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Part II: Triads and Inversions
We’ll start with a more refined definition of a triad
that was given earlier. Though a triad is built upon the tonic, mediant,
and dominant degrees of a scale, this only defines a triad in as of
itself. What about the specific sound and characteristics that makes up
the different types of triads?
First, recall the two intervals, the major third and the
minor third. All triads are built upon these two intervals. If you stack
them on top of each other, you will get a total of four different
combinations of triads.
Let’s analyze C Major below:
[Piano showing tones highlighted...staff next to it
indicating notes of the triad]
There are three tones that make up this chord. What is
the interval between the first tone and the middle tone (the one and the
three)? It is a major third. What about between the middle and the last
tone (the three and the five). It is a minor third. You will notice the
third is shared when making the comparison.
From this we can conclude that a Major chord is
composed of two stacked intervals. It contains a major third on the
bottom (hence the name “major chord”) and a minor third on top.
Let’s analyze a minor below:
[Piano showing tones highlighted...staff next to it
indicating notes of the triad]
In the same manner as before, we can identify the major
and minor intervals. Unsurprisingly, there’s a minor chord on the bottom
and a major chord on top. A minor chord is composed of a minor
third (bottom) and a major third (top).
We now have two very common chords in Western
music...probably the most common in the early era (besides perfect fifth
and fourths). However...we seem to have neglected 2 very important
chords both of which were considered to be quite evil by the church for
its horrid dissonance. Of course, not only is our own ear more in tune
to this sound, but in the older music systems, the notes actually
sounded different that they do on standard instruments today (see
section on temperament), and actually much more dissonant as well.
The first chord we will look at is the diminished chord.
It’s named this for two reasons. First of all, when we compare it to the
next chord, we will notice that it sounds a lot “smaller” and more
compact than it. The other reason has to do with the intervals it’s
composed of. A diminished chord is composed of a minor third on
the bottom and a minor third on the top. This makes a fairly dissonant
sound and is often used to create suspense or even make a very haunting
sound.
In comparison to the minor chord, we find it’s the same
except the 5th tone of the chord was dropped by a half step.
It was diminished in size.
The other chord is the augmented chord. An augmented
chord is composed of 2 major third stacked on top of each other. In
comparison to the major chord you can see that the fifth tone was raised
a half step. It was augmented in size.
The table below summarizes the triads:
|
Type |
Interval |
Symbol |
Example of Symbol |
|
Major |
M3, m3 |
M
(optional) |
C(M) |
|
Minor |
m3, M3 |
m |
cm |
|
Diminished |
m3,m3 |
˚ |
c˚ |
|
Augmented |
M3, M3 |
+ |
C+ |
Note 1: For Major, the “M” symbol is usually omitted but
you may see it occasionally.
Note 2: The letter of the major chord is usually
capitalized (e.g. C Major). Likewise, the minor chord is usually
uncapitalized. In this manner, since the diminished chord relates closer
to the minor chord than the major chord, the same notation is used for
the diminished as the minor chord. Major is closely related to augmented
and therefore the augmented chord is usually capitalized to make it look
similar to major. Also note that notation in general differs from place
to place, but you will find that the triad notation is fairly similar.
Inversions simply build upon the concepts discussed in
the previous section. A chord inversion is no more than a switching
around of the tones of a chord.
For example, let’s take C Major. C Major is composed of
the tones C E and G. This is how it looks on the keyboard and staff:
[Picture showing keyboard and staff w/ C Major]
Now these tones can be rearranged in more than one way
can’t they? The C Major you know and are familiar with (CEG) is what’s
called root position. Root position is any chord where the root
note of the chord is at the root.
Let’s take the C and move it to the top of the chord. We
now have E G and C. Still the same chord...but different sound and look.
We have just formed the first inversion of C Major.
[Picture showing keyboard and staff w/ C Major 1st
inv.]
Now that we have E G and C, let’s take the E and move it
to the top. Now we have the chord G C and E. This is the second
inversion of C Major. If you move the G to the top you are back with C
Major in root position again.
[Picture showing keyboard and staff w/ C Major 2nd
inv.]
Note that this does not mean the chord has a new root.
The root is still C, but the bass note is the third or the fifth. It’s a
precise distinction.
These chords are extremely useful for substitutions and
have a number of usages in chord progressions. Their usage is also
extensive in melodic compositions. Some of the most beautiful melodies
can be created with just 3 tones.
Notation of the inversions used in chord progressions
will be dealt with in the section on chord progressions (XII). Notation
of inversions used in chord symbols will be dealt with in section IX.
There is another sort of “inversion” you can make as
well, but it is more appropriately titled as an alternative voicing.
Once again we will work with C Major. You have the tones C E and G. How
about switching the E and the G around? Notice, this is not really an
inversion, it’s still in root position but the third and fifth tones
have been reversed. An inversion requires that the third or fifth of the
triad becomes the new bass note.
So it’s essentially just a different arrangement, or
voicing of the tones. This will become much clearer when you begin to
look at four-part writing in section X.
This section will be
updated soon with information on interval inversions.
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