MUS 112 Study Guide N (Chapter 14)
Submediant & Mediant Triads
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The submediant triad (vi or VI), though
occurring less frequently than those previously studied, is the most
versatile in terms of those triads to which it can relate.
In progressing toward the tonic, the submediant
triad is commonly followed by the supertonic (ii, iio),
subdominant (IV, iv) and dominant (V) harmonies.
The progression V-vi or V-VI is quite common.
Because the expectation of V moving to I is so compelling, V to the
submediant chord is commonly called deceptive; at a cadence
the progression is called a deceptive cadence.
The mediant triad (iii or III) is, in major,
the furthest away from tonic in the progression of root movement by
fifth. It is used considerably less than other triads.
The mediant triad usually progresses to the submediant
(iii-vi, III-VI) or to a subdominant function (iii-IV or ii6,
III-iv or iio6). Note that in both IV and ii6
(iv and iio6), the bass is the subdominant note.
Probably the most frequent use of the mediant is in a
progression of three triads vi-iii-IV (VI-III-iv). The
progression vi-iii is infrequent without the following IV or iv.
Root Movement by Downward Thirds: With the
inclusion of the submediant triad, it is possible to construct a
harmonic pattern based on root movement by thirds. Of all the
possible movements by thirds, the progression I-vi-IV-ii (in whole
or in part) is common. In vi- ii6, the bass
movement down a third produces an aural effect of root movement down
a third, as though it were vi-IV. The progression IV-ii is
also possible. V-iii is uncommon (deceptive).
Root Movement by Downwards Fifths: The most
useful progression from the submediant is to the supertonic, either
in root position or in first inversion. Progression from iii
to vi should be common, considering the root movement by fifth, yet
it is far less common than root movement by second, iii-IV.
Root Movement by Seconds–the Deceptive
Cadence: The deceptive cadence (V-vi) is one of the
most dramatic of any individual chord progression, for reasons
stated earlier. This progression may appear equally as well
within the phrase. Combined with nonharmonic tones, it can be
The most common use of the mediant triad, iii-IV, is
particularly effective in harmonizing the descending scale line 8 7 6
5. The roots of I-iii-iv-V in the bass produce a line in
contrary motion to the melody.
The vi-iii-IV Progression: in minor,
VI-III-iv. Having vi precede iii is uncommon unless IV
follows. Substitution of ii6 or iio6 for
IV after the mediant triad is possible because both progress to V
and they have the same bass note.
Inversions of the Submediant and Mediant
Triads: Submediant and mediant triads are infrequent in first
inversion and rare in second inversion. Each of the triads
usually appears in first inversion only when the root of the
preceding triad is the same bass note as the first-inversion
note. There are just two practical possibilities: I-vi6
Writing the Submediant and Mediant Triads:
Most progressions in root position can be written using conventional
procedures. When either triad is inverted, use the
conventional procedure for approaching and resolving the doubled
tone (contrary or oblique motion, if possible).
When roots are a second apart and the soprano and bass
move in the same direction, as in V-vi or vi-V, the conventional
procedure will not work because parallel 5ths, 8ths, and/or augmented
2nds usually result. In this situation: double the third in
the submediant triad. This procedure can be used in similar
situations where use of conventional procedures is awkward or
impossible. Doubling the third is especially effective when the
doubled note is the tonic, subdominant or dominant note of the key.
When the soprano and bass move in contrary motion, write the
upper three voices so they move in contrary motion to the bass.
When roots are a third apart the chords have two tones
in common. Usually it is necessary only to hold these two tones
and move the other voices by step. This procedure is useful in
the progression I-iii (i-III), I-vi (i-VI), IV-ii and vi-IV (VI-iv).
The mediant triad is used infrequently in inversion.
Should the melody line skip a third or more when the
roots move by third, there is no conventional procedure. Simply
make sure that there are no parallels and that the voices are in
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