(musicTheory2) Lecture Notes: Leading Tone Seventh Chords

• 7ths are dissonant intervals. The chordal seventh must be PREPARED (approached by step or same tone, P – N – Sus; rarely as an appoggiatura), and RESOLVED (down by step). This applies no matter what the root is (or Roman numeral classification)

Fully diminished leading tone seventh chords are typically part of the minor mode. You have to raise the leading tone in minor. In major, the leading tone seventh is naturally half-diminished. It is often altered (lowering scale degree 6) to make it fully diminished.

vii°7 is comprised of all minor thirds. It is fully symmetrical (going up a minor third from the chordal seventh takes you to the root, up an octave). There are two interlocking diminished fifths (root – fifth; third – seventh).

Leading tone seventh chords are part of the Dominant class, and usually are embellishing harmonies (parentheses, unstemmed).

• Whatever the inversion, the bass usually moves in a linear fashion, and the movement matches common non-chord tone classifications (Passing, Susp, Neighbor).
• The LT seventh chord substitutes for inversions of V7 with the same bass note, i.e.,
  • vii°7 for V6-5 (neighbor to tonic)
  • vii°6-5 for V4-3 (passing between root pos tonic and first inv tonic)
  • vii°4-3 for V4-2 (Susp resolving down to I6; appogg to I6)
  • vii°4-2 is rarely used

Resolution:

• To avoid trouble, resolve the tritones properly (diminished fifths in, augmented fourths out). This typically leaves you with a doubled third on the following tonic.
• vii°6-5 moving to root pos i doesn’t resovle the tritones properly. (scale degree 2 should go to 3) In that case, make sure that the chordal seventh isn’t in the soprano. (unequal fifths stand out)