I know this is a late reply, but I never tire of learning more about the sound system in Squeak. Maybe Stéphane could wite some swiki articles on that subject. It would be extraordinarily useful to a lot of us experimenters.
As all things related to documentation, I would much prefer some live tutorial or set of examples living in the image.
I never tire of saying that, when I first discovered Squeak about 20 years ago, the image featured "The worlds of Squeak", a set of projects full of fun, surprising and wonderful demos - and where the sound system was introduced properly and nicely.
We need this back in a form or another. Nowadays, a fresh image is just a dark grey background with nothing to show.
Stef