Augmented 6th Chords 1. It’s a chord that contains the interval of an augmented 6th, usually above its bass Key: C major tone.

2. This interval is usually between the minor 6th degree of the scale ($6) and GRADE 8 MUSIC THEORY the raised fourth degree (#4).This Dr. Declan Plummer creates an augmented 6th interval Lesson 3: Augmented Sixth Chords (hence the name).

3. Augmented 6th chords tend to resolve outwards to the 5th degree of the scale, usually to chord V! Aug 6th V 4. So augmented chords can be another type of pre-dominant chord!

Creating Augmented 6th Chords Italian Augmented 6th chords French Augmented 6th chords • Don’t have the 5th that German • Don’t have the 5th that German augmented chords have. augmented chords have. • Instead the tonic is doubled (the • Instead the 5th is substituted for a E$ is substituted for another C) 4th (the E$ is substituted for a D) Key C Major Key C Minor • A$ - C - C - F# • A$ - C - D - F#

Gr+6 Gr+6 German Augmented 6th Key C Major Key C Minor Key C Major Key C Minor • Find the minor 6th degree of the key: A$ • Build a major triad on top of it: A$ - C - E$ • Then add an augmented 6th on top of this triad (which is also It+6 It+6 Fr+6 Fr+6 the #4 of the tonic): A$ - C - E$ - F# All notes are part of the whole • The German type of augmented 6th chord is the most common. tone scale (French impressionism) 5. Augmented sixth chords developed out of the Phrygian cadence (iv6-V in minor keys) by just adding chromatic notes to iv6. By Consecutive 5ths & Augmented 6th Chords the end of the 18th century they had become standard chords

In minor keys, only one note hi Consecutive hi Why? hi needs 5ths altered!

C minor: iv6 V iv6 It+6 V Gr+6 V It+6 V Fr+6 V 6. A progression from the German augmented 6th chord directly to the dominant chord will lead to consecutive perfect 5ths. This can be avoided by using the Italian or French versions of the augmented 6th chord, or dropping the 5th of the dominant chord, or by using a cadential 6-4 (next slide). C major: IV6 V IV6 It+6 V

Consecutive 5ths & Augmented 6th Chords Examples of Augmented 6th Chords Start 7. When resolving the German Augmented 6th chord, to avoid consecutive 5ths (called Mozart 5ths), it is common to follow this chord with a cadential 6-4!

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hi hi

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+6 +6 6 5 Gr V Gr I 4 V 3 Other Augmented 6th Chords Schubert, Impromptu Op.90 No.1 8. As described, augmented sixth chords are usually formed on the 5:42 minor 6th degree of the scale. But there are other types: 6 • based on the minor 2nd (which resolves to I or IV 4 - I) • based on the subdominant IV in major keys

Introduction to Act 1, Puccini’s La Bohéme 0:19

Ger. 6th built on the minor 2nd (A$-C-E$-F#)

Fr. 6th built on the minor 2nd (D$-F-G-B)

Modulation & Augmented 6th Chords Modulation & Augmented 6th Chords 9. Like diminished 7th chords, augmented 6th chords can be used for A German Requiem by Brahms modulation to distant keys. The most obvious way is to respell the chord enharmonically to create a dominant 7th chord (V7):

3rd mvt (cadenza), Piano Concerto No.24 in C minor by Mozart 7 6 F major: I V /IV IV 4 7:37

A few pages later:

6 6 7 7 7 A$ major: I 4 V I 4 V enharm. D$ major: I V /IV enharm. 6 7 6 G minor: Gr+ i 4 V I F major: Gr+ I 4 Modulation & Augmented 6th Chords

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A major: I V 9 I GR+ (enharm.) 7 6 o7 E$: V 5 /V vii /iii

6 7 E$: I 4 V + 6 D minor: GR (enharm.) i 4 V i