5

You can use whatever note, but we can use C. Unfortunately, I don't know what the root position would be in this case, so I will lay them out as positions. I used intervals, too.

Position 1: Root, major third,  major second, major third.

Position 2: Root, major second, major third,  major second.

Position 3: Root, major third,  major second, major third.

Position 4. Root, major second, major third,  major second.

I thought it could be some kind of augmented chord, as it has that augmented quality, but if it were an augmented seventh, wouldn't it be something like Root, major third, major third, major second?

18

As is so often the case in music, a label depends on how something is functioning in context. There are several possibilities for this chord, and they can resolve variously to (at least) chords on B, F, E, or B♭. Prepare for a bit of an onslaught!

1. A French Augmented-Sixth Chord in E

Technically speaking, your listing of Root, major third, major second, major third actually results in C E F♯ A♯, because the major second above E is F♯ and not G♭. As such, you're looking at a French augmented-sixth chord. These chords tend to move to V (here, B), and so this chord is in the key of E:

enter image description here

2. Altered V7 in F

But if these pitches must be C E G♭ B♭, then it's an altered V7 in F. The V7 chord in F major is C E G B♭. But around the middle of the 19th century, composers started making adjustments to the members of the V7 chord; typically, these adjustments allowed for a smoother resolution to I. One common adjustment was to alter the chordal fifth, either by raising it or lowering it a half step. In this case, we can view this chord as a V7 with a lowered chordal fifth, or V7♭5. In so doing, the G♭ resolves smoothly by half step to F (compare that to what is normally a whole step from G♮ to F).

enter image description here

Those two are the most likely explanations, especially if you consider C to be the bass. But there are a few other options:

3. A French Augmented-Sixth Chord in B♭

One of the fascinating things about the French augmented-sixth is that it's symmetrical: it's two major thirds separated by tritone. Using your given pitches (and not the enharmonic ones in Explanation 1), we have an augmented-sixth chord not in E, but in B♭! But this requires G♭ to be in the bass. Once again, this chord will resolve to the dominant (V), which in B♭ will be F.

enter image description here

4. An Altered V7 in B

If we combine the enharmonic spelling of Explanation 1 with the harmonic function in Explanation 2, this can be viewed as a V7♭5 in B:

enter image description here

5. A "FrV4/3" in F

We can mix these altered dominant and augmented-sixth explanations to create yet more: one is an altered dominant (much like Explanations 2 and 4) that has G♭ in the bass (like Explanations 3 and 4).

The "French V4/3" is a V7 chord (in F, C is the root) with a lowered chordal fifth (G♭) in second inversion (this G♭ is the bass). A normal V7 in second inversion is labeled a V43, but since this lowered chordal fifth makes it enharmonic to a French augmented-sixth chord, we call it a FrV4/3.

The chord still resolves to F, but now it's understood that F is tonic (like in Explanation 2), not dominant (like in Explanations 3). The resolution is the same as in Explanation 3.

6. A "FrV4/3" in B

Lastly, the harmonic function of Explanation 5 meets the enharmonic spelling of Explanations 1 and 4: a FrV4/3 in B. This looks and sounds the same as Explanation 1, but the B chord is understood as tonic instead of dominant.

  • In my ear the chord can also resolve to a B or G based tonic. – piiperi Jan 16 at 19:58
  • And it could resolve to D♭ just as easily as it resolves to G! It's a great chord, and very versatile. – Richard Jan 16 at 19:59
  • Oh, resolving to D♭6 or D♭m6, really nice! :) – piiperi Jan 16 at 20:02
  • In explanation 5, you said FrV43. I understand Fr to mean French, V to mean a chord in the fifth degree, but I'm not sure what 43 refers to. Is this a figured base notation, in which case it would be V4/3? Also, why are these chords named after the country, E.G. Italian, French and German? Thanks! – HeavenlyHarmony Jan 16 at 20:13
  • @HeavenlyHarmony Yes, the 4/3 is figured bass; I'll edit in a slash to make that more clear. The national names don't really mean anything, and they have nothing to do with the countries. It's just tradition to call them that! See also music.stackexchange.com/questions/20334/… – Richard Jan 16 at 20:16
9

If you write C7b5 a pianist or guitarist will play the right notes. Or Gb(F#)7b5.

