CHAPTER FOURTEEN

The Submediant and Mediant Triads

Overview

In this chapter we will study two additional secondary triads, the submediant and mediant. Both of them occur less frequently than the triads we have previously studied. Both are minor triads when employed in a major key and major triads when found in a minor key.

Due to the altered sixth and seventh degrees in the minor scale, two other versions of these triads are possible in a minor key. These chords are the vi⁰ (diminished) and the III+ (augmented) triads. Since the submediant and mediant are used very little in this manner, however, they are mentioned only in passing.

We will find that the submediant is employed in a variety of ways. It may progress to the supertonic, subdominant, or dominant, or to the mediant when the mediant is followed by the subdominant. We will see that one of the most effective uses of the submediant is the progression V-vi (or V-VI) at a cadence. The result is called a deceptive cadence.

In contrast to the submediant, the mediant is much less versatile. It most commonly progresses to the subdominant and first-inversion supertonic triads. Occasionally, this triad may progress to the submediant or the dominant.

Provided in this chapter are a number of musical examples which illustrate varied root movement involving the submediant and mediant triads. We will observe the submediant used in root movement by descending thirds, descending fifths, and ascending and descending seconds. We will also examine examples of the mediant progressing by descending fifths and by ascending seconds. In the

commonly used vi-iii-IV progression (VI-III-iv in minor), we will see both the submediant and mediant triads used in a combination of root movement by descending fourth and ascending second. We will also observe that ii (ii⁰ in minor) may be effectively substituted for the subdominant in this three-chord progression.

As we will note, both the submediant and mediant are usually employed in root position. They are used only infrequently in first inversion and rarely in second inversion. When the submediant and mediant are employed in first inversion, they generally follow a root position triad whose bass note is the same as that of their own first inversion note. Therefore, vi is normally preceded by I and iii⁶ by V.

In part-writing the submediant and mediant triads, new conventional procedures should be followed in certain circumstances. In progressions in which roots are a second apart and the soprano and bass move in the same direction, the third of the submediant triad must be doubled in order to avoid parallel octaves, fifths, and/or melodic augmented seconds. If the roots are a third apart, usually it is necessary only to hold the two common tones and move the other voice by step.