When you're in the key of C major and you use chords from C Dorian, Phyrgian, Lydian, Mixolydian, Aeolian, and Locrian. Why does it sound acceptable to use those chords, and does it work with all chords from those modes and can any mode be used?


It might be useful to think about your question a different way. Rather than trying to classify chords according to which modes they are in, forget about "modes" and/or "keys" and just consider the root progressions of successive major or minor chords. There are three basic groups, when the root moves up (or down) by the interval of a second, a third, or a fourth.

The root interval of a fourth produces a "dominant-tonic" or "tonic-dominant" harmonic progression.

The root interval of a third means that the two chords share some common tones, since the chords are themselves constructed by stacking intervals of a third.

The root interval of a second doesn't have such a clear cut function, but it can be an effective part of a longer progression. One example is the interval of a second creating a "secondary dominant" of the following chord - for example progression like C - Dmin/Dmaj/Dbmaj - G - C or even C - B - Emin (as in the start of Mendelssohn's "wedding march", in the key of C)

The first chord of each musical phrase can have almost any (or no) connection with the chord at the end of the previous phrase, so long as the following chords move towards re-establishing a connection that the listener can understand.

In the renaissance period, using meantone temperament, composers didn't think so much in terms of "keys" as in terms of "the set of major and minor chords which were in tune in the given temperament". A chord progression (in the nominal "key" of G) like G - F - C - Am - G - Eb - Bb - C - G - D - G (as used by William Byrd, for example) makes good musical sense, whether or not one gets tied up in knots trying to make it fit into any particular "theory" of harmony.

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Modal interchange is typically a way to simplify looking at chords outside of a scale/key. It's not that it's the only way to view the chords and typically that is far from true, but it gives the non-dictation/chromatic a simple context in a parallel scale/mode. There are two main phenomena which allow this to be extremely common, which are common tones in the chords/scales and chromatism.

Even when considering the furthest you can be away from C Major which is C Locrian, you still have 2 notes in common which are C and F. It's not a lot in this specific case, but if playing an F minor chord in C major you would recoginze that you could play a C Locrian (or F Phyrgian) scale over that chord and give your progression a very different flavor while using the common tones to keep you from going too far outside the key/scale you are in. The chord itself F minor is pretty close to an F major chord, just with the third lowered a semitone and that difference while being pretty big adds a lot of flavor which goes into the next topic of chromaticism.

The chromatic opportunities that can be achieved in modal interchange are what most people use modal interchange for, and really helps make progressions more interesting. For example, in one of my favorite progressions I - ♭VI - IV - V, while you can look at it as simply borrowing the ♭VI chord from C minor (Aeolian), the voice leading inside the progression is much more interesting as seen below:

V:1 clef=treble
"I"[C E G] "bVI"[_A C _E] "IV"[F A C] "V7"[G B D F]

As for the question does it always "work", the answer is simply no as not even every progression you make with only diatonic chords "don't work". If you keep the two ideas I stated in mind of common tones and it will typically work, however you still need to see and hear what you do and the effect it has on the progressions.

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  • IS there anyway you could put this in more of laymen terms? i get what your saying about the common tones, chromatism, but i didnt really get the last paragraph you wrote. That was about if they dont work all the time or not. So if im getting it right, modal interchange, is an out of the box approach of looking at other scales and modes that have some slight or drastic chromatic variations? – Janice Cee Oct 5 '16 at 0:47
  • @JaniceCee in general, there is no right and wrong or "working" and "not working" in progressions as every combination can be used to portray a certain effect so you can't really judge progressions in that light. However there are certain progressions such as the diatonic progression ii-I-viio-iii which would sound rather odd to most. Likewise if you just pulled out random modal interchange progressions like #vio-bII-bVII-I it would also sound rather odd because you're not really thinking about the line and what you are doing you're just pulling out random chords. – Dom Oct 5 '16 at 1:23
  • Oh ok i get it now, so basically i can use any chord in the chromatic scale to great effect as long as i use it in a good and solid chord progression. Re-establishing the key im in after using some chords that didn't belong in the key in the first place. I can also as well, change any minor chord to major,and change any diminshed chord to minor or even major,and vice versa, as long as the chord progression is solid, each chord i choose can be replaced with a different chord with the same root. So whichever mood i want to convey i could replace any chord with different one with a shared root? – Janice Cee Oct 5 '16 at 10:13
  • @JaniceCee you're mostly there I'm just going to clarify a few points. You make good progressions by having good voice leading and a clear direction to where your progression is going. As long as you keep those two things in mind in your progression should be fine. – Dom Oct 5 '16 at 11:13
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    Do get away from the idea that a key, mode or scale is a restriction. It can be a framework on which to hang more colourful 'chromatic' notes and chords. Or it can just be a description of what's going on at that point in the music. It doesn't in any way tell you what you are ALLOWED to write or play. – Laurence Payne Feb 6 '18 at 13:08

I wonder whether you mean what you've written. Dom has explained perfectly well, but did you really mean C Ionian, C Dorian, C Phrygian, etc.,all based on 'C', but all actually belonging to completely different keys.

