Other Triads

So far we’ve discussed I, V, IV, and ii. Now we can talk about the rest.

Leading-Tone Triad

The basic traits:

  • Diminished in both major and minor. (Remember the accidental for the leading-tone in minor!)
  • Appears only in first inversion: viio6. (Most stable in this form.)
  • When part writing, double the bass (the third, Re).
It most often appears in the following progression: I-viio6-I6 (also I6-viio6-I).
  • Bass: Do-Re-Mi
  • Upper voices:
    • Mi-Re-Do
    • Do-Ti-Do
    • Sol-Le-Sol
The book also mentions using it as a replacement for V (dominant substitute).
Finally, the book also mentions the leading-tone cadence. This is an awesome cadence from Medieval and Renaissance music that does not appear in the music we are studying.

Submediant (vi and VI) and Mediant (iii and III)

These two chords can appear in a few different ways:

  • Tonic Prolongation moving to a Predominant
    • I-vi-IV-V
    • I-iii-IV-V
  • vi can appear as a predominant itself by moving straight to a dominant
    • I-vi-V
  • vi can appear as a tonic substitute, which requires specific voice-leading work.
    • V-vi and V-VI (Deceptive cadence)
  • iii as “Dominant as Apparent Mediant”
    • I’ve seen two of these in my life, both in minor (III+6-i).
    • Basically a iii chord in first inversion (sol in Bass) functioning as a dominant.
    • This is so rare that I’m okay with you forgetting about this.
In general, vi is a very useful chord, having three different ways to use it. It is very common in rock and popular music. See Axis of Awesome. While iii is used in current tonal music a little, it is so rare in the music we are studying that I would prefer not to mention it. I will talk a little about III in minor below. In the end, part write them using the 3 Basic Movements. The only exception is V-vi which requires that we double the third in the vi chord. Everywhere else you will find vi, you will double the root.

Subtonic (VII)

The major triad built on the subtonic in a minor key always appear with III in minor. These two chords are common together, because III is the chord that matches the relative key (Say in C minor, III = E flat major.). And V in the relative major is the same chord as VII (V in E flat major = B flat major. VII in C minor: B flat major.) So using these two chords is like a short modulation to the relative major for a few chords, but returns to the original key by the next cadence.

Some Recommendations

  • Learn about viio6. This chord is common and useful, and a little tricky. Double the bass: the third.
  • Remember to use your 3 Basic Movements for the other chords, because they usually happen in root position.
  • Learn to part write the deceptive V-vi. This is very tricky and easy to forget. Double the third in vi after a V.
  • Forget about iii in major keys for this class. Use iii in your own music, if you use Roman numerals to help you compose.