dvd-style commentaries and screen readers

[runpunkrun]

Hi folks, I need some help with making the author commentaries I've written compatible with screen readers. Author commentaries are story texts that have paragraphs of commentary inserted into them. In the two I've written, the only way to differentiate between story and commentary is visually and I'd like to fix that. Here's how my commentary for "Meanwhile, Back in Metropolis" is currently formatted using css. Paragraphs of commentary are set off from the story by a blue background, which I'm sure a screen reader couldn't care less about. I could easily create a div class "commentary" for those sections, but I don't know if screen readers typically announce that sort of information.

So my question is: How can I set apart the commentary sections in a satisfactory way for fans with screen readers?

Googling, I found Designing for Screen Reader Compatibility, which describes how to hide content visually while still making it available to screen readers. I could add "Commentary:" in hidden text in front of every section of commentary. But would it have to be in front of every paragraph, or is once a div enough? Would it be helpful to have a hidden "end commentary" text as well?

I only have a basic understanding of how screen readers work, so if there's a simple solution that I've overlooked, it's probably because I didn't realize it was an option. I'd appreciate your input and any suggestions you might have. I know that not everyone uses their screen reader in the same way.

Thank you for your help.