For example, C Ionian has C,D,E,F,G,A and B, whereas C Phrygian has C,Db,Eb,F,G, Ab and Bb, and C Lydian has C,D,E,F#,G,A and B. So, between all the modes of C - all 7, making chords which come from each mode, there is just about every chord known to man available, from all the different notes!

So - if as you say, you're playing in C major, the opportunity to play most of these chords is very slim. Dom has explained how they could fit, but I think you actually meant the chords of C Ionian, D Dorian, E Phrygian, etc., which are the same chords for each - made from the same 7 notes. Since there is now a finite number of chords, each triad containing notes from the parent major key of C, it makes it easy to understand how, when you're playing in the key of C major, that the modes and chords from that parent major will fit.

NOTE: the terminology is confusing. C Dorian contains the notes from Bb major,(centring around C), whereas the Dorian OF C contains the notes from C major (centring around D)

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  • So techinally all of these modes, are based on altered variations of scales that can be composed using the chromatic scale, some got flat notes and some got sharps. So i can replace any chord with another chord if i wanted to? like a I-vi-VI-V in c major, i could replace the c major with a diminshed and the a minor with an A major and the f major with a f minor and the g major with a g minor, there shouldnt be any rules against it right? IF i want a certain mood i should be able to do it, maybe id have to establish the key first then do it, but it should be plausible at the least. Am i wrong? – Janice Cee Oct 5 '16 at 10:24
  • @JaniceCee - Need to get one thing straight! The 'rules' are man-made to help guide us through. They are certainly NOT 'laws'. As such, anyone can do whatever they want, musically. It won't ever be 'wrong'. It may (or may not) sound bad, but it will depend a lot on its context.What you're saying is can you have I-vi-IV-V in , say, C, and play a different chord that is C based, another different for the Am, another instead of F, but still IV rooted, etc.I think. Yes, of course. BUT - the proof's in the pudding. If it sounds good, it usually is, and vice versa. The substitution of different (con – Tim Oct 5 '16 at 10:38
  • t) chords , i.e. C min for C maj is something that happens frequently. Often, the reasoning behind it is 'using parallel key' notes/chords, rather than the way you describe, changing the mode, but keeping the root note, although to a degree, it comes down to the same idea. So, in C, C, Dm, Em, F, G, Am Bo are used, and from parallel Cm - Cm, Do, Eb, Fm, Gm, Ab, Bb will be the most used. D maj comes into play from 'it's the dominant of the dominant' but could also be construed to be from C Lydian, if you prefer. Like Emaj, as the dom of Am. Almost anything can be justified in musical terms... – Tim Oct 5 '16 at 10:46

When looking for a new, interesting harmonic colour in a piece of music, we don't go through a catalogue of 'permitted' modal interchanges. We MIGHT think 'let's try this chord shape shifted up or down a step'. Or perhaps 'let's try this chord with one (or more) notes slightly shifted'. Or even 'what's the GREATEST contrast I can find to the home chord?' (funny how often an F♯ chords gets thrown into a C major passage, purely for shock value :-) )

Then the sort of theorist who's uncomfortable with anything being 'out of scale' starts looking for a way to make these chromatic chords not REALLY chromatic, but sort-of extended diatonic. And he can usually find one.

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  • Ok, let's hear Barry Harris' postulation? Sounds interesting. You could present it as a new question within the SE rules by asking "BH says xxxx. Is this just a case of 'you can concoct a reason for ANYTHING' or is it valid?' – Laurence Payne Dec 31 '19 at 23:05
  • Sounds plausible. The question really has to be - Can you suggest a set of chords that CAN'T be given a justification? – Laurence Payne Jan 1 at 0:19
  • Might be conceptually satisfying. Musically though? The top floor of Tate Modern isn't my favourite place. – Laurence Payne Jan 1 at 1:38
  • Ah, you just don’t get it. I actually like the sound of F# over C, it’s always been very fascinating and only recently I’ve found ways to handle it with some kind of a framework so I can find related sounds. You can throw all that in the chromatic bin if it doesn’t feel worth further contact. – piiperi Reinstate Monica Jan 1 at 1:49
  • I quite like it too. And, having done it once in a piece, it obviously makes sense to do it, or something like it, again. But is that quite what we're talking about? – Laurence Payne Jan 1 at 2:04

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