(image taken from: www.world-of-songwriting.com)
The circle of fifths plays a very
important role in many aspects of western music. It sets the order to our key signatures. For those who are new to this concept, the
key of C major has no sharps or flats.
If we ascend five notes counting C as one (within the key of C) we reach
G. The key of G major has one sharp
(F#). If we ascend another fives notes
counting G as one (within the key of G) we reach D (two sharps) and so on. Descending from C in the same manor derives
the flat keys in order. The same is true
of the minor keys aside from the fact that A minor is the starting point (no
sharps or flats).
In addition, the circle of fifths
plays a major role in harmonic motion.
The most significant harmonic motion in western music is the cadential
motion from V to I. Most tonal music
travels on a harmonic path that eventually ends with this cadence. The V chord contains two elements that cause
a musical tension that our ears automatically wish to resolve (to the I
chord). First, the third interval of the
V chord is the leading tone of the key.
Our ears tend to want to resolve this pitch to the tonic. In addition, the tonic of the V chord is one
step away (within the circle) from the tonic of the I chord (the key). This means that the seventh of a V7 chord is
the flat version of the pitch that creates the difference between the key
signature we are in (I) and the next key signature in the circle (V). If that pitch is raised half a step we are
now in the next key of the circle (V becomes I). When that pitch remains lowered our ears perceive
a flat leading tone that does not resolve to a nonexistent key within the same
chord that contains the actual leading tone is the leading tone of the actual
key.
Simple forms of music capitalize on
this harmonic relationship by making it the only component of harmonic
motion. This is true in both major and
minor keys, however, I will focus my explanation on major keys for the sake of
simplicity. Many pop, rock and folk
songs only contain the chords I, IV and V.
The IV chord is not only a fourth above the I, but also a fifth below. Traveling from the I to the IV creates a fake
sense of cadential V-I movement. This is
followed by movement from the actual V back to I. Another option is to travel from I to
ii. The ii chord is a fifth above the V
chord. Therefore a ii-V-I movement
creates a sense of falling fifths. This
sense can be further expounded by use of the vi chord. The vi chord is a fifth above the ii
chord. A I-vi-ii-V-I progression creates
an even longer sense of falling fifths.
More complex forms of music use
this fifth relationship to temporarily travel to other key centers. These are the types of progressions that are
found in soul, gospel and jazz music. I
will discuss them in next week’s blog entry.