For anyone, like me, who doesn't have a background in audio
engineering, this (I believe) Italian site seems pretty nice,
info-wise:
http://www.audiosonica.com/
TOC:
http://www.audiosonica.com/en/course/post/2/Index
From the site -
"The Multimedia Audio Course
is a Sound engineering course adopted by
audio schools.
The online version is completely free and under Creative Commons license."
I ran across it when googling for some info. Lots of material that
some people here might find useful. For money, there's also a
download-able premium version.
If the site has already been mentioned here, well, ok.