way to notate a dominant seventh chord: by placing a sin-
gle 7 after the name of the chord. For example, you notate a C dominant seventh
chord like this: 
C7.
Major Sevenths
The major seventh chord takes a standard major chord and adds a major seventh
on top of the existing three notes. This gives you a chord consisting of a root,
major third, perfect fifth, and major seventh. For example, a C Major 7 chord
includes the notes C, E, G, and B.
Here’s a quick look at how to build major seventh chords on every note of the scale:
Major seventh chords.
There are several ways to indicate a major seventh chord, as shown in the follow-
ing table:
Notation for Major Seventh Chords