How should I comprehend Modal Mixture?

Question

I’m studying the concept of modal mixture and there’s one thing that I immediately got curious about.

Supposedly, the majority of POP music (rock, hip hop, r&b, country, etc) is a mixture of Major and Minor Keys. But Mixolydian and Lydian are the first introduction of a flat and a sharp. Using C Ionian as the “root mode”, C Mixolydian adds Bb and Lydian adds F# (aren’t these also technically the F Major and G Major keys?) Adding on one more flat/sharp, you get C Dorian (which is also Bb Major?) And then, there is no corresponding mode for D Major? After all of these we finally get to Aeolian with 3 flats which is Eb Major.

So technically, if a song is “in C Major (Ionian) & C Minor (Aeolian)” through the use of say Bb and Ab chords, isn’t it also “in Mixolydian and Dorian”? Wouldn’t that also make Mixolydian, Lydian, and Dorian “more consonant” than Aeolian if it’s exactly the same concept as modulating around the circle of fifths?

Answer 1

"Modal mixture" is not the presence of multiple modes within a piece. The term refers to borrowing harmonic elements from the parallel major or minor of the predominant key.

For example, the current key is C major, but an F minor chord appears: say, in a harmonic progression C F Fm C. The presence of the F minor harmony is often explained by considering it as "borrowed" from the key of C minor.

Answer 2

I tend to think of "modal mixture" in the following manner. In any key, one can play any chord if it sounds good. There are some chords that are used much more commonly than others. For example, in the key of C major, the subdominant chord is F major; sometimes an F minor chord can sound particularly appropriate. If this F minor chord is used similarly to an F major chord, it's called (inappropriately as mentioned in other answers) a "modal mixture." A chord that's diatonic to the minor mode on the same tonic (a chord from C minor used in C major) is the "mixture." One could also use a major chord in a minor key for example. "Besame Mucho" has a pattern i-iv-V-i (with a few non-chord tones) followed by I-iv-V-i; the use of the major tonic gives a bit of "color." The I or i both act as the tonic in these phrases.

Answer 3

The 'modal mixture' description is fairly inaccurate! Yes, in a lot of songs, there's 'borrowing' - using notes/chords from the relevant major/minor keys with the same tonic. As in using notes/chords from Cm whilst in the C major key. Very common. And theory does its best to explain the phenomenon with the term parallel keys.

Take that a little further, and we find modes cropping up, in the same sort of way. So, a piece in C major may have notes/chords found in C Mixolydian, or C Dorian, for example. All the theory is trying to do is explain, best it can, where these extras come from, and why.

My take to my students is slightly different: any note, in any key - as long as you know what you're doing, and it sounds good...

Answer 4

If a piece is 'in' C major, along with the chords made from the notes of the C major scale you can mix in those made from C minor, and label them as 'modal mixture'. The most frequent 'borrowing' is probably iv, in C major that's the F minor chord. It also provides an excuse for bVII, the B♭ major chord, which can be hard to explain in functional harmonic theory.

'Modal mixture' is a subset of a wider musical principle: 'Chromatic chords are OK'. Try to free yourself from the idea that diatonic notes/chords are 'correct' and anything else needs a special excuse. Real music managed this hundreds of years ago!