If we think back on our progression through the course thus far, we began by studying individual pitches, then combined those pitches into intervals, and then assembled those intervals sequentially and simultaneously to create melodies and chords respectively. Next, we studied a simplified version of counterpoint in order to examine how the combined vertical and horizontal aspects of music interact to create basic tonality. While counterpoint provides a framework for understanding harmony, it is primarily a study of how the horizontal aspect of music, melody, combines and implies harmony; it does not establish the vertical aspect of music, harmony, as a standalone concept.
Therefore, we can use a simple counterpoint exercise to begin determining how harmony functions, because harmony is defined by the melodic tendencies of certain pitches within a diatonic scale.
Each measure of the next example implies the same two harmonies repeatedly–one on the first half note and the second on the second half note.
All of the two-voice progressions in the example imply harmonies of V moving to I in the key of C major, although you could make the argument that some of the implied harmonies are actually viio instead of V7. The bass movement of the first three measures highlights V moving to I, but even once the bass movement changes, you should still hear the same progression of tension and release.
From this, we may conclude that two voices–in this case a soprano line and a bass line–are enough to imply tonality. Furthermore, we can observe that the pitches within a V7 chord pull toward resolving to the pitches of the I chord. One chord is stable and final, while the other wants to resolve to the stable and final chord.
This is harmonic function. A chord’s function is a way of describing how it works within the context of tonal music.
In diatonic music, there are three basic categories of harmonic function: tonic, dominant, and pre-dominant.
You may be tempted to make some definitive conclusions about voice-leading from looking at these examples–such as ti resolving to do, or fa resolving to mi–but be careful not to over-generalize with these ideas. If you make the assumption that ti always resolves to do without considering the context, you will make errors in situations where ti is not part of a dominant function. We will explore the true nature of tendency tones and their resolution in the next unit.
You may also notice that the chordal fifth is the least common chordal member in these examples, and as we will see when we begin voicing four-part harmony, the chordal fifth is indeed expendable. The root and third are best at implying a harmony, and the chordal seventh adds a strong resolution, whereas the fifth only provides a “fullness” to the chord. But not all chordal fifths are easily expendable, and sometimes composers will choose to imply/omit a chordal third (or even root!) given a particularly context. We will explore all of these ideas further in our part-writing studies.
Because of the importance of the V-I progression, we will introduce an important term in understanding harmony: the cadence. We will explore cadences further in the Unit 8, but for now, you may think of a cadence as a harmonic progression used to conclude a musical phrase. There are many types of cadences, but all of the progressions above are authentic cadences–cadences that have a V chord moving to a I chord. Bass movement is a key factor in determining the strength of a cadence. For example, measures 1 and 3 in the examples likely sound stronger to you than the last measure. The last measure not only lacks sol to do in the bass, it also does not have a tonic in the final chord. We will return to this idea when discussing cadences in detail in Unit 8a.