This blog post is part of a series about the musical theory which SoundPrism is based upon. Check out the previous one: SoundPrism Cadences: Part I
In my last post I talked about pure major and minor cadences. I compared a cadence to a pendulum and showed that there are two basic types of cadences: The „pendulum movement“ and the „circular movement“ (Figure 1).
Figure 1: The circular and the pendulum movement
Today I am going to show how to improve these cadences by replacing one or two chords by so called substitutes.
Substitutes are chords that can replace other chords without destroying the character of the cadence. You might be asking yourself: „Ok, and which chords can I substitute with which one?“
Music theory literature offers complicated rules like „you can replace the „I“-chord by the „iii“-chord or „iv“. For people who didn’t already have one or two years of harmony theory education such rules sound quite complicated and are difficult to remember. With SoundPrism these rules can be explained much clearer.
There are several possibilities to substitute chords by other ones. The most important chord substitute is the so called „parallel chord“ (Please do not confuse it with the „parallel key“).
As you can see in Figure 2 below: In SoundPrism the tonic T and its parallel chord Tp are next to each other. The parallel of the tonic is called tonic parallel (Tp).
Figure 2: The major tonic and its parallel chord
Knowing this you are able to change a simple major pendulum cadence by replacing the tonic by its parallel chord as shown in Figure 3:
Here the cadence starts at the major tonic T, then moves to the dominant D, but does not return to the tonic T but instead to the tonic parallel Tp. After that the pendulum movement is finished normally: The pendulum moves to the subdominant S and returns to the tonic T.
Figure 3: The pendulum movement with substituted tonic
In SoundPrism the cadence looks like this:
Video 1: The pendulum movement with substituted tonic in SoundPrism
This cadence is the basis of many pop and rock hits of the recent years. The australian comedy band Axis of Awesome has shown this with their „Four Chord Song“.
Video 2: Axis of Awesome‘s „Four chord Song“ uses the cadence shown in Figure 3
Differences between major and minor
The previous paragraph was about the parallel of the major tonic. Now I am going to talk about the parallel of the minor tonic. In minor a tonic and a tonic parallel exist as well. The only difference is that the tonic parallel is located above the tonic. This is shown in Figure 4: Here the chord a-minor is the tonic t. And the chord C-major is the tonic parallel tP. Summarizing you can say that in SoundPrism the tonic parallel is below the tonic in major mode and above the tonic in minor mode.
Figure 4: The minor tonic and its parallel chord
Symbols of parallel chords
At the first look the symbols for parallel chords seem a little bit confusing. But there is a clear system, which can be summarized like this:
The symbol of a parallel chord consists of two letters. The first letters describes the original chord and the second letter the kind of substitution. The first part of the symbol tP for example shows, that the original chord is the tonic „t“. The second part, the „P“ symbolizes that the former tonic t has been replaced by its parallel. The parallel chord is a major chord. Therefore we use an uppercase „P“. In other words:
Major: To show that a major tonic T is substituted by its parallel chord you simply have to add a lowercase „p“ to the symbol T (see Figure 3) which results in the symbol Tp for the tonic parallel. The lowercase p illustrates that the tonic parallel is a minor chord.
Minor: To show that a minor tonic t is substituted by its parallel chord you simply add an uppercase „P“ to the symbol t. The uppercase P illustrates that the tonic parallel is a major chord.
Parallels of the subdominant and the dominant
The rules explained above also apply to the subdominant and the dominant. Thus if you have understood the major tonic and its parallel you have also understood the subdominant, the dominant and its parallel chords. :-)
Figure 5 summarizes all chords and its parallels for the keys C-major and a-minor. At this point it might be useful to emphasize that one and the same chord can have different symbols. In Figure 5 you see that the chord C-major is tonic T within the key C-major, and tonic parallel tP within the key a-minor.
Figure 5: Comparison of function symbols in SoundPrism for major and minor
Things to remember
The circular movement and the pendulum movement are the most often used cadence types.
To make cadences more interesting substitute chords by its parallel chords.
In SoundPrism the tonic parallel is below the tonic in the case of major keys and above the tonic in the for minor keys.
The same also holds for the subdominant and the dominant.
Next blog post
In my next blog post I am going to show additional examples for chord substitutes.