In this post we will be looking at some practical uses for modal interchange. First of all, what is it? This is a technique that consists in temporarily borrowing chords from a parallel tonality or mode that shares the same root without abandoning the established key.
Using this technique is a great way of adding color and variety to chord progressions. You can look at it as a way of working with temporary modulations that introduce chromaticism from parallel tonalities to the tonic center you are working on and once we have established the tonal or modal centers that we will be using, we will know which chords and pitches are available to us and use those. Here is a melody in F Mixolydian from the Bb major key center, and with borrowed chords from F Aeolian, in the key center of Ab major:
You can also start with a melody that uses tones from the keys you choose to use for modal interchange. Automatically, you may be defining the places where the borrowed chords will be used. First the melody and then with the chords:
Remember that as long as the borrowed chord accommodates the melodic gesture you don’t necessarily need to change the notes in the melody. In this example you will hear that the melody stays in the same key, in C Dorian, while I’m using borrowed chords from C Lydian:
Although the most commonly used borrowed chords originate from the major and/or minor parallel modes, including the respective harmonic and melodic minor as well as symmetrical scales sharing the same root, there is no reason to limit yourself to these since the premise is that modal interchange can occur with any mode that shares the same root – i.e. E Dorian and E major:
Another use for borrowed chords is to use them as passage or link between two diatonic chords. In this case, we will be using an Ab major chord from parallel key of C minor as a passage between F major and G major chords from the C major tonality:
Going from one parallel mode to another may be accomplished by directly introducing the borrowed chord in the chord progression, by using common pitches shared between the respective parallel modes and using chord transformations to smooth the process of modal interchange:
Oscillating between E dorian and E lydian
Using a chord progression where C major is transformed into C+ or Ab+ and then borrowing chords from C minor using common pitches to transition between chords: C – C+ – Fm – Dº – C
In sum, modal interchange chords can be used in different ways, such as adding color by introducing chromaticism in the harmony and/or melody; as a tool for reharmonization; as pivot chords for modulation; or as a link between two diatonic chords.
Remember that when using this technique, it is important to make sure that the original key is clearly established before and after using borrowed chords since we are working with temporary modulations.
You can use the thought process and materials involved in the use the modal interchange approach to make definite modulations, although technically it is no longer modal interchange per se, since you are not borrowing chords and then returning to the initial tonality or modal center. You are only modulating to a different key.
I hope that this technique opens up other harmonic and melodic possibilities for you to explore in your music. Experiment with it and find your own ways of using this technique and then leave a comment below so we can learn from it!
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