I'm not entirely sure what you're looking for (digital audio representation is a pretty vague term to me), but you could probably do worse than signing up for a course in signal processing if your university offers them. While not audio-specific, this should get you up to speed on a lot of the fundamentals of digital audio encoding.
If you don't want to follow a course, the book we're using in my class looks like it could be used for self-study as well:
Signal Processing First. Some knowledge of basic calculus and access to a copy of MATLAB (most likely your university has it installed on some of the lab computers) would probably be helpful.
Good luck, hope this helps!