Borrowed Chords and Modal Interchange

So far, all our progressions stayed within a single scale: seven notes, seven chords. That's a solid foundation, but you've surely already heard, in a film score or a pop chorus, a chord that seems to come from somewhere else and suddenly gives you a shiver. Very often, it's a borrowed chord: a chord taken from the key that has the same tonic, but the other mode.

Minor slipping into major

Let's listen first. Here's a progression in C major: C, F, then a chord that doesn't belong to this key, Fm, and finally back to C.

The move from F to Fm changes only one note: A drops a half step to A♭. That small drop gives a soft, melancholy color, like a cloud passing in front of the sun. Then A♭ drops another half step to G, the fifth of C major, and home returns with a sense of nostalgia. Listen to the two chords separately, then to the descending line.

Where does this Fm come from? From the key of C minor, which has the same tonic as C major. C major and C minor are called parallel keys. Since they share their home, you can move from one to the other for the length of a chord without losing your sense of the key. You'll also hear this called modal interchange or modal mixture.

What you can borrow

Compare the chords of the two keys. C major has C, Dm, Em, F, G, Am and B°. C minor has Cm, D°, Eb, Fm, Gm, Ab and Bb. Among the chords of C minor, four are used especially often in C major, because they sound rich without losing home.

These chords are written with a flat in front of the Roman numeral. ♭VI means the major chord built on the sixth degree lowered by a half step: in C major, the sixth degree is A, it becomes A♭, and the chord is A flat major. In the same way, ♭VII is B flat major and ♭III is E flat major.

♭VI and ♭VII, the epic sound

Now listen to the movement ♭VI, ♭VII, I. In C major, that gives you Ab, Bb, then C. The bass rises a whole step, then another whole step, and lands on the tonic with a lot of brilliance. It's an ending used a lot in film music, video game music and rock, whenever you want a triumphant arrival without going through the classic dominant.

Notice that the Bb chord replaces the dominant here. It has no leading tone, since B becomes B♭ in it, but the bass rising a whole step to the tonic is enough to create a strong return. The ♭VII to I movement is so common that you also find it on its own, alternating with the tonic: C, Bb, C, Bb, a loop that sounds open and a little rock.

In minor, ending on a major chord

Borrowing works in the other direction too. In a minor key, you can end on the major tonic chord, borrowed from the parallel major key. In A minor, that means ending on A major, with C♯, instead of Am. This final chord has a lovely old name: the Picardy third.

The effect is like a light switching on at the very end. You hear it in early music, but also at the end of film scores or melodic electronic tracks, when you want the last chord to sound like a victory or a moment of peace. Since it completely changes the character of the tonic, it's usually saved for an ending, not the middle of a loop.

Chromatic mediants, the sound of cinema

There's another family of chords from elsewhere, much loved by film composers. A chromatic mediant is a chord whose root is a third away from the tonic, with the same quality as the tonic, and which doesn't belong to the scale. In C major, the most common are E major, A major, Ab major and Eb major. The last two, as you may notice, are also among the borrowed chords.

Their secret: these chords keep a single note in common with C major, and the others move by a half step or a whole step. Between C and E, for example, E stays put, G rises a half step to G♯, and C drops a half step to B. The movement is tiny for your fingers, but your ear hears a spectacular change of light.

This loop doesn't resemble any of the progressions we've seen, and yet it stays coherent. It's the sound of many soundtracks, when the camera reveals a landscape or a character realizes something. In electronic production, these movements work very well with long pads and generous reverb, which give you time to hear the color change.

Where to place them

A borrowed chord stands out; that's the whole point, but it's also the risk. A few guidelines help you place it well. Use it toward the end of a phrase, in the third or fourth bar of a loop, so it sets up the return of the tonic. Surround it with chords from the key: one borrowing per loop is often enough. Finally, check that your melody and your bass follow it.

You now know which chords to choose. The next lesson looks at another question that often gets overlooked: how fast to change them.