MUS 112 Study Guide P (Chapter 16)

The v and VII Triads; The Phrygian Cadence

Return to Home Page

Return to MUS 112 Menu

  1. The v and VII triads, along with the seldom-used vio and III+, the last of the diatonic triads, occur only in minor.  The Phrygian cadence also finds more use in minor than in major.

  1. The Minor Dominant Triad (v):  Since you are familiar with the behavior of the 6th and 7th scale degrees in (melodic) minor, you now may be able to imagine why the minor dominant chord may appear, even though it is rare.  It would appear in a situation where the descending melodic line (using the lowered 7th and 6th scale degrees) happens to place the lowered 7th in conjunction with a dominant chord harmonization.  For example, in C minor, the descending scale would be:  C Bb Ab G, etc. If the Bb were to be harmonized using the dominant chord, that chord would be G minor.

  1. The Subtonic Triad (VII):   in minor keys, built on the subtonic (b7); it does not function as does viio, built on the leading tone.  Usually the root of VII moves down a perfect fifth to III. Notice that this transposed "V-I" relationship causes the second chord, III, to sound like a tonic.  (When a chord progression other than V-I or V-i suggests that the second triad could be tonic, even if only briefly, the first triad is called a secondary dominant.  This process is called tonicization.  We will study secondary dominants in greater detail later.)

    So, VII-III and III-VI present dual auditory impressions:  (1) a simple diatonic progression in a key, and, (2) a tonicizing of the second triad.

    The subtonic triad (VII) appears most often in a harmonic sequence, or in a change of key, called modulation ... again, to be studied later.

  1. The Progression iv-VII:  In a minor key, the root of iv is a perfect fifth above the root of VII.  Thus, iv is useful both in a iv-VII progression and in the common iv-V and IV-viio progressions.  Most commonly, iv-VII is used in the harmonic sequence known as the circle progression.
  1. The Triads vio and III+:  The use of vio is very limited.  It harmonizes the #6 scale degree in minor.  As a diminished triad, it usually appears in first inversion to eliminate the tritone interval.  The III+ is an augmented triad, of course.  It appears due to the raised leading tone (#7, which is the fifth of the triad) of the minor key.
  1. The Medieval Modes (Appendix D):  The modes were used extensively from medieval times to the seventeenth century, and have seen a resurgence in popularity during the Impressionist era and 20th Century.  These are like the major and minor scales in that all consist of seven scale steps.  But each mode begins on a different letter name and uses only the "white notes" of the keyboard.  Therefore, the location of half and whole steps differ in each mode, creating a different "flavor" for each.

The first scale step in any mode is known as its final, rather than "tonic."  (The concept of tonality had not yet been developed when modes first came into use.)

When the range of the melody is generally between the final and its octave, the mode is said to be authentic.

When the range of the melody is generally between the fifth of the scale and its octave, the mode is said to be plagal.  The prefix "hypo-" becomes part of the name of the plagal modes, e.g., hypodorian, hypophrygian, etc.

Our modern "major" scale corresponds to the Ionian mode, and our "natural minor" scale corresponds to the aeolian mode.

A mode on B, called Locrian, is theoretical.  Because it has a tritone from its tonic to its dominant (B-F), it was not considered useful.

Following is a list of the medieval modes:

Dorian:  like natural minor but with a raised 6th scale step.
Phrygian:  like natural minor but with a lowered 2nd scale step.
Lydian:  like major but with a raised 4th scale step.
Mixolydian:  like major but with a lowered 7th scale step.
Aeolian:  same as natural minor.
Ionian:  same as major.

  1. As with the major and minor scales, the modes may begin on any tone as long as the arrangements of half and whole steps remain the same.  Since the final of each transposed mode lies in the same relationship to the tonic of the major scale with the same key signature, the identity of a transposed mode can be quickly determined:

Dorian:  The final is always the second degree of a major scale.  E.g., a mode which shares the key signature with F major but whose final is a G (2nd scale degree in F) would be a dorian mode transposed to G, referred to as G Dorian.

Phrygian:  The final is always the third degree of a major scale.  E.g., a mode which shares the key signature with D major but whose final is an F# (3rd scale degree in D) would be a phrygian mode transposed to F#, referred to as F# Phrygian.

Lydian:  The final is always the fourth degree of a major scale.  E.g., a mode which shares the key signature with A major but whose final is a D (4th scale degree in A) would be a lydian mode transposed to D, referred to as D Lydian.

Mixolydian:  The final is always the fifth degree of a major scale.  E.g., a mode which shares the key signature with Bb major but whose final is an F (5th scale degree in Bb) would be a mixolydian mode transposed to F, referred to as F Mixolydian.

Aeolian:  The final is always the sixth degree of a major scale.  E.g., a mode which shares the key signature with Ab major but whose final is an F (6th scale degree in Ab) would be an aeolian mode transposed to F, referred to as F Aeolian.

Ionian:  The final is always the first degree of a major scale.  E.g., a mode which shares the key signature with G major would have the same final (1st scale degree in G) as the tonic, therefore, it would be an ionian mode transposed to G, or G Ionian (same as G major).

  1. Determining a Transposed Mode:  This is the above procedure in reverse.  Examples:

The final is an A and the key signature has one sharp:  The major key would be G.  Since A is the second scale degree in G major, the transposed mode would be ... dorian.

The final is a G and the key signature has three flats.  The major key would be Eb.  Since G is the third scale degree in Eb major, the transposed mode would be ... phrygian.

The final is a G and the key signature has two sharps.  The major key would be D.  Since G is the fourth scale degree in D major, the transposed mode would be ... lydian.

The final is F# and the key signature has five sharps.  The major key would be B.  Since F# is the fifth scale degree in B major, the transposed mode would be ... mixolydian.

The final is Eb and the key signature has six flats.  The major key would be Gb.  Since Eb is the sixth scale degree in Gb major, the transposed mode would be ... aeolian.

The final is E and the key signature has four sharps.  The major key would be E.  Since E is the first scale degree in E major, the transposed mode would be ... ionian.

Note:  On occasion, composers will use "incomplete" key signatures.  That is, the key signature may have only two sharps, but the accidental G# will appear throughout the composition.  In such cases, one should consider that the equivalent major key signature has "three" sharps rather than two in determining the transposed mode.  (Pretty sneaky, eh??)

  1. Half Cadences; the Phrygian Cadence:  Any diatonic triad except viio and VII can precede the V triad to create a half cadence at an appropriate cadential point.  Common are ii-V and IV-V, in both major and minor.  One of these, iv6-V (in minor), carries a special designation, the Phrygian cadence.  In this cadence, the soprano descends by whole step while the bass descends by half step–a characteristic of the phrygian mode (b2-1).  Even if the voices are reversed and the half step occurs in the soprano, the cadence would still be considered phrygian.

The phrygian cadence also exists, though rare, in a major key as ii6-III.  The III triad in a major key is usually considered a secondary dominant chord (to be studied later).  But as a member of the phrygian cadence it usually returns directly to tonic.

  1. Writing the v and VII Triads in a Minor Key:  No new part-writing procedures are required for either of these triads.  Each triad contains a lowered 7th scale step.

In the dominant minor (v), this tone must descend.

In the VII triad, the lowered 7th scale degree assumes the role of the root of a secondary dominant chord; therefore, its properties are the same as those of the root of the dominant triad.

  1. Writing the Phrygian Cadence:  In the phrygian cadence, the iv6 triad can be written with any doubling.

Return to Home Page

Return to MUS 112 Menu