Seventh chords and the key a song is written in

Question

I'm a self-learner and understands how major and minor chords are made up and how extended chords are build from these, like sus2, sus4 and 7th chords (if I'm correct, these are just embellishments of those major and minor chords). I also know about chords within a specific key and know that songs can be written in a specific key or written in such a way that it doesn't fit into a single key.

What beats me is seventh chords. Let's take the song, Black by Pearl Jam. The verse and intro has a simple progression, E7-A. They do sometimes when playing this live, change the A to an Asus2 chord (which is just an embellished A chord) every other time. If I'm correct here, the verse is written in the key of A because a dominant 7th is build from the dominant chord within a given key. In this example, E is the dominant chord in the key of A. That is how I understand it. So my progression would be V-I if I want to transpose this to another key.

The rest of the song is written in Em as there are other two progression in the song which consist of C-Em and D-C-Em

Now, if the progression in the verse was Emaj7-A, that would mean the song is written in the key of E because the 7th here which is added to the E is a true 7th degree of the E major scale. This would therefor be a I-IV chord progression.

My question is, is this info correct, and if not, why?. Also, this would mean that, if a progression have two different dominant 7th's, then that progression aren't written in one specific key but is basically a mix between diffirent keys

Answer 1

As far as transposing is concerned, it doesn't matter which standpoint you take, as long as you use the same idea in a new key. It'll all translate properly.

The E7/Emaj7 debate doesn't add up to much, either. In key E, there are often Emaj7s, but before going to IV (A), there could well be E dominant 7 (E7). Yes, that chord could be construed as "not being in E, but A instead", but it usually doesn't mean the tune is then modulating/changing key to A.There are no Emaj7s to be heard, though.

The tune sounds as if it's in A, as that's where the cadences feel at rest. So where's the C part? Parallel keys is the answer here. It's common to use chords from both the major and minor keys. So in A minor, C major appears.There's also the propensity tu use E and/or Em. By the way, the sequence is difficult to tell - C>Em or C>E. At least at one point the bassist seems to think it goes to E...

Answer 2

You can't work out where the tonal centre of a song is 'by numbers'. At least, not in the simplistic way of trying to make all the chords fit into one scale. A prime example of this is a simple blues. A7, D7, A7, E7, D7, A7. That's definitely a 'blues in A'. You have to embrace a system that can cope with the G nat and C nat. And that can let a dominant 7th shape chord not BE a dominant.

Answer 3

I've had a listen and a look at the music sheet, and I suspect A really is where the tune lives. You'll note that, on the transition to the chorus, there is a distinct shift. A full-fledged modulation? Perhaps not, but certainly a change of mode.

So, consider A as the tonic - what do you have? V - I, etc. going to IV - ♭III - v, which makes a quite logical shift to Dorian using IV as a pivot. ♭III - v confirms the mode shift. Sharp the third in v, and we're back in the verse with a leading tone to I. This all goes along with the fade-out ending (which ends on repeated D - C) - the whole chorus leaves us hanging.

So let's summarise the evidence: we have a standard dominant-tonic succession in the major; we move to the other strong tonal degree IV, and use it as a common chord pivot to Dorian mode; we hear the three chords that define that mode as well as it can be defined without direct reference to the tonic (IV - ♭III - v), which is in keeping with the endless yearning the song is trying to project; and the song ends without resolution, which is also in keeping with the mood.

Answer 4

Based on the chords I'm looking at in the song it's written in Emaj.

These are the chords it's using E, Asus2, A, C, Em, D.

1. Emaj is I
2. Asus2 is IV
3. A is IV
4. C is bVI (flat six major)- chord chromaticism
5. Em is i (key change) - chord chromaticism
6. D is bVII (flat seven major) - chord chromaticism

that is looking at it from Emaj

Now you could look at the from a key change point of view of Em

1. the C would be a VI
2. D is a VII