On building bridges and chord changes

[jancivil]

It's a very simple I-V-IV-I progression in E flat major.

Ok here is that pesky context thing.

that is a kind of progression that doesn't lend itself especially well to a classical kind of approach, so a modulation following it that follows classical kind of principles might be kind of obvious and clunky. ie., your dominant goes to the subdominant, a rock kind of thing where V isn't as interested in being dominant as it would be 'typically'.

Does Louie Louie modulate? Does it have a bridge? I would want to absorb more from models and have some context before writing tricky songs myself.

[Ogg Vorbis]

In my own sort of casual survey of pop and jazz music from figuring out things off records or lead sheets, the shift modulation is really prevalent. When we learn things such as pivot chord modulation or common tone, these are more from Mozart sonatas and Bach preludes where the melodic material "spins" a tonal fabric which has all sorts of intriguing twists and turns.

The way song form creates tonal variety is usually less narrative and more direct in my experience of it. I think pop theory doesn't beat around the bush when it goes from C minor to Ab major for example. If you wanted to do it, you could simply go from the Cm and directly hit the dominant seventh in Ab in the measure before the change to Ab in the next section.

In pop/rock or other genres that use song form, the form kind of dictates what happens harmonically as far as key establishment is concerned. It's kind of like, "okay, here comes the chorus so it's back to Ab we go..NOW!"

So all those subtle narrative ways of modulating are interesting, but I think that they are more from a melodic development standpoint. In your song are you developing your melodic fragments and ideas or aren't you really serving song form?

I'd encourage you to no pverthink it too much and see if you can freshen up the sound in your bridge by trying new tonal areas by setting up a very business-like and no nonsense transitional movement. Once you come back to your chorus, or solo section or whatever, try to set up a satisfying return in the same no nonsense way.

I think pop genres are many times more direct forms of expression. Not a lot of ceremony and expansion. Just a bit of set-up and "BOOM" we're here now.

[JumpingJackFlash]

There is information on some types of modulation here:
An introduction to modulation (changing key)