MUS 211 Study Guide B (Chapter 2)

Diminished Triads and Seventh Chords,
Including Secondary Leading Tone Functions

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  1. Just as the leading tone triad, viio, can progress to tonic in a dominant-to-tonic relationship, so can other major and minor triads be tonicized by their secondary leading tone triads.

  1. Secondary leading tone triads are normally written:  viio/V, for example.  An abbreviated symbol is also acceptable:  o/V, for example.  In that most diminished triads normally appear in first inversion, however, "o/V" is understood to imply "o6/."  Either analytical symbol is acceptable.

  • Note that all secondary leading tone triads except o/III include an accidental not in the key signature.  This exception is spelled the same as the diatonic iio (minor).  The distinction is determined by the resolution.

Uses of the Secondary Leading Tone Triads

  1. The simplest and most common use of the secondary leading tone triad is the o/triad followed by the tonicized triad.
  1. The o/V sometimes progresses to i-six-four (then V7-i) at the cadence.
  1. Sometimes the o/triad replaces a secondary dominant (I - V/V - V) at a (half) cadence:  I- o/V -V.
  1. The secondary leading tone triad is used effectively in the progression I-viio6-I6 (or the reverse), but on a pitch level other than tonic.

Diminished Seventh Chords

  1. There are two types of diminished seventh chords:
  • Fully-diminished seventh:  o7 (R, m3, d5, d7) (diatonic chord in minor)
  • Half-diminished seventh:  7 (R, m3, d5, m7) (diatonic chord in Major)
  • "Fully-diminished" chords are usually referred to as, simply, "diminished," whereas, "half- diminished" chords must be referred to as "half-diminished."
  1. There are only three diminished seventh "sonorities"--those built on any three consecutive half steps.  Any others will simply be an inversion of the three.
  • Different spellings of the same chord are analyzed by function.
  1. The seventh of the diminished seventh chord may resolve in either of two ways:
  • With a change of harmony at the point of the resolution of the seventh.  The seventh resolves downward by step.
  • With no movement in the other three voices, resulting in a major-minor seventh chord.  In such cases, the seventh can usually be considered a simple nonharmonic tone. (See p. 38.)

The Leading Tone Seventh Chord

  1. The leading tone seventh chord is a dominant-class chord because it has three tones in common with the dominant seventh chord of the key.
  1. There are three useful seventh chords built on the leading tone of a key:
  • viio7 in a minor key is a diatonic triad built on the leading tone, considering the raised 7th scale degree to be a diatonic tone.
  • viio7 in a major key is spelled identically to the viio7 in a minor key. To achieve this spelling in major, the sixth scale degree must be lowered one half step.
  • vii7 in a major key is a diatonic chord built on the leading tone.  It is used far less frequently than the diminished seventh chords.

The vii7 in minor is very rare since its seventh, which should descend, is also the raised 6th scale degree which should ascend.

  1. Like the dominant 7th chord, the viio7 and vii7 chords usually resolve to the tonic (I or i).
  1. The use of any diminished seventh chord in any inversion is acceptable, and, in fact, common.
  1. Resolution of the tritone factor (root/fifth) is generally as follows when the leading tone seventh chord resolves to the tonic chord (any voicing):
  • D5 resolves inward by a half step ("Din").
  • A4 resolves outward, or away, by a half step ("Away").
Half-diminished (7)   Fully-diminished (o7)
D5 ("Din"), A4 ("Away")   D5 ("Din"), A4 ("Away")
A     D       Ab    D    
FmE BkC   FmE BkC
D     A       D     Ab   
BkC FmE   BkC FmE
  1. Leading Tone Seventh Chord Partwriting Summary:
  • Resolve the seventh of the viio7 or vii7 (and inversions of each) down one diatonic scale degree.
  • Resolve the tritone (root/fifth) inward if a o5th, and outward if an +4th.  These recommended resolutions are not possible in every situation, however.

Secondary Leading Tone Seventh Chords

  1. The following are the most common secondary diminished leading-tone seventh chords:
  • Major:  o7/ii, o7/IV, 7/V, o7/V, o7/ vi.
  • Minor:  o7/iv, o7/V.

Again, "o7/ii" means "viio7/ii," and "o6/ii" means "viio6/ii."

Occasionally, a secondary diminished seventh chord will precede a chord other than a diatonic triad.

Regular Resolution of Secondary Leading Tone Seventh Chords

  1. The root (leading tone) rises a half step, while the seventh resolves down stepwise.
  1. When found in inversion, there is no change of spelling, and the actual root and seventh resolve exactly as does the root position.

Resolution of o7/V to Tonic Six-Four

  1. It has been established that the tonic six-four chord functions as a dominant chord containing two nonharmonic tones.  Therefore, the o7/V chord can just as easily resolve to a tonic six-four as to V.

Nondominant Use of Diminished Seventh Chords

  1. There are two other diminished seventh chords commonly used in music which do not function as secondary leading tone chords.  They are the #iio7 and #vio7 in major keys.
  • With each of these, the root of the chord resolves up a half step to the third of the following chord:  #iio7-I6 and #vio7-V6 or V six-five.

Other Considerations

  1. Diminished seventh chords are often used freely in succession without concern for resolution of sevenths or altered tones.

Descending Resolution of the Root of a Diminished Seventh Chord

  1. It is possible for the root (leading tone) of a diminished seventh chord to resolve downward by half step, using the same letter name.  For example:
  • In the key of F Major:  o7/V-ii six-five = B to Bb bass movement.
  • This movement does not occur in the nondominant chords #iio7 and #vio7.

The Melodic Augmented Second

  1. When using diminished chords, the melodic interval of an augmented second may sometimes appear.

Special Voice Leading for the viio6

  1. No established voice leading pattern, but:  double bass note, avoid skips of a tritone, and move all voices with as much stepwise movement as possible.

Tips regarding secondary leading-tone diminished-seventh chords in tricky keys

  1. The only secondary leading tone diminished triad / seventh chord that may have a flattened pitch as its root is Bb.  This chord progresses, or tonicizes, the Cb chord.  All others will be built upon a natural, sharped, or double-sharped pitch, depending upon the pitch class (and accidental) of the chord it tonicizes.
  1. The root factor of the secondary leading tone embellishing chord will have a different letter name (pitch class) than the chord it tonicizes.  For example:
Correct: Incorrect:
B#o7gC# Co7gC#
Fxo7gG# Go7gG#

 Handy-dandy explanation:  Think of the chord being tonicized as a temporary tonic.  In the first example above, in the key of C#, the leading tone would be B#, not C.  Likewise, in the key of G# minor, the leading tone would be Fx, not G.

  1. The principle above also applies when working with Roman numerals.  If, for example, in the key of B major you are asked to provide the chord o7/V, the correct chord spelling would be E#, G#, B, D, not F, Ab, Cb, Ebb, because E#, not F, is the leading tone in the temporary key of F# (major or harmonic minor).  Again, just remember that the secondary embellishing chord will be built on a different pitch class (letter name) than the chord it is tonicizing, which will be the equivalent of the letter name for the 7th scale degree in the temporary key.
  • Suddenly, you're in the key of Cb major and are asked to provide o7/V.  In this case, the correct spelling of the chord would be F, Ab, Cb, Ebb, because the leading tone in the temporary key of Gb is F.

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