Figuring out a modulation

Question

I am currently working on a piano piece and am at the same time trying to analyze its harmony.

I am puzzled by a small section where it seems to modulate from C major to C minor, but everything doesn't seem to work from a theoretical point of view (to be more precise, it doesn't seem to fit from my perspective, which is not professional at all).

On measures 13 and 14, the melody played on measure 11 and 12 is repeated, with an Eb instead of an E to suggest the tonality of c minor.

However the bass part, from my point of view, seems to be a deceptive cadence in Eb major, which lands on C minor. I assume it is a way of modulating whithout using a dominant seventh chord.

What bugs me is that, if we add up the bass part and the melody at measure 13, it makes an Fm7 chord with an Eb at the bass. This chord would make sense in C minor, but not in Eb major (the key of the deceptive cadence).

On top of that, if we in fact assume we are already in C minor at this point, the next chord (measure 14, Bb major) doesn't make sense because in C minor, there should be a B natural. Right ?

Sorry for the sloppy explanations and conjectures, but I could really use some help with that one. Thank you in advance for your answers.

Answer 1

This isn't really a "modulation". It's fine to start out learning about major and minor scales, but in real life every scale contains all 12 chromatic notes - it's just that some of the notes get used more than others!

From measures 10 to 16, this is just a series of major chords moving in parallel: F, G Ab, Bb, C. Since C has already been established as the tonal center, this chord sequence ending on C gives the impression of being a "cadence" even though it doesn't fit any of the "simple" cadence patterns of perfect/authentic, plagal, deceptive, etc.

This sort of harmony is quite common in 20th century "classical" music (there are many examples in Debussy), as well as in popular music.

Describing measures 13-14 as a "deceptive cadence in Eb major" is correct in the sense that taken out of context, the notes could be interpreted that way, but the important aspect of music is what it sounds like, not what it looks like on paper. I don't think anybody would hear those two bars as a deceptive cadence.

Answer 2

I agree, not really a modulation. This sort of thing can confuse 'classical' harmonic analysis, but is actually very common. It's driven by melodic repetition. The phrase in bars 10-11 is echoed in 12-13, with an alternative harmony and a slight change to accommodate that harmony. An Ab chord includes C, the tonic note, so is an obvious candidate for re-harmonising that note, the strongest note in the phrase. Having established Ab, what could be more natural than to try walking home to C via Bb? Yes, that sounds good! Don't worry too much about WHY, or about what notes are 'allowed' in any given tonality, just stick it in your list of 'things that sound good'.

(You might be surprised how many ways the tonic (or dominant) note can be harmonised. Do you know 'One Note Samba'?)

Here's some nice music.

Answer 3

I haven't taken the time to play this piece because the piano is in the other room but this is what I see:

From mm. 9 - 12 there is a clear C major phrase from I (mm. 9 - 10) to IV (mm. 11 - 12) to V (mm. 12).

From mm. 13 - 16 it does move to C minor by way of the bVI chord (mm. 13, Ab chord, (Ab C Eb)). The next chord after Ab is then the minor v chord: G Bb D F (with the G omitted in this case) which then resolves back to I (C major).

The key to this analysis is the bVI chord (Ab major) which comes from the key of C minor. There is thus some mode mixture in this short piece. You also mentioned that mm. 13 could be Fm7. You have hit on what Jean-Philipe Rameau termed the Double Emploi: the chord can be taken as Ab6 or as Fm7. Taken your way as Fm7 places the chord as the minor iv in c minor.