Scale Degree Tendencies in the Dominant Harmony
It is important to think about the scale degrees present in any harmony. For the dominant triad you have scale degrees 5, 7, and 2. The leading tone (7) strongly wants to resolve to tonic (1). The supertonic (2) also wants to resolve to either tonic (1) or the mediant (3).
I – V – I, and Principles of Prolongation
Harmonies can group together to extend, or prolong, the function of a chord class. I – V – I happens a lot at the beginnings of phrases to prolong the opening tonic. In this way, the dominant harmony serves in an auxiliary way to the tonic harmony, embellishing it. We can think of this embellishment in terms that draw on our past species counterpoint experience as we refer to the outer voice movement – in this case, the soprano movement. In tonic prolongations we can refer to the soprano movement as consisting of specific non-chord tone (NCT) movements. (In minor, scale degree 7 is always raised to form the leading tone.)
- Lower Neighbor Note Progression (LN): Soprano moves 1 – 7 – 1.
- Passing Tone Progression (PT): 3 – 2 – 1.
- Upper Neighbor Note Progression (UN): 1 – 2 – 1.
- Incomplete Neighbor Progression (IN): 3 – 7 – 1.
Voice Leading Issues
The lower neighbor and incomplete neighbor progressions move according to the principles we have been studying. The roots area fifth apart, so there will be one common tone between chords. Keep the common tone in the same voice throughout the three-chord progression, and move the other voices as smoothly as possible to the nearest chord tones. All chords will have doubled roots, and will be complete triads.
Both the passing tone and upper neighbor progressions have slight issues to deal with. To move from V to I with complete triads, scale degree 2 in the dominant needs to move to scale degree 3 in the tonic resolution. Since both progressions have soprano lines that move 2 to 1, you can not use our standard voice leading techniques. In both of these cases, resolving the leading tone leads to a tripled root. This is ok. If the common tone remains in the same voice from V – I, then you will not have a third in the tonic triad. This is not ok. Drop the upper-voice 5 in the dominant down to 3 in the tonic.
All of these examples are in the book on p. 161.
Frustrating the Leading Tone
It is possible in some cases to not resolve the leading tone to tonic, resulting in a frustrated leading tone. The book, like most, is wishy on this. For now, I’d like to maintain some rigor and offer only one possibility for this. The leading tone can be frustrated if an adjacent upper voice (the voice above it) moves to the tonic resolution at pitch (not in another octave). On p. 161, see example 2.2F. Example 2.2E shows a frustrated leading tone without same pitch resolution. AVOID THIS FOR NOW.
If the leading tone is frustrated, it drops down a major third to scale degree 5 in the tonic harmony. It can not go anywhere else!
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