PROLONGATIONS OF HARMONIES

A prolongation of harmony happens when two or more successive harmonies can be considered as the elaboration of the same harmony. We say that these harmonies prolong (sustain in time) the harmony which they elaborate. A prolongation enables us to look from a greater distance and identify larger harmonic units. 

The prolongation originates from the Schenkerian analysis which is based on the theories of Austrian music theorist and composer Heinrich Schenker. Since Schenkerian analysis is a complex subject on which many books have been written, it is out of the scope of this book. However, in this chapter, a few cases of the prolongation are presented and explained using harmony analyses. 

Often, a certain harmony changes to another one and then immediately returns back. This is most often used as the prolongation of the tonic or dominant harmony. The next figure shows the harmony analysis of the beginning of Mozart's Piano Sonata in C major K. 545. 

Figure: The beginning of Mozart's Piano Sonata in C major K. 545

We see the prolongation of the tonic harmony. It consists of a few changes from the tonic harmony to another one, followed by the immediate return to the tonic one. These non-tonic harmonies elaborate the tonic one. That is, the tonic harmony is structurally important here, while the other harmonies are used to embellish it. This is the reason why these other harmonies are called embellishing chords. It is often said that they belong to the surface layer of music, while the prolongated harmony belongs to the depth layer. Sometimes, embellishing chords are annotated in the parenthesis and the prolongated harmony is annotated without the parenthesis.

An embellishing chord is either a passing chord or neighboring chord. An embellishing chord that leads from a certain position of a chord to a different position of the same chord is called a passing chord. An embellishing chord that leads from a certain position of a chord to the same position of the same chord is called a neighboring chord. This is somewhat similar to the passing and neighboring nonchord tones which were examined in chapter Types of nonchord tones. The harmonies that appear between the tonic harmonies in the above-mentioned prolongation are neighboring chords. 

The next figure shows how we can use more of nonchord tones in the harmony analysis to explain why first four measures of Mozart's Piano Sonata in C major K. 545 can be considered as the tonic harmony. The important requirement here is that we can justify all the nonchord tones as melodic embellishments that support voice leading. To do that, we must view the Alberti bass figures in the lower staff as a compound melody. A compound melody is a single melody which implies more than one part (voice). The Alberti bass figures in the lower staff imply three parts (voices). For instance, the Alberti bass figures in measure 1 suggest three simultaneously sounding notes: C4, E4 and G4. In the next figure, all the implied parts (voices) in the lower staff are explicitly shown and all the nonchord tones are annotated. We see that all the nonchord tones in the lower staff are neighboring tones. For instance, the nonchord tone D4 in measure 2 in the lower staff is the neighboring tone between the chord tone C4 in measure 1 and the chord tone C4 in measure 2. The nonchord tone F4 in measure 2 in the lower staff is the neighboring tone between the chord tone E4 in measure 1 and the chord tone E4 measure 2. 

Figure: The beginning of Mozart's Piano Sonata in C major K. 545 as the single tonic harmony

The next figure shows a similar situation where the tonic chord in the second inversion (the tonic six-four chord) is used to elaborate the dominant harmony. If we view C5 and E5 as chord tones then we find the tonic six-four chord followed by the dominant harmony. However, if we view C5 and E5 as nonchord tones (E5 is the passing tone between the chord tones F5 and D5 while C5 is the suspension resolving to B4) then we find only the dominant harmony. Such prolongations of the dominant harmony usually happen at cadences (a half cadence or an authentic cadence like in the figure) and are called the cadential six-four chord. Sometimes, a bracket is used to emphasize that the dominant harmony is prolonged.  

Figure: The cadential six-four chord

In this chapter, the same passages were viewed both using large scale and small scale harmonic units. It is important to understand that both views are correct. It really depends on what we want to emphasize in the particular harmony analysis.