Consider this phrase from one of Bach's settings of the chorale O Ewigkeit, du Donnerwort
The bass-line consists of a straightforward tonic expansion followed by chord IV acting as intermediate harmony leading to V in an initial authentic cadence. A closer examination of the inner parts, however, reveals there is more going on than a simple IV-V-I cadential progression. Bach has enriched the harmony by adding a dissonance to chord IV turning it into chord IV7.
This new sonority does not change the basic function of chord IV as intermediate harmony, rather, the added dissonance intensifies that function. In the same way that V7 acts to intensify chord V, IV7 intensifies chord IV as it leads to chord V. The other two chords considered in this unit, II7 and II6/5, also have the same basic function - they act as an intensification of intermediate harmony. There are two fundamental ways of introducing the dissonant seventh of chord IV7, II7 and II6/5. The Bach example illustrates one of these methods.
Not only must the dissonant note be resolved (like the dissonance of chord V7) but because it is a less familiar sonority, it must also be prepared. This configuration of dissonance is exactly the same as a fourth species contrapuntal suspension. So, the first method of introducing the dissonant note of these new seventh chords is to prepare it in the previous chord and hold it over in a common part into the seventh chord itself and then resolve the dissonance down, by step as the progression moves to dominant harmony. (Chord V or a substitute). The second method of introducing the dissonant seventh involves a simple intermediate harmony expansion.
In each of these examples, the basic triad occurs first and the dissonant seventh is introduced as a passing note. Note that, just as in the previous method, the dissonance resolves down, by step when the progression moves to chord V. To summarise, chords II7, II6/5 and IV7 act as an intensification of intermediate harmony. As such, they MUST move to dominant harmony. The dissonant seventh of these chords should be treated carefully. Whenever these chords are used, the dissonance will always resolve down, by step (scale degree 3 - 2, in the case of chord IV7 and scale degree 1 - 7 in the case of chords II7 and II6/5). In addition to the dissonance being resolved, it must be introduced either by being prepared as a common note in the same part with the previous chord, or as a passing tone coming out of an intermediate harmony expansion.
1) Identify the errors in the following progressions.
2) Identify the method by which the dissonant seventh has been introduced in the following progressions.
Created 22nd September1999 Authorised: Faculty of Music Copyright 1999 University of Melbourne Maintenance: tmckenry@unimelb.edu.au