I can't say anything about audio osmosis, but I did use AudioLearn...
It only gives very basic information. This is both a pro and a con because it helps to simplify the material, but also leaves you short in almost every area of the test. If you're not concerned about spending the money, I would recommend it. But definitely realize you have to study much more than what is on the CD. The OAT covers mostly basic material, so AudioLearn may have helped me more than I realize.