[Smt-talk] II6/4

[Olli Väisälä]

Dear List,

Relating to the elusive and inexhaustible subject of consonant/ 
dissonant 6/4s, I would like to draw attention to a family of  
consonant II6/4s that may not have received much attention in the  
literature.

It is well known that in three-voice counterpoint 6/4s sometimes  
function as "temporary consonances" in a series of 6/5–6/4  
suspensions. A simple example is given by Bach's Fugue in C major  
from WTC II, mm. 40–41. In terms of basses and FB numbers, the  
progression is:

E 6/5 6/4, D 6/5 6/4, C 6/5 6/4#

Since the progression heads locally towards G-major, it can be  
retrospectively perceived as a prolongation of II, which spans from  
the first 6/4 to the last 6/5; hence II6/4–6/5. The functional bass  
(C) is that of the 6/5. The second 6/4 is a passing chord and the  
last 6/4# (VII6/4) stands for V4/2.

This progression and its variants and elaborations are not uncommon  
in Bach. Some additional examples:

– Fugue in C# Major from WTC I, mm. 25–26. Here the first suspension  
is 7/5–6/4, and the II6/5 is replaced by a direct motion towards the  
VII6/4.
– Sinfonia (Three-Voice Invention) in C Minor, mm. 23–25. Here we  
have three 7/5 suspensions: Ab 7/5 6/4, G 7/5 6/4, F 7/5 6.
– Fugue in G Major from WTC II, mm. 35–37.
– (A somewhat related usage without any chain of suspensions is when  
a 6/5 suspension is about to resolve to II6/4, but the bass simply  
falls a third at the moment of resolution to enable a II6/3. For  
example of this, see the Neapolitan in Fugue in Ab Major from WTC,  
fourth bar from end.)

Apart from surface occurrences of this voice leading model, I have  
occasionally also found it useful to apply it to Schenkerian  
interpretation, even when there is no explicit II6/4 present. (Even  
in some of the above examples bass figuration prevents a literal 6/4  
simultaneity.)

A case I am pondering right now occurs in Mozart's "Ah, vous dirai- 
je, Maman" (= "Twinkle, twinkle, little star") Variations. In  
variations II, III, and IV, there the following progressions occurs  
in mm. 5–7:

In terms of FB: A 6/5 B 6/5, C 9 A, F 6/5

In terms of "chordal analysis": IV6/5 V6/5, I9(-8) VI, II6/5.

Now in each of these variations the span from the "IV6/5" to the  
II6/5 is bound together by unified design, which especially in  
variations III and IV clearly contrasts with mm. 1–4. Since the  
"IV6/5" and II6/5 are also hypermetrically stronger than the  
intervening "I", I strongly tend to perceive the span framed by the  
"IV6/5" (m. 5) and II6/5 (m. 7) as pre-dominant prolongation and the  
"I" (m. 6) as an apparent tonic. The best way I can see for  
interpreting the "IV6/5" is as a suspension to II6/4, which then  
fails to materialize as the bass moves. As in the Bach examples, a  
chain of supsensions connects the "IV6/5" to the II6/5, but instead  
of a stepwise bass line (^6^5^4) we have a detour through the  
apparent tonic (^6^7^1^6^4).

I would be happy to get any comments on (1) this and related uses of  
II6/4 in general and (2) further relevant Mozart examples in  
particular. The above progression starting from "IV6/5" sounds  
readily idiomatic, but, since I am by no means a Mozart expert, no  
comparable examples pop into my mind right now.

Olli Väisälä
Sibelius Academy
University of the Arts, Helsinki
ovaisala at siba.fi