Voice-Leading in Root Motion by Fifth/Fourth in Inversions Inverting triads adds a new wrinkle to the voice-leading of chords related by fifth. Since the root is no longer in the bottom, parallel fifths are less likely. However, parallel octaves become somewhat more likely. We end up having more options, but we pay for these options by having less guidance on the use of these options.
Complete Triads in the Upper Voices In root position triads, we saw that although we are allowed to double the fifth instead of the root, it is better to double the root. The reason is that all else being equal, voice leading works best when the three upper voices contain a complete chord, regardless of what is in the bass. This is still true for second-inversion triads (which would then carry the doubled fifth), and in this case, the common-tone method is almost always used. Write a complete triad in the upper voices, and resolve by common tone:
Note that second-inversion triads normally resolve obliquely in both the bass and its octave – it is not considered parallel octaves when the voices do not move.
First-Inversion Triads In first-inversion triads, however, all else is not equal. Since the third is in the bass, and thirds tend to be active tones (wanting to move by step, and often in a specific direction), having another copy of the third in the upper voices tends to cause parallel octaves (in addition to the fact that doubled thirds are generally avoided anyway). So, instead, we must double either the root or fifth in the upper voices. Advice on doubling with first-inversion triads is limited and inconsistent. The following rules should be kept in mind: 1. Parallel octaves are caused by keeping the doubled pitches in the same two voices two chords in a row. 2. Parallel fifths are caused by placing the fifth in the same voice two chords in a row, above the root. 3. When the spacing between voices is correct in the first chord, spacing issues (including voice crossing and overlap) are caused by unnecessary skips.
Swapping the bass and an upper-voice Some teachers still prefer doubling the root over doubling the fifth. If we try to follow this advice for both chords, regardless of which one (or both!) is the inversion, then we see the bass line behaving like an upper voice and one of the upper voices moving like a bass line. This is okay, but we must be cautious about spacing in the second chord. Complete the following progressions by treating one inner voice as a bass line:
However, this is one circumstance under which the use of a doubled fifth makes good sense – specifically, alternate between a doubled root and a doubled fifth. Remember that a doubled-fifth must be departed in the same way in which it is formed, with the fifths progression in contrary motion to root and third – be careful of spacing! Complete the following progressions by alternately doubling roots and fifths:
Other Types of Doubling Other teachers recommend always doubling the pitch that is in the soprano of the inverted chord (note that you obviously cannot do this if both chords are the same voicing, because this would create parallel octaves). If the root or fifth is in the soprano, this very often amounts to the same thing as alternately doubling roots and fifths. Later, when you practice inversions progressing by seconds, alternating doublings will become important, so it is worth getting used to it now. In this case, the doubled fifth should normally be on the inverted chord, not the chord that leads to it, since the doubled fifth originates from the root and third, and the third of a first-inversion chord will normally progress by step to a root or third, not a fifth.
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Another common recommendation is to double scale degrees , , and , irrespective of which chord tone they are (except, of course, when they are the third of the inverted chord). Regardless, the procedures are essentially as above: either move the root in the upper voices as though it were a bass line, or double the fifth and resolve the double fifths to root and third.
Chord Motion by First Inversion and Special Progressions As stated above, a first-inversion triad contains the third in the bass, which is an active tone – it wants to move by step. First-inversion triads may be approached by leap, but they will almost invariably be resolved by step in the bass. There are a few important excepts. First, any chord can freely be switched to any other position or voicing of the same chord. Hence, you can always move from a first-inversion triad to its root position.
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More significantly, is a special case amongst first-inversion triads. It is common to skip from its third in the bass to either the root of the chord or the third of the chord – that is, essentially, the chord may move freely to any position of the dominant chord.
V
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I^ V
In the skip from to , the bass performs the usual motion of the Similar Motion method. In the skip from to , the bass performs the usual motion of a Tertian Leap (this also occasionally happens in the essentially identical skip from to , which is one of the ways of filling the downwards leap between and ). Neither chord should have a doubled third. Hence, the same principle applies: treat two of the upper voices like the remaining voices of the respective methods, and move the remaining voice either like a bass or double the fifth.
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Complete the following special progressions:
On rare occasions, the bass may leap downward by fifth (upward by fourth), in imitation of root motion by fifth. This is not a common procedure, because true root motion by fourth is almost always better – in other words, when the bass line moves by fifth, the two chords ought to be root position chords. There is one exception, however: one chord in each key is diminished, which cannot be in root position (and is dissonant), and so a first-inversion chord that shares the same bass note might be preferable. In major, this means – instead of – ; it is less common in minor, because it would mean – instead of – (generally, – or the related – are better choices in minor, but in major, almost always progresses to , so is a better way to get to ).
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V^ iii iiO V
viiO iii iiO^ V I V^
N^ V
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