Noise coming from power adapter

Okay, I need to figure out what's going on, I've been using my laptop since last night, and didn't notice it before, but right now it seams like my power adapter is making noise. It's kind of like some static. I'm charging my macbook (and using it), so I'm obviously pushing the adapter to the limit. However I never heard any noises from my deceased iBooks adapter. the sound is barely audible when the adapter is a few feet away, but obvious when you put it near your ear.

Does anyone else hear noises like this from their adapter? I'm just kind of afraid something might be bad with it, and fear a capacitor exploding or something. I know the adapter also gets very warm, but that's no different than the ibooks did.

Phil