Well, I'm stumped. The only thing I can see that might be "wrong" in that description.ext is that you've got quotes around your path - that I don't think is necessary, although if you're using the default sound folder, all you'd really need to do is write the name of the .ogg file inside quotes, as so:
class Insertion
{
name = "Insertion";
sound[] = {"Insertion.ogg", db+20, 1.0};
titles[] = {0, $STRM_Insertion};
};
But it should also work if you just remove the quotes around the path initially. Anyway...also make sure you actually have the file in the appropriate folder.
Another thing that's a rather remote but nonetheless real possibility is that you've screwed up the encoding of your file somehow - you're not using i.e. Word or somesuch to edit your scripts, are you? If nothing else works, take another (proven-to-work) description.ext, edit out all the other stuff, leaving only cfgsounds, and then edit the paths there (with Notepad, for instance - or an editing programs like ArmA Edit) to your sound(s) and save it in your mission.
Sounds can be fickle beasts, I had a ton of problems just like yours when trying the first time to get them to work. But eventually the correct mix of quotes and no quotes and file formats and whatnot gave me a fully working solution. Once you've done it once, it usually keeps working no problem
Good luck!
Wolfrug out.