Voice Leading Seventh Chords in Inversion Inverted seventh chords must obey the same restrictions as inverted triads and as seventh chords. That is, like root position sevenths, the roots nearly always progress downwards by fifth, with the seventh resolving downward by step (and, ideally, with the third resolving upwards by step); and like inverted triads, they nearly always resolve by step in the bass (often in a specific direction, according to the rules just mentioned). In addition, unlike root position seventh chords, inverted seventh chords should only rarely be incomplete, which limits the available methods. On the other hand, since the bass is no longer moving from root to root, these seventh chords and the chords to which they lead can always be complete. Almost invariably, the remaining voices follow the basic pattern: thirds and fifths converge to the root, roots stay put to become the fifth, and sevenths resolve down to the third.
First Inversion For a first-inversion dominant seventh, the bass note is the leading tone, and must resolve upwards, without exception (since it is in an outer voice); for non-dominant sevenths, it is no longer a leading tone, but as the note one step below is not part of the subsequent chord, it likewise has nowhere to go but up. Hence, it nearly always leads to a root position triad. The rest of the voices follow the expected pattern.
Third Inversion Like first-inversion sevenths, the resolution of third-inversion seventh chords is fixed: the bass note is the chordal seventh, which always needs to resolve downwards; hence, the third-inversion seventh chord must, itself, resolve downwards – almost invariably to a first-inversion triad. The remaining voices resolve as stated above.
Second Inversion Second inversion is different from either first or third inversion. In a dominant seventh, the bass note is scale degree , and while it is still an active tone, and must resolve by step, it can resolve equally well in either direction; thus, the second-inversion seventh chord may resolve either up to a first-inversion triad or down to a root position triad. When it resolves downwards, the voice leading follows the guidelines given above.
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When the bassline resolves upwards, there is a slight difference. The upper voices do, indeed, move as expected. However, the bass voice must move to the third, just as the chordal seventh must also move to the third. This means that the resulting chord will have a doubled third. This is one of the only times when the third should be doubled.
Third-Progressions, Parallel Tenths, and Exceptions There is one exception to the usual rule that the seventh of a seventh chord must resolve downwards. The alternation – – , especially at the beginning of a phrase, strongly recommends the thirdprogression – – . If this melodic line is instead placed in the bass line, the chord progression becomes – – . This third-progression can then be harmonised in parallel tenths by another thirdprogression, – – , in the soprano. This means that the seventh, which is scale degree , does not resolve downwards, but under this circumstance, the excellent effect of the two third-progressions in parallel thirds overrules this usual requirement (and note that the third is not doubled in this case).
I V I 1 2 3 I V# I^ 3 4 5
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