If you want a functional description, you'll need to show it in context, HAVING a function. There's a couple of tritones in there, either of which could power a resolution in two different directions!

  • I like that you point out the tri-tone sub. +1 – ggcg Jan 16 at 20:00
4

Building off several of the existing answers, but putting it explicitly into a jazz context...

C#m7   C♮7b5    B6 
iim7   bII7b5   I6

...the second chord is the C E Gb Bb and would be a tritone substitution for the normal V7 in the common jazz progression iim7 V7 I6.


The enharmonic respelling of C E F♯ A♯ a French Augmented Sixth chord (in Richard's first example) would be the commonest functional use in 'classical' music.

Because the various spellings can be confusing, it's worth noting a French Augmented Sixth chord is an alteration of the more basic progression iiø43 V. In E minor that would be F# half diminished in second inversion, with the A tone raised. In terms of the E minor scale the 4th scale degree is altered by being raised with a sharp.

  • start with iiø7
  • put it in second inversion
  • raise the A with a sharp and resolve to V

enter image description here

It may take some time to wrap your head around the idea of augmented sixth chords, but I think it helps demystify them by recognizing their basic functions as inversions and alterations of either iiø7 or iv7 resolving to V in a minor key.

1

This is a French Augmented 6th chord (Fr⁶). Depending on the inversion used, the Minor 7th interval (C - B♭) tends to expand to an octave, while the inner voices resolve to the desired quality (ie. B Major).

1

In addition to the ones already suggested, my first-choice instinctive interpretation was:

F# dominant that wants to resolve to a B tonic chord like Bm6. It's either missing the bass, or has a tritone substitution.

or:

D dominant that wants to resolve to a G tonic chord like G6. Try it, sounds very nice! D or G# bass note fits in very easily, but it doesn't necessarily need any added bass note.

or:

Ab dominant that wants to resolve to a Db tonic chord like Db6. (Thanks Richard)

0

I absolutely don't mean to insult the other amazingly thought-out, detailed, researched and presented answers, but I am shocked that no one has posted the most natural answer (ie. the one VERY common in all contemporary, jazz, etc. music). Yes, of course you can interpret chords in any number of ways, but if you play C E G on a piano without context, and someone asks you "what's the name of this chord? It sounds happy", the correct answer is "that IS a C major triad". Answering "well MAYBE you're hearing an E minor #5 2nd inversion..." is misleading at best.

Similarly: this chord is a C7#11 (C dominant 7 with a #11 (NOT a b5)). The #11 likely explains the "augmented" quality you are noting.

In jazz (and the myriad of modern genres which inherit its harmony), "shell voicings" (the major/minor 3rd and major/minor 7th of the root) are used to define the quality of a chord (with the root note in the bass, of course). The 5th is usually left out, as it is generally not considered as "jazzy". Playing a root, major 3rd and minor 7th is a dominant chord 99.99% of the time. #11 is an incredibly common extension for dominant 7 chords.

  • I'm not buying it. Spelled as in the question title, as C-E-Gb-Bb, the chord is a C7b5. Spelled as suggested by the first interval formula, as C-E-F#-A#, the chord might be a C(add #11, #13) or some such thing. But none of the spellings provided give a C7#11, though you could certainly think of the chord this way. OP seems to have problems naming intervals, which has lead to some inconsistencies in the question. C7#11 is a good possibility given this inconsistency, but no better than the others. And, jazz players play plenty of 5ths, especially b5s. – David Bowling Jan 17 at 17:40
  • The interval formula/enharmonics given by the OP are irrelevant. They want to know the chord quality they hear from these four notes. If they don't know the chord, how can they know the correct enharmonics? #13 is as reasonable an assumption as calling the 3rd a b4. My statement regarding the trend of removing 5ths was pertaining to natural 5ths. You are correct to point out C7b5, which is another common chord, but the OP mentioned it has an augmented quality, which fits C7#11 but doesn't at all fit C7b5 (which is closer to a diminished chord). – Jase Jan 18 at 12:54

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