16-2 FOUR STEP PROCESS
3. Most Common Modulations.
The two most common modulations are from a Major key to its dominant key (C Major to G Major) and from a minor key to its relative Major key (C minor to Eb Major). Modulation is usually accomplished by use of a pivot chord. A pivot chord is a chord that is common to both the original key and the new key.
a. There are three possible pivot chords between a Major key and its dominant key. Figure 16-4 shows the three possible pivot chords between the keys of C Major and its dominant, G Major.
Figure 16-4. Possible Pivot Chords Between Major and Dominant Keys
b. There are four possible pivot chords between a minor key and its relative Major key. Figure 16-5 shows the four possible pivot chords between the keys of C minor and its relative Major, Eb Major.
Figure 16-5. Four Possible Pivot Chords Between Minor and Relative Major Keys
4. Four Step Process.
Common chord modulation involves a four-step process: establish the original key, change the key, establish the new key, and return to the original key.
5. Establish The Original Key.
The first step of modulation is to establish the original key or tonal center. The original key is the beginning key and is usually the ending key. The original key must be firmly established. The following devices are important to establish the original key:
6. Change The Key.
The second step is a change of key that occurs by moving away from the original key to the new key while still retaining the original key signature. This is frequently signaled by the use of an accidental (chromatic alteration) and a chord diatonic to both the original key and the new key. A pivot chord is a chord common to both the original key and the new key. For example, the tonic chord in C Major could be used to modulate to G Major. The tonic chord in C Major is the same as the subdominant chord in G Major. The C Major chord acts as a pivot chord (or connecting chord) between the two keys. It has two functions since it is analyzed as the tonic of C Major (original key) and as the subdominant of G Major (new key). The double function should be shown in the analysis. Two levels of symbols are used in analyzing modulation. Figure 16-6 shows pivot chord modulation.
Figure 16-6. Pivot Chord Modulation
7. Establish New Key.
In the third step, the new key must be established. This is usually accomplished by a strong cadence.
a. Step three of the modulation process is signaled by the appearance of a modulating tone. An accidental from the new key is introduced. This accidental marks the entry into the new key. In shifting from a Major key to its dominant, the modulating tone is the new (raised) seventh scale degree. This new raised seventh scale degree now becomes the leading tone in the new key. Figure 16-7 shows the modulating tone (F#) when modulating from C Major to its dominant key of G Major. The F# is the leading tone in the key of G Major.
Figure 16-7. Modulating Tone
b. A strong cadence in the new key distinguishes between a true modulation and the momentary chromatic change caused by a secondary dominant chord. Measures three and four of Figure 16-8 show a cadence reinforcing the new key of G Major.
Figure 16-8. Cadence in New Key
8. Return to Original Key.
In the fourth step, return to the original key. This modulating process can move through many keys and then back to the original key or simply to the new key and then back to the original key. A return to the original key is not, strictly speaking, part of the modulation. However, since the return to the original key almost always occurs at some point after a modulation, it needs to be understood.
a. The main elements of the return to the original key are:
b. A simple return to the original key can be accomplished by beginning the next phrase with a I-V-I progression, or with some other strong basic progression in the original key. Figure 16-9 shows a I-V-I progression establishing the key of C Major.
Figure 16-9. I-V-I Progression
c. The return to the original key occurs in the reverse order of the modulation. The reverse steps are:
Figure 16-10 shows a return to the original key through a reversal of the modulation process.
Figure 16-10. Return to Original Key by Reverse Modulation
|David L. Heiserman, Editor||
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Revised: June 06, 2015