Some Messiaen-like Chords

I've always enjoyed Messiaen's chords without really knowing what's going on with them, so today I looked at an article about them and cooked up some chords of my own inspired by it.

The article describes the idea of taking a base chord and adding one or more "resonance notes" that are purely there to colour the sound. Of course, this is how jazz musicians think about chords all the time because really jazz after about 1945 has been predominantly non-tonal, or at least non-functional; just don't tell anyone at Berklee (that's a tale for another time).

The official recipe is: start with a 9 chord, i.e. 1 3 5 b7 9. Make it a sus 4, so now we have 1 4 5 b7 9. In fact this is a mode of the common pentatonic scale -- if 1=A, play E minor pentatonic and you'll get exactly those notes. This is very convenient for us guitarists, to whom this scale is an old friend.

Now add the b5 and 7 on top, so we have (top to bottom) 1 4 5 b7 9 b5 7. If you still think in terms of the V minor pentatonic, you can think of the 7 as "3 of V", i.e. the G# added to the E minor pentatonic, which is indeed the (major) seventh of A. Similarly, the "b5 of I" becomes that "7 of V", which in our example is D# (the major seventh of E). If this way of thinking doesn't help you, though, be sure to ignore it.

Well, that's seven notes so to play it as a chord we non-extended-range guitarists will have to make some modifications. What I did was first remove the root but keep the rest of the seventh chord : 4 5 b7. This is a pentatonic sound that's very consonant over either a minor 7 or dominant 7 chord at the root, and that you can move around to many other positions there or over a major 7. It's diatonic: it belongs to the world of tonal music.

Now I'm considering the 9, 7 and b5 as "resonance notes" that can be added to it. The 9 isn't terribly interesting in this context, since 4 5 b7 9 is just four of the five notes in a normal major pentatonic scale, shifted down a whole tone. This is a pretty common thing to play on a minor 7 or dominant 7 and is a very "inside" sound with no real tension. So we'll ignore the 9 and focus on the other two.

The results are dissonant and decidedly Messiaen-flavoured, with the same pitch collection producing very different sounds in different voicings:

This isn't systematic, just a few of the possibilities that seem to me to be guitaristic. I haven't gone into the way Messiaen used these at different transpositions over the root note but you can probably figure that out now I've said it -- if not look at Benitez's article, it's very clear. The tab is obviously just a suggestion -- some of these are more awkward than they look on paper, at least for me, so I might drop one or more notes in a real-life application.

Finally, of course you can start with any structure that makes sense to you instead of 7sus4, and add any "resonance notes" to it. This means this approach can yield every possible chord, which means it's not really a magic formula so much as a way of thinking about things.