Lesson 11 Root movement by third

Lesson 11 Root Movement by Third

Part I - Root movement by third

The final category of root movement is that of a third.
This gives opportunity for many common tones among chords separated by a third.   For example:

      C - E - G
A - C - E
This is true for ANY two chords where the root is a third apart.  This means that when voicing the chords, two voices can hold the same pitches while the other two voices change around them.

Fig.1 two examples of root movement by third in C Major

Listen:

In the first example, the I and vi chord are separated by a third.  In the second example, the I chord and the iii chord are separated by the third.

Part II - The subtonic triad
This triad is most often found in the minor chord progression in the iteration: i-VII-III-VI-ii°-V-i
Here it is in c minor:

Fig.2 the Subtonic triad in c minor.

Listen:

Lesson 10, Root movement by second

Lesson 10 Root movement by Second

Part I - Progressions
Chord Progressions that use root movement by second:

I-ii-V-I                                         I-IV-V-I                                            i-iv-V-i

In each of these progressions, the underlined chords have roots that are a second apart.
Root movement by 2nd is one of the more important types of progressions because it creates the best indicator of key signature. The I-ii-V-I progression.  This will come in handy later when we discuss key change techniques.

You can see that the I and the ii chords have a root separated by a second.

Fig.1 Root movement by second I-ii-V-I

Listen:

Part II - Deceptive cadences
A deceptive cadence is that which ends on the VI chord. The I chord and the VI chords have two common tones  e.g.        C - E - G (I in the key of C)
                                 A - C - E       (vi in the key of C)
Thus, when writing a progression, the vi chord can be a substitute for the I Chord.

Fig.2 Root movement by second I-IV-V-vi

Listen:

This last example is simply root movement by second, not examples of deceptive cadences.

Fig.3 more examples of root movement by second

Listen:

Lesson 9 root movement by 5th

Lesson 9 - Root movement by 5th

Part I- Perfect authentic cadences

These are known as Perfect Authentic Cadences.  They are Authentic cadences because they are V-I, and they are perfect because the root of the chords are in the bass. There are different types of cadences that will be discussed later.

Fig.1 Perfect authentic cadences in C Major.

Listen:

 Fig.2 Lack of common tone in root movement by fifth.

Listen:

Notice that in the previous example there are common notes from chord to chord.  This is good voice leading practices because the singers will be less likely to miss the note. Because they are singing the same tone from chord to chord.

In Fig.2, however, each new chord every voice has a new pitch to sing.

 Fig.3 change of structure from chord to chord 

Listen:

Changing the structure from Chord to chord is useful to avoid awkward leaps and bad voice leading.  as demonstrated above in the first example, the structure is close in the first chord (V) and open in the second (I).  the reverse is shown in the example on the right.  

Part II - Plagal cadences

a plagal cadence is the subdominant (IV) chord leading to the tonic (I) chord

Fig.4 Plagal cadence in C Major

Listen:

 Fig.5 Authentic cadence with plagal extension.

Listen:

As demonstrated in the example above, the plagal cadence is most commonly an extension to the authentic cadence.  And is most commonly found at the end of a piece.

Part III - Half cadences

Fig.6 Half cadences

Listen:

A half cadence is a cadence that ends on the dominant (V) chord