Digital Sound & Music: Concepts, Applications, & Science, Chapter 3, last updated 6/25/2013
consider what kind of triad this would be in the key of D. It has the notes D, F, and A.
However, in the key of D, F should be sharp. D is not sharp in the triad II shown, so this is a
minor triad from the key of D. Triad III has the notes E, G, and B. In the key of E, G is sharp,
but in the triad III shown, it is not. Thus, the third triad in the key of C is E minor. Let’s skip to
triad VII, which has the notes B, D, and F. In the key of B, the notes D and F
are sharp, but they’re not in triad VII. This makes triad VII a B diminished. By
this analysis, we can determine that the sequence of chords in C major is C
major, D minor, E minor, F major, G major, A minor, and B diminished.
All major keys have this same sequence of chord types – major, minor,
minor, major, major, minor, and diminished. For example, the key of D has the
chords D major, E minor, F minor, G major, A major, B minor and C
diminished. If we do a similar analysis for the minor keys, we find that they
follow the pattern minor, diminished, augmented, minor, major, major, and
diminished, as summarized in Table 3.10.
Chord number Chord type if the triad sequence
comes from a major key
Chord type if the triad sequence
comes from a minor key
I major minor
II minor diminished
III minor augmented
IV major minor
V major major
VI minor major
VII diminished diminished
Table 3.10 Types of triad chords in major and minor keys
220.127.116.11 Chord Progressions
So what is the point of identifying and giving names to intervals and chords? The point is that
this gives us a way to analyze music and compose it in a way that yields a logical order and an
aesthetically pleasing form. When chords follow one another in certain progressions, they
provoke feelings of tension and release, expectation and satisfaction, conflict and resolution.
This emotional rhythm is basic to music composition.
Let’s look again at the chords playable in the key of C, as shown in Figure 3.35. Chord
progressions can be represented by a sequence of Roman numerals. For example, the right-hand
part of “Twinkle, Twinkle Little Star” in the key of C major, shown in Figure 3.23, could be
accompanied by the chords I I IV I IV I V I in the left hand, as shown in Figure
3.36. This chord progression is in fact a very common pattern.
Figure 3.36 “Twinkle, Twinkle Little Star” with chords as Roman numerals
You can play this yourself with reference to the triads from the key of C major, shown in
Figure 3.35. However, to make the chords easier to play, you’ll want to invert them so that the
Chords in a