At this point, we've discussed the two most common diatonic 7th chords: V7 and II7.
Now, we will discuss "The Others". These are the VII7, IV7, VI7, I7 and III7 chords.
We will take a little time with each of these, give them a listen, discuss the way they sound and briefly discuss their functionality. Just because these are a little less common, that's no reason to not bring them up because they are often featured in great music!
KEY WORDS
DIATONIC- When a triad, chord or melody consists of notes solely from the given
key, it is considered to be DIATONIC.
TONIC ( I )- A note in a melody or a chord in a progression based on scale degree 1 of the given key. This is considered "home base", the origin and destination of a piece of music.
SUPERTONIC ( ii ) - A note in a melody or a chord in a progression based on scale
degree 2 of the given key.
MEDIANT ( iii )- A note in a melody or a chord in a progression based on scale
degree 3 of the given key.
SUBDOMINANT ( IV )- A note in a melody or a chord in a progression based on scale degree 4 of the given key.
DOMINANT ( V )- A note in a melody or a chord in a progression based on scale degree 5 of the given key.
SUBMEDIANT ( vi )- A note in a melody or a chord in a progression based on scale
degree 6 of the given key.
SUBTONIC ( viiº7 )- A note in a melody or a chord in a progression based on scale degree 7 of the given key. In the major key, it can be often referred to as the LEADING TONE because it wants to resolve up to the TONIC.
*It should be noted that all the above Roman numeral examples given were shown as uppercase (major) or lowercase (minor) as they relate to the MAJOR scale. Below are the chord qualities for major vs. minor:
MAJOR SCALE:
I - ii - iii - IV - V - vi - viiº - I
MINOR SCALE:
i - iiº - III - iv - v - VI - VII - i
VOICE LEADING CONSIDERATIONS
The voice leading considerations for the 7th chords are the same as they are for their complimentary DIATONIC TRIADS.
-The 7th of the chord must resolve down a step.
-Because there are 4 chord members to the 7th chord, there is rarely a need for doubling in 4 part textures.
If you decide to double a chord member, don't make it the LEADING TONE of the scale.
Otherwise, you may be subject to parallel octaves.
-If you decide to omit a chord member, the 5th is your best bet. The ROOT gives you the chord name and function.
The 3rd gives the chord it's quality (major or minor). And, of coarse, without the 7th, it would cease to be a 7th chord.
-The same rules apply to the inversions of these chords.
-In jazz and pop music, these rules aren't as widely observed. In the7th chords aren't
considered as dissonant as they are in classical music.
EXAMPLES
*As you listen to this episode, you will hear us reference SCALE DEGREES
(1, 2, 3, 4, 5, etc...) and CHORD MEMBERS (root, 3rd, 5th, 7th, etc...).
Be sure to not confuse them!
THE VII7 CHORD
The VII7 chord takes on different qualities in different keys.
In MAJOR keys (we'll use C major) the VII7 chord is a HALF DIMINISHED SEVENTH chord.
MAJOR KEYS
In MAJOR keys (we'll use C major) the viiø7 chord is a HALF DIMINISHED SEVENTH chord.
Below, we have a viiø7 in 1st inversion (6/5). It is a B HALF DIMINISHED (ø) 7 chord.
Because it is in 1st inversion, we have the 3rd (D) in the bass. The ROOT (B) lies in the tenor voice,
the 5th (F) in the alto and the 7th (A) in the soprano.
There are no accidentals or foreign notes, so this chord is DIATONIC.
NATURAL MINOR
In NATURAL MINOR (we'll use C minor) the VII7 chord is a MAJOR MINOR 7 chord.
Below, we have a VIl7 in root position (7). It is a Bh MAJOR MINOR 7 chord.
Because it is in root position, we have the ROOT (Bb) in the bass.
The 3rd (D) lies in the tenor voice, the 5th (F) in the alto and the 7th (A) in the soprano.
There are no accidentals or foreign notes, so this chord is DIATONIC.
On occasion, in MINOR keys, the seventh scale degree will be sharpened.
This is done when using the HARMONIC MINOR scale.
This will result in a FULLY DIMINISHED SEVEN CHORD (º).
HARMONIC MINOR
In HARMONIC MINOR the viiº7 chord is a FULLY DIMINISHED 7 chord.
The only difference between the VIl7 chord above and the Bº7 below is that the Bb has been raised to a B♮ (see the accidental below). Because of this accidental, the resulting B°7 chord is not considered to be DIATONIC to the C MINOR scale.
THE IV7 CHORD
Like the IV triad, the IV7 chord takes on different qualities in different keys.
MAJOR KEYS
In MAJOR keys the IV7 chord is a MAJOR SEVENTH chord.
MINOR KEYS
In MINOR keys the iv7 chord is a MINOR SEVENTH chord.
The SUBDOMINANT (IV) chord, like the triad, wants to go to V or viiº.
It will sometimes pass through a II first.
THE VI7 CHORD
MAJOR KEYS
In MAJOR keys the vi7 chord is a MINOR 7 chord.
MINOR KEYS
In MINOR keys the VI7 chord is a MAJOR 7 chord.
The SUBMEDIANT 7th chord (VI7), like the triad, wants to go to a PREDOMINANT chord,
such as II or IV.
INVERSIONS can come in handy because moving from ROOT POSITION VI to ROOT POSITION V,
parallel octaves can occur.
THE I7 CHORD
MAJOR KEYS
In MAJOR keys the I7 chord is a MAJOR 7 chord.
MINOR KEYS
In MINOR keys the i7 chord is a MINOR 7 chord.
Like the I triad, the I7 chord can go virtually anywhere, but tends to go to IV, II or VI.
Adding that 7th to a I chord robs it of it’s stability a bit. The TONIC flavor is marred somewhat.
This is not a problem in jazz or pop music.
THE III7 CHORD
MAJOR KEYS
In MAJOR keys the iii7 chord is a MINOR 7 chord.
MINOR KEYS
In MINOR keys the III7 chord is a MAJOR 7 chord.
The MEDIANT wants to go to a PREDOMINANT or back to the TONIC.
Sometime it will act as a substitution for I. Or it may move to and from I, in succession.
It will often to go to VI, but will sometimes move to IV fairly smoothly.
THINGS TO REMEMBER
-The 7th chord QUALITY is inconsequential to the FUNCTION of the chord. These chords want to move in the same directions as do their DIATONIC TRIAD counterparts.
-The same voice leading rules apply to the 7th chords as do their TRIAD counterparts, in harmonic progression.
-The use of the HARMONIC MINOR scale in MINOR keys can alter the quality of the 7th chords. When using the NATURAL MINOR scale, for example, the VII7 chord is a MAJOR MINOR 7 chord (Mm7). When using the HARMONIC MINOR scale, the VII7 chord becomes a FULLY DIMINISHED 7 chord (˚7).
-The FULLY DIMINISHED 7th chord is said to be INTERVALLIC or SYMMETRICAL. This chord consists of four MINOR 3rd intervals and land on the ROOT. 12 notes are divided, equally and symmetrically, into 4.