Stuck with figured bass notation for inverted 7th chord

Question

My apologies for the "name this chord" question, but i'm stuck trying to identify this harmony.

The figured bass notation indicates to me that the bass note should be the seventh of a 7 chord. The note C is a minor 7th above D or a major 7th above D-flat. The issue is that both Dm7 and D7 contain notes that aren't within the chord we're looking at. A basic online "chord namer" is telling me that what we have here is a Cmaj9/11sus2.

Can you please help clear this up for me? I'm still getting used to figured bass notation.

Thank you so much!

Please see context here (I believe it's C major, treble clef in staves 1 and 2; bass clef at the bottom):

Answer 1

TL;DR

The figured bass notation indicates to me that the bass note should be the seventh of a 7 chord.

Not quite. The figured bass means that one of the upper voices will be a seventh above the bass note. Specifically, the B is a seventh above the bass's C.

The literal chord progression is

C7  F/C  Bdim/C  C

The situation is similar to Case 2, below; the bass is suspended while the upper voices shift higher.

Full explanation

The figure 7-4-2 is indicative of a suspension and can arise in a couple of ways.

1. The 7 occurs in a suspended voice in a move to a third inversion (6-4-2) seventh chord.
2. The upper voices move over a suspended bass.

Case 2 is most similar to the chord progression in the OP.

Case 1: Upper voice suspension¹

We begin with a root position I chord. The destination is a third inversion V7 chord, but initially the I chord's third is suspended, forming a 7 against the bass, before resolving downward to complete a 6-4-2 chord.

Case 2: Bass suspension²

Now beginning with a root position V triad, the three upper voices rise to form a 7-4-2 chord before the bass drops a step to form a root position IV chord.

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^1. The example is from Figured Harmony at the Keyboard: Part 1 by R. O. Morris (Oxford University Press, 1933), page 27, exercise 4. I have transposed from the original.

^2. As in note 1, but from page 26, example 4, mm. 4–5, transposed and with my own realization.

Answer 2

The full chord progression is: C7 F/C Bo/C C

• C7 is a secondary dominant to F
• F/C is IV chord in second inversion
• Bo/C, the chord you ask about, is a dominant (Bo is G7 without G, or viio) with C, that is the root of tonic, or 4 of V chord, in the bass voice
• C is obviously the tonic, to which the dominant resolves.

How does Bo/C even work? The dominant chord includes the leading tone B, which wants to resolve to C. You normally don't want to include C already in the dominant chord, as it spoils this tension. But there are two more components: the horizontal motion (or rather lack of thereof) of the pedal tone, and cliché recognizability of IV-V-I cadence.

The figured bass notation indicates to me that the bass note should be the seventh of a 7 chord. The note C is a minor 7th above D or a major 7th above D-flat. The issue is that both Dm7 and D7 contain notes that aren't within the chord we're looking at.

The simple rule of reading figured bass is that, unless it includes accidentals, you add diatonic notes from the bass note. C, in C major with 2-4-7 means C-D-F-B – there is no doubt about it. There might be doubt about possible adding some more notes, which depends on the style and context.

Secondly, interpreting a chord in isolation is not always useful, especially not for harmonic analysis. As you can see from the discussion, you could interpret such 4 notes in many ways, but not every of them would make sense, depending on the context.

Some interesting examples of quiescenzas: