Identifying Secondary vii Diminished Triads (viio)
Many of the concepts discussed in the previous chapter apply here, since the leading tone diminished chord also serves a dominant function in tonal music. The leading tone diminished triad (viio) contains the same upper three pitches as a dominant 7th (V7) chord in the same key. While the 3rd of the secondary dominant is raised, the same note raised by an accidental is the root of the viiotriad. Rather than moving down a P5 to the tonicized pitch, the note a half-step up from the altered root of the viio is tonicized.
The viio triad contains the 7th, 2nd, and 4thscale degrees in a key, but it is often found in first inversion. This facilitates contrary motion in resolution. The 2ndscale degree of the key of the tonicized chord is found in the bass in first inversion, and is typically doubled in four voices.
Secondary vii Diminished Seventh Chords (viio7)
The secondary viio triad is built on a raised scale degree, which has an accidental. The viio7 chord is built on the same altered scale degree. It may be either half-diminished or fully diminished with a chromatically lowered 7th above the root in major keys. The most frequently used secondary viio7 chords are of the fully diminished variety. This chord is actually borrowed from the parallel minor key into the major key. Borrowed chords will be discussed in the next lesson.
Spelling Secondary vii Diminished Seventh Chords (viio7)
This chord may be spelled four different ways, depending on the key or tonicized pitch to which it belongs. In general, the raised note is always the root and the lowered note is the seventh. This is a clue to the harmonic goal of the viio7 chord. For example, in the key of C major the viio7/vi is spelled G#-B-D-F. The F-natural (7th of the chord) is lowered from F# in the key of A, which is vi in C. Note that the viio7 chord must be spelled as a stack of minor thirds, which makes it completely symmetrical, and it can only be transposed three times. This chord, as well as the secondary V7, is frequently used as a pivot chord moving to an unrelated key in a chromaticmodulation. In this case, it may be spelled correctly in the new key, and “incorrectly” in the original key. This enharmonic spelling will be discussed further in the lesson on Modulation. In the musical example below the same viio7 chord resolves to four different minor keys, and is spelled differently in each key.
Voice-Leading Secondary vii Diminished Triads (viio)
Resolve each note according to its chromatic inflection, or tendency. Raised pitches continue upwards, as a general rule, and lowered pitches move down. The raised root of the secondary viio7 chord resolves up by half-step to the tonicized pitch. The diminished 7th of the viio7 chord typically resolves down by half-step. In first inversion, these two voices move in contrary motion smoothly to the doubled root of the tonicized chord. The other two voices may move downward stepwise, or into an inverted chord of resolution with the 3rd or 5th doubled.
Diminished 7th Chord Enharmonically Spelled and Resolved