SOUND PATTERNS

A Structural Examination of Tonality, Vocabulary, Texture,
Sonorities, and Time Organization in Western Art Music

by PHILLIP MAGNUSON

CHROMATIC PROCEDURES II

Chapter 34. Augmented 6th Chords

Chapter 32. Borrowed Chords
Chapter 33. Neapolitan Triad
.

34.1 EVOLUTION

So far, connections fall into three categories: diatonic chords, tonicizations, and borrowed chords. A progression with a diatonic connection looks like this.

The same progression with a tonicizing connection:

The same progression with a borrowed connection:

If both of the chromatic pitches from the previous two examples were to be employed at the same time, this is the result:

This hybrid connection ("X") is an AUGMENTED 6TH CHORD. Notice the interval between the two chromatic pitches (bass to tenor) is an A6, which gives this sonority its name.

34.2 CONTENT AND FUNCTION

The content of the basic augmented 6th chord is three scale degrees: raised ^4 (Fi) - lowered ^6 (Le) - ^1 (Do). This bears a resemblance to the subdominant triad, and is used as a connective (pre-dominant) harmony.

The traditional augmented 6th chord has the lowered ^6 (Le) in the bass voice (which allows for the interval of an A6 to be formed above it). This highly chromatic sonority, even though it can be stacked into 3rds, cannot be categorized as major, minor, diminished, or augmented; there is no Common Practice Period triad (or tetrad) that contains a d3 (the inversion of the A6). Consequently, there really is no root, and cannot be labeled with a Roman numeral.

34.3 NATIONALITIES

There are four variations of the basic augmented 6th chord described above, which are given "nationalities". There is no particular nationalistic connection to the names; they are simply convenient labels.

Notice that the last two are enharmonically the same (raised ^2 = lowered ^3), which is why they are both identified as Ger+6's.

34.4 VOICE LEADING

The essential voice leading for all nationalities of augmented 6ths:

It is the strength of these three half-step motions that gives an augmented 6th chord its powerful pull to dominant. It should be noted that each augmented sixth chord type is identical in both major and parallel minor keys, and that in minor keys, ^6 is already lowered (Le) and should not be altered.

34.5 EXTENSIONS

The customary use and context of the augmented 6th chord is set by tradition, but there are some "abnormalities" associated with them:

  1. Some composers find ways to take the Ger+6 directly to dominant, and still avoid the parallel 5ths.

    From measure 5 to 6, the tenor and bass are about to have parallel 5ths, but through a voice exchange between the tenor and alto, the problem is avoided.

  2. On occasion, augmented 6th chords may be used with a chord factor other than lowered ^6 in the bass.

    Mozart chooses to put the raised ^4 in the bass to add more contour to the bass line, since the previous measure was entirely lowered ^6.

  3. Augmented 6th chords can be used as linear harmonies (P, N, and IN).

    The German augmented 6th in measure 1 is clearly prolonging tonic with neighbor motions in both the soprano and alto; notice how the bass and tenor do not move at all. (The chord marked "X" will be explained in Chapter 37.)

  4. Augmented 6th chords can be used with secondary goals (harmonic areas other than dominant), either alone or in combination with other chords.

    Chopin not only uses the raised ^4 in the bass, but due to a sequential-like motion, repeats the first full measure down a step in the following measure, creating a secondary motion to the subdominant.

  5. It is possible to find augmented 6th chords with scale degrees other than those found in the Italian, French, and German varieties. It is tempting to apply still more nationalities to them, such as the Swiss augmented 6th or the Polish augmented 6th, but that urge will be resisted and a simple "+6" symbol will be used.

    This famous excerpt has been a topic of discussion since it was written in the 1860's, but the second full measure clearly shows a lowered ^6 in the bass and a raised ^4 in the alto (hallmarks of an augmented 6th chord in A minor). The ^2 in the tenor might be indicating a French augmented 6th, but the problematic ^7 in the soprano confounds. There are some who maintain the G# is merely an appoggiatura which ultimately resolves to A at the end of the measure, creating a true Fr+6; it is difficult, however, to ignore the sound that dominates most of the measure.

The extensions above are exceptional and are not the norm. In synthesis exercises, stick to the normal situations. In analysis exercises, be prepared for anything, and explain the unusual items.

34.6 CHROMATIC HARMONIC ANALYSIS

As in the previous two chapters, analyze the example in the box below:

  1. The sonority is A - C# - Eb - G
  2. The quality cannot be categorized
  3. The scale degrees are Re - Fi - Le - Do
  4. The previous two steps indicate an augmented 6th chord
  5. The chord comes from minor dominant and moves to true dominant
  6. It is a French augmented 6th

Do the same thing again with the following example:

  1. The sonority is F# - A - C - E
  2. The quality is dm7
  3. The scale degrees are Re - Fa - Le - Do
  4. The previous two steps indicate a borrowed chord
  5. The chord comes from substitute for tonic and moves to dominant
  6. It is a borrowed supertonic 7, in first inversion

CURRENT CHROMATIC VOCABULARY:

ASSIGNMENTS:

ANALYSIS

Provide a Roman numeral and Schenkerian analysis for the following pieces in Music for Analysis:

  1. Mozart: Sonata, K.457, III [#276, CD track #66]
  2. Beethoven: Sonata, op.109, III [#277, CD track #67]
  3. Verdi: La Traviata, Act III: Prelude [#286] Listen to a performance
  4. Schubert: Symphony in C Major, II [#287]

SYNTHESIS

Add a soprano, alto, and tenor to this figured bass, and a Roman numeral and structural analysis. When that is done, do three more things:

  1. Put the bass, tenor, and alto parts in the bass clef, in close position
  2. Figure these three parts into an Alberti bass; this figuration will stop with a block chord on the final tonic
  3. Add multiple embellishments to the soprano part, using only quarter-notes, with at least

To prepare this writing assignment properly, use the notation guidelines appendix, located at Basic Principles of Music Notation, Semester III.


Links to chapters in this unit:
Chapter 32. Borrowed Chords
Chapter 33. Neapolitan Triad

Link to previous unit: LARGER PERSPECTIVES

Link to next unit: CHROMATIC PROCEDURES III: Advanced Vocabulary


Copyright 2008-2009 by Phillip Magnuson.

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