Middle 8 Confusion in "Yesterday"

This is a terrific question, and could be stated more broadly: Does a bridge always have to end on the dominant function? If not, and it ends on its tonic, what makes it "work" since it's going against the tried and true formula? And those examples: Something, Help, Hey Jude, Back in the USSR, Love Me Do... let's think about how the "bridge" is being used in these.

The main thought I have, after reviewing these tunes, is that the bridges, while providing substantial contrast, also are acting a bit like a chorus, because of the perfect cadence resolution. For example, the "Something" bridge is highly contrasting and in a wildly different key. The "Yesterday" bridge is less contrasting, and feels like a "follow up" idea. "Help"'s bridge is clearly a chorus.

What I learned from this question, and from attempting to answer it, is that there is a gradation between bridge and chorus, and the masters are aware of this and use it, and I don't and I probably could. Thank you!

I would say this song doesn't have a middle eight, but that isn't really important, because you really just need a way to look at form.

The important thing to look for regarding traditional form is tonal center and phrase endings.

Let's look at a basic 32 bar song form...

32 Bar Form

A  : I ... V, 8 bars
A' : I ... I, 8 bars
B  : ? ... V, 8 bars (the bridge)
A' : I ... I, 8 bars

The song Over the Rainbow is an example. The A parts use the same basic melody and only the endings change. Ending on V for the first repeat propels the music into the second. When the melodic material is reused like this the technical term is a parallel period. The periodic structure allows for repeating the basic melodic material without it becoming played out.

The B middle eight also uses the period device - it ends on V - but it starts with some harmonic contrast. I indicate that with ? to show it could start from any number of chord. It will often be in a new key. It also is typical for B to get new, contrasting melodic material. With three repeats of the A melody the B section needs to provide something new in the 32 bar form.

So, in 32 bar form periodic structure (the alternate endings on V and I) propels the music forward and the B section provides harmonic and melodic contrast.

Now for the structure of Yesterday...

Yesterday

A :  I ... bVII7 IV I, 7 bars (1 + 2 + 2 + 2)

B : IV ... ii V7 I, 8 bars (4 + 4)

A A B
A B
A B
A coda

Setting aside the famous 7 bar length of the A section, the structure is basically 8 + 8 bars with A starting and ending on the tonic and B moving from some tonally contrasting area back to the tonic. This is a very common form where the two sections often just alternate like ||: A | B :||. Often there is melodic contrast between A and B. Unlike 32 bar form the endings are both on the tonic. But there is some similarity between the forms in that B starts with harmonic and melodic contrast.

You could sort of view this simple form as a kind of modified truncation of 32 bar form...

I (... V, I) ... I, ? (... V, I) ... I

...where the parenthesis show us dispensing with the periodic endings and strong melodic contrast in B. It's just 8 bars repeated where the second part starts on a new harmony and with some change in the melody.

Many songs in this simple 8 + 8 form will have a sort of 4 + 4 bar split of the A section with a pause on V which makes it feel like a miniature of periodic structure. I looked through my songbooks for an example that didn't do this and found the spiritual Steal Away. It's 8 + 8 bars, both A and B end on the tonic, B starts with the contrasting harmony and melody, no internal pauses on V.

In my opinion Yesterday doesn't use a middle 8. It's written in a different form. But it still exhibits the typical elements that delineate sections.

One final observation. The two endings in Yesterday offer a nice contrast even though both end on the tonic. The first one is a kind of "modal" ending using the bVII chord and a plagal cadence. Harmonically that contrasts with the B ending using a traditional ii V I. That's nice way to set the two sections apart but still follow the basic conventions of the form.

You're confusing 'what a middle 8 often does' with 'what a middle 8 HAS to do'. Either re-define your private definition of a 'middle 8' or give this one a different label. Preferably the first.

It obviously does work! What reason could there be that it doesn't? There is nothing in the 'rules' that says there must be a dominant before starting the next verse. True, there often is, but that's no criterion.

In fact, there are several songs where the middle eight/bridge ends on tonic, but the next verse starts somewhere different!

The reason so many songs finish on the dominant is straightforward - that leads the listener to expect a tonic, therefore probably the next verse (which often starts on tonic) will begin. But that's part of the art for songwriters - don't always give the listener what's expected. And that's most likely why those sort of songs stick in the memory.

The middle 8 or bridge of a song is there to provide some contrast to the song but it doesn’t have to end on a dominant even though it often does. In fact there are no rules governing how a bridge should end, it is up to the composer. In the case of the Beatles bridges end on the tonic fairly regularly:

Something

Help

Hey Jude

Back in the USSR

Love Me Do

I think the reason it works is the same reason consecutive verses that start and end on the tonic work. There is a resolution, it just happens within the section instead of as a lead in to the next one.