The Submediant Triad

• The Submediant triad is built on Scale Degree 6.
• It is major in the minor mode and minor in major mode
• This chord's generic function is both predominant and tonic

Building a Submediant Triad

This triad is simple enough to build

In the Major mode

• Scale degrees 6, 1, and 3 (La, Do, Mi)
• The quality is minor

In the Major mode

• Scale degrees 6, 1, and 3 (Le, Do, Me)
• The quality is Major

Note that this is the first chord we have seen that is build on different absolute pitches for the two modes, major and minor.

Luckily, this changes nothing about how the chord functions! All of the rules about the chord are identical in both modes.

What Note Do You Double?

This chord follows the same doubling rules as any other chord when it functions as a predominant chord

1. Root position: Double the root (the bass)
2. First Inversion: Double the root if possible. If can't, double the fifth. If you can't, double the third.
3. Second Inversion: Double the fifth (the bass)

Stay tuned for the special doubling rule for this chord.

The Submediant as a Predominant Harmony

As I mentioned previously, this chord has predominant function. It is weaker than both IV and ii.

So now the order from weakest to strongest:

vi -> IV -> ii

This is typically the order you will see them in, too. It is not common to see them move from stronger to weaker within a chord progression, at least not in the classical era. In modern popular music, this relationship changes entirely.

However... there is more to this chord than its predominant function.

The Deceptive Cadence

The deceptive cadence happens when V (or V7) resolves to the submediant instead of tonic. This is often used as a surprise, thus the term "deceptive."

Often, they will lead to a full cadence shortly afterwards.

This cadence is possible because vi is acting as a Tonic Substitute. This means that it is taking the place of a tonic triad and fulfilling its role. Why is this possible? Tonic and submediant share two notes, the two notes that best define the tonic triad: Do and Mi

Therefore this chord is also a (weaker) tonic function.

How can you tell when its acting as which? It isn't hard to determine. 99% of the time this chord only has tonic function when it follows a dominant harmony. Otherwise it has predominant function.

Notice in the examples above what note is doubled in the submediant harmony. Here is the rule

When a submediant (vi or VI) follows a V chord, you must double the third of the submediant chord

Why? We double for function. If it is functioning as a tonic chord, treat it like one. Double Do.