I've been thinking a lot about the aural css properties today--things like azimuth, pitch, voice-family, etc. that are theoretically available to screen readers.  Visual design guides are all over the place, a lot of them adapted from or comparing the web to print media.  They say things like "your lines shouldn't be longer than X characters" or "you need to have contrast between your headings and your text" or "the ratio of your line height to your font size should be X" or "don't fill up the whole page, leaving white space makes things easier to read."

But I've been looking around and I can't find anything of the sort for aural web design, other than that you should use those properties to make your designs less terrible for people on screen readers.    You might be able to adapt from radio guidelines, if such things exist, but it doesn't look like anyone has yet.

Am I wrong?  I'm sure there are some conventions shared between screen readers for default aural stylesheets the way that visual browsers do, but I admit I haven't spent much time with screen readers.  And I'm sure some improvements you could come up with off-hand, like adding a pause before and after headings, which I suspect is one of the screen readers' defaults.  But some things don't have direct analogues to visual styles--what does a hyperlink sound like?  How about when you hover over it?  And according to Professor Bruce Walker in an Intro to HCI course I took a couple years ago, there are some things that the blind and the sighted just conceive of differently, like high vs low pitch to mean something large.

I've never attempted to design an aural stylesheet, but I'm genuinely curious now and probably will.  If you know of a style guide (or several), please let me know in the comments!