Practical Music Theory unit 9: Chord motion in 4ths


  • Chord motion in 4ths

  • Motion in 4ths

    An important–even essential–point to understand about how chords work is that chords LOVE to change in fourths.  They don’t HAVE to change in fourths, but they very often sound like they WANT to change in fourths.  Here’s what I mean:

    When I say “a fourth” I am referring to an interval.  The word “interval” in music refers to the size of the leap from one chord (or note) to another.  If you look at the Table of Major Scales, you can determine the fourth by simply looking at the first step of the scale, and then looking ahead to the fourth step of the scale.  If you start on A, the fourth would be D.  If you start on C, the fourth would be F.

    Another way to phrase this same idea would be to say that D is a fourth above A, and that F is a fourth above C.

    Looking at this idea as it relates to chord progressions, the basic idea is that any type of A chord (A, A7, Am, etc.) is very likely to be followed by a chord that is a fourth higher, so some kind of D chord (D, D7, Dmaj7, Dm7, etc.). And just remember it is not a requirement that chords do this, it just sounds good when they do. Composers can play with this sense of “gravity” to create different effects of tension and resolution.

    Here’s a quick list of each note and the note that is a fourth above it. Look at the songs you already know how to play, and you’ll see this concept in action all over the place.

    A > D
    Bb > Eb
    B > E
    C > F
    C# > F#
    D > G
    Eb > Ab
    E > A
    F > Bb
    F# > B
    G > C
    Ab > Db

    The Lone Exception: Diminished chords.

    The one exception to this “rule” is with diminished chords, which simply like to resolve up a half step. Bdim wants to go to C, F#dim wants to go to G.

    “Circle Of Fourths” chord progressions

    You may have heard of the “circle of fourths” and/or the “circle of fifths” (which is the same thing in the opposite direction) as an essential concept in music theory. Quite frankly I’ve never found it all that useful beyond knowing which chord is a fourth away from whatever chord you’re on. But the basic idea of it is that you can start on any note, go up a fourth, and then another and another, and eventually you get all the way back to where you started.  If you started on C, it would look like this:

    C > F > Bb > Eb > Ab > Db(C#) > F# > B > E > A > D > G > C

    If you started, say, on Eb, it would look like this:

    Eb > Ab > Db(C#) > F# > B > E > A > D > G > C > F > Bb > Eb

    In many cases, you might see entire chord progressions, or large portions of chord progressions, that move entirely in fourths.  We call these “Circle Of Fourths” chord progressions.  One famous example of this occurs in Charlie Parker’s song “Confirmation,” which is actually just a variation of a 12-bar blues, but it contains this long sequence of chords to get from the I chord to the IV chord:

    Fmaj7 |  Em7b5  Am7  |  Dm7  Gm7  |  Cm7  F7  |  Bb

    Note that the first change, from Fmaj7 to Em7b5, is not a fourth, but it’s fourths the rest of the way through.  Pretty cool way to get from F to Bb, huh?

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