EPISODE 99
THE FULLY DIMINISHED 7TH CHORD

HOST- Jeremy Burns, Matthew Scott Phillips

GENRE- Theory

DURATION- 88:37

BUMPER MUSIC- "Diminish Me" (Area 47 Music)

ANNOUNCER- Mike Cunliffe

LISTEN

DESCRIPTION

We've almost said everything we can about the fully diminished 7th chord. ALMOST! In this episode we will explore this versatile chord and its many possibilities. We will hear it's use as a secondary leading tone chord (viiº7 of), as a modulatory technique, as a chain of viiº7 chords and as a counterpuntal element. Enjoy our chatter on this extraordinary chord!

KEYWORDS

DIATONIC- When a triad, chord or melody consists of notes solely from the given key, it is considered to be DIATONIC.

TONIC (1)- A note in a melody or a chord in a progression based on scale degree 1 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.

LEADING TONE (vii°)- A note in a melody or a chord in a progression based on scale degree 7 of the major key or #7 of a minor key.

SEVENTH (7)- This would be the 4th chord tone added to a TRIAD. It will be a 7th above the root of the given chord. It can be major, minor, augmented or diminished.

SECONDARY LEADING TONE (viiº/ )- This chord can act as a leading tone function to a chord other than the tonic.

MODULATION- Change of key.

EXAMPLES

AS A SECONDARY VI7 CHORD


-See the chord in measure 1. This chord is a FULLY DIMINISHED 7TH CHORD. Let's check out some of the places it can go:

1. In measure 2, the first chord (F#°7 in root position) would be considered the SECONDARY SEVENTH chord of G major. In the key of C, G major is the V. So this is considered the vii°7/V. Notice how the F# note moves up to the G of the following chord, in LEADING TONE fashion (up by a 1/2 step).

2. In measure 3, we begin with the EXACT same chord as in measure 2. But rather than F#07 in root position, let's rename this chord as an A°7 chord in 3rd inversion. Notice how the A note moves up to the Bb of the following chord, in LEADING TONE fashion (up by a 1/2 step). This would now be considered the SECONDARY SEVENTH chord of Bh major chord that follows. In the key of C, Bb major is considered NON DIATONIC. It does not "belong" to C major. We are now seeing some of the "portals" that have opened up when it comes to TONICIZING exotic chords.

3. In measure 4, we begin AGAIN with same chord as in measure 2. But rather than F#°7 in root position, let's rename this chord as C°7 chord in 2nd inversion. Notice how the C note moves up to the C# of the following chord, in LEADING TONE fashion (up by a 1/2 step). On the notation, it appears to be a lateral movement. But the C is still moving up a 1/2 step to C# This would now be considered the SECONDARY SEVENTH chord of C# minor chord that follows. Again, we have moved to a completely foreign chord!

4. In measure 5, we will rename the first chord as Eb°7 in 1st inversion. Notice how the Eb note moves up to the E of the following chord. Again, it appears to be a lateral movement. But the Eb is still moving up a 1/2 step to E. This would now be considered the SECONDARY SEVENTH chord of E minor chord that follows. In the key of C, E minor is considered the i chord. So this chord isn't foreign at all. It is DIATONIC to C major. So we can effectively label this chord as vi°7/it in the key of C major.

5. In measure 6, we will continue to honor the first chord as b°7 in 1st inversion. Notice how the Eb note moves up to the E of the following chord, just as in the previous measure. However, this E note is the root to the E major chord, rather than E minor in measure 5. E major is far removed from the key of C major. So, again, we made a huge leap in a short amount of time.


THE FUNCTION OF THIS CHORD IS FOGGY UNTIL YOU LISTEN TO WHERE IT GOES


AS A COMMON CHORD OF A MODULATION


-In this case, the FULLY DIMINISHED 7th CHORD (F#º7) functions as it did in the previous example. But rather than simply TONICIZING a new chord, it acts a SECONDARY LEADING TONE (viiº7 of) to a chord of a new key (I of G major). Thereby, it acts as a tool of MODULATION (a change of key). We solidify this by tacking on a V - I resolution, in the new key, in measures 5 and 6.


AS A COMMON TONE FULLY DIMINISHED 7 CHORD


-In this case, the FULLY DIMINISHED 7th chord acts as a means to prolong the tonic. It maintains the function of the tonic but colors up the texture as it moves away from and back to the tonic.


AS A CONTRAPUNTAL ELEMENT


-The chord in measure 3 is a diminished chord built on scale degree 5 (A) that resolves to scale degree 6 (Bb). This chord is acting as the vi° of VI (vi°/VI) in the key of Dm.


AS A CHAIN OF FULLY DIMINISHED CHORDS


-In this case, we want to move from I (C) to V (G) in the key of C major. Beginning with the second chord in measure 1 (C#º7), we move up chromatically by a 1/2 step for every note. This results in a CHAIN OF FULLY DIMINISHED 7tth CHORDS that flows all the way up to the V chord. That first chord in measure 4 (F#º7) could be considered as a SECONDARY FULLY DIMINISHED 7th chord of the V.