25: Subdominant & Dominant
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Lesson 25: Subdominant & DominantThis lesson teaches the subdominant and dominant chord functions. This is part of understanding how the different diatonic chords "work" in chord progressions.
Before taking this lesson, you should know: the tonic chord function (Lesson 24: Tonic Function).
To review, the common major-key diatonic triads are:
I IIm IIIm IV V VIm
This lesson explores IIm, IV, and V.
The Subdominant Chords: IV and IIm
Subdominant function. A subdominant chord feels like you've moved away from the home chord. It's extremely common for the I chord to be followed by a subdominant chord.
The IV chord. "Subdominant" is just a name for "scale degree 4", so "the" subdominant chord is the IV chord.
The IIm chord. The IIm chord also has subdominant function, meaning that is has a "moved away from home" effect similar to the IV chord. Notice that two of the pitches (namely, scale degrees 4 and 6 of whatever key the song is in) in the IIm and IV chords are the same pitches. In fact, these two chords are pretty interchangeable. Reasons a song might choose one or the other include:
The Dominant Chord: V
Scale degree 5 is called the dominant; so, the V chord is called the dominant chord.
Dominant function. The dominant chord (the V chord) feels like it want to return to the home chord; it's extremely common for the dominant chord to be followed by the I chord.
The Typical Diatonic-Function Sequence
Since tonic "tends to go to" subdominant, and dominant "tends to go to" tonic, the most typical sequence of diatonic functions is:
Tonic -> Subdominant -> Dominant -> Tonic
This sequence has a conventional "advancing" ("moving forward") feeling. If a chord sequence reverses this order (tonic -> dominant, dominant -> subdominant, subdominant -> tonic), it tends to sound like it's retreating. That's how I describe it, anyway; but these effects are subtle and subjective. You should decide for yourself what you think the effects of different diatonic-function sequences are, by studying the sequences in various songs.
In fact, that's the subject of the next lesson, Lesson 26: Diatonic Function Analysis.