flattened-seventh chord function

Question

I this post, I received some information on the usage of a flattened-seventh chord in progressions, which, along with the flattened-third, seem to be popular choices in the rock world to add flavor.

I have come across another example, and I could use some help breaking it down. The progression (in B major) is:

I - iii - bVII - V

Now, I understand that a common technique is to dip into chords from the parallel or relative minor. In the case of B minor, the bVII chord is A dominant seventh, and it is the VII chord (is that redundant? I'm not used to talking about minor keys). In the case of the relative minor, g-sharp minor, the above chord is iidim – A sharp diminished. So, either I am missing something, or there are no clues there.

Another possibility I considered was the secondary dominant chord. In B major, the V chord is F# major. So, the V/V would be C sharp major. So, that can't be it.

Finally, because this chord is featured in a descending bassline that goes: B(I) A#(iii-inversion) A(bVII) G# G F#(V), I could understand viewing it as a passing chord thrown in sort of by feeling and instinct rather than arising from consideration of the functional purpose.

Regarding function, this chord does set up the stage for the V chord nicely. I am not sure if that is a harmonic relationship (if the bVII behaves like a sort of secondary dominant) or if it is just because of the flow of the descending bassline.

I would really appreciate anyone's input so that I can lay this to rest.

Thank you!

-286642

Answer 1

This is an interesting progression, and that move from D♯ minor to A major is pretty jarring!

I understand this in at least two ways:

1. First, as you said, is the obvious result of the chromatic voice leading in the bass. We call this a lament bass, and although this is an uncommon harmonization of it, it's not completely unheard of: a famous prelude by Rachmaninoff begins with i to a III64 (!), quite similar to this example.

2. The second is the notion of an unfolding. This is more of a "scholarly" explanation, influenced by Schenkerian theory. But basically, an unfolding is when a harmony is prolonged by other chords built on the prolonged harmony's chordal members. For example: we're setting up V, as you said. The chordal third of that V is some kind of A (technically A♯), and so thus this A chord "unfolds" the V chord by arpeggiating through a type of third and then moving to the root of F♯. This interpretation is buttressed by the fact that this VII chord often functions as a dominant in this style, so obviously two dominant functioning chords will prolong the dominant function.

One other comment I want to make:

Now, I understand that a common technique is to dip into chords from the parallel or relative minor.

I would say that borrowing from the parallel minor is far more common that borrowing from the relative key. This is because the chords of the relative key are mostly exactly the same as the ones in the original key; for instance, that ii^o chord you mention in G♯ minor is simply vii^o in B!

Answer 2

The bVII is probably the most used non-diatonic chord in music. So much so that it’s the only non-diatonic chord included in Apple’s GarageBand chord palette. As for its function there are many different and valid explanations as to why it works. For me one of the most important reasons it works so well is it mimics the parallel whole step movement between IV and V chords, subdominant to dominant in either direction. We are so used to hearing that parallel sound between IV and V chords that it also sounds good and natural going to a I chord.

It is also the V of the relative major of the parallel minor (did I just write that?) Basically in your sample key A goes to D which is the relative major of B minor so it’s also sort of a borrowed cadence. When you go from A to D it’s a similar sound as A to Bm because D and Bm have 2 common notes. You’re just substituting major for minor.

There are other valid reasons, it’s like a subdominant of the IV chord, etc. There is an excellent online article about this chord here that talks about it both historically and theoretically in contemporary music, enjoy!

http://www.icce.rug.nl/~soundscapes/VOLUME22/Magnificent_flat-seventh.shtml

Answer 3

Not really an answer, but I want to add a diagram to go with @Richard's answer.

I didn't really understand the Schenkerian part, but I found a diagram that made it clear to me...

RODNEY GARRISON, Unrolling Schenker's Ideas of Musical "Unfolding". Theory and Practice, Vol. 37/38 (2012-13), pp. 111-138

In lots of rock music there are progressions like I V bVII IV :|: I... which can be seen as sequential harmony, or a IV/IV thing. I bVII I treats bVII as a kind of modal substitute of V. But those don't seem the right comparisons. I assume your progression goes ...V :|: I... in which case "unfolding" the dominant seems a much better description.

Answer 4

I've already declared in other answers (to other questions) that I interprete the bVII like a kind of suspension of the V. This theory of mine has been denied by others - but may be I can convince you ...

The use of bVII preceeding the dominant is very common in pop music. Also it is quite common to introduce the dominant by its secondary dominant and the parallel of this secondary dominant which is actually the ii7-V progression, which latter can be considered as a V with a double suspension ( do-ti and la-so = 4-3 and 9-8 )

I can hear the flat 7th (ta-ti) resolving to the 3rd of the dominant (ti) analog to the suspended 4th (do) resovling to the lead tone (ti):

So we have two similar suspensions of the lead tone: from up do-ti, from down ta->ti (whereby I ignore that bVII doesn't contain the root tone of the dominant.

I have no theoretical source than my own impression and my own experience with this phenomenon.

Answer 5

This is possibly a tangential answer, but just to make the point that the flattened seventh arguably has quite a strong relationship to the tonic compared to the major seventh...

• If we consider C as a tonic on the circle of fifths, the flattened seventh (Bb) is very close - only two fifths away - while B is way over on the other side of the circle. The Bb major chord also consists of notes all quite close on the circle to a C tonic.

• If we consider harmonic frequencies, the minor / flattened 7th is found much earlier in the harmonic series than the major seventh.

In a way, it isn't news that B is very dissonant with a tonic C - that's part of why it has that 'pull' as the leading note. But I think you could consider that it's the major seventh, and the diminished chord that is built on it in major harmony, that's the 'flavourful' one; the flattened seventh is quite tame and safely 'close' to the tonic in terms of harmonic relationship by comparison!

Answer 6

Just allow ♭VII honorary membership of the 'diatonic' club. It's been used this way in popular music for at least 50 years. Then a whole lot of special-case 'theory' becomes unnecessary.