How to determine whether song is 16 bar blues or 32 bar form?

Question

I'm analyzing blues in the Mississippi Delta tradition and the hardest/most subjective aspect I am running into has to do with songs with measure numbers divisible by 8. For example, we can use "Death Don't Have No Mercy," by Reverend Gary Davis. Depending on how I define the measure and the time signature, each verse either fits the AA'BA pattern of the 32-bar form or a 16-bar blues. I will briefly write out the chord progression for reference:

|Em -|Am    B|Em -|Em -|
|G  -|A7   D7|G  -|B7 -|
|Em -|Em    -|Am -|C7 -|
|Em -|C7B7 Em|Em -|Em -|

|i   -|iv     V|i   -|i   -|
|III -|IV7 VII7|III -|V7  -|
|i   -|i      -|iv  -|VI7 -|
|i   -|VI7V7  i|i   -|i   -|

As you can see, the way I have defined the measure and time signature, this verse fits as a 16-bar blues. But in that 14th bar, there's a chord change within a single beat. That one measure kinda makes me want to subdivide the whole thing again and call it a 32-bar blues. Each line would therefore become 8 measures, that C7 and B7 would get their own beats, and the verse would fit the AABA melodic pattern characteristic of a 32-bar sequence. So, how do I resolve the subjectivity of time measures? How do I classify this song in a way that will be consistent with other analysts?

Answer 1

I’d like to point out that the timing of your chords on the last line is not quite right. He also plays a B in the bass of the first chord of the last line. This is what it actually is, based on this version:

Em/B C7 |B7 |Em |Em ||

The song is 16 bars, it sounds and feels like it so there is no reason to write it as 32. 32 bars would make for an unnatural fast count.

Many songs have a chord on a single beat. That is no reason to interpret the song differently but in this case all the chords are at least 2 beats each.

It is also not an AABA form. The AABA form can be any number of bars, 32 or 16 or 64, but the reason it is not AABA is that in AABA The A sections are all either identical or very similar. In this song every group of 4 bars is unique. That makes it a 16 bar blues as you labeled it initially.

Answer 2

If the overall harmonic rhythm of this piece was consistently more than 2 chords per bar, your question would make more sense. But there's only one instance here.

If the structure was:

|Em -|Am - B7 - |Em - - - |Em - - -|

|G - - -|A7 - D7 - |G - - - - |B7 - - -|

|Em - - -|G - C7 B7 |Em - - - |Em - - -|

you would have no hesitation in labelling it a 12-bar blues. I don't think adding another phrase makes it a 32-bar one.

Also:

If we're counting in 4/4 - and I hear 4 bars of 4 beats each in each line here - most chords get two beats, in that one bar it's one beat each. Not half a beat.

Check bars 13 and 14 of your chord transcription. I don't think you've got it quite right.

If you call C7 VI7 in E minor, what would you call the equally likely C♯7?