Personally, I think Sylar could hear what was going on, but why should he really care? He is essentially unbeatable now, and even if the guy did use his power on him, I'm sure Sylar could have avoided it somehow, probably using telekinesis. I originally thought that he would use telekinesis to stop Claire from falling into the hole, which would have been a little cooler in my opinion than his weird teleport grab (wasn't he on the other side of the room to begin with? With Noah? And then all of a sudden he is helping Claire? I dunno.).
Hmm, maybe he activates super-hearing by straining to hear it? Like, that's a subconscious trigger to turn it on? I would buy that explanation.
I also thought that Sylar's whole 'knowledge hunger' is kinda stupid, but at least it explains my biggest gripe about him from Season 2 (why he seemed to be some kind of vampire, but one that eats brains).
To be honest, I was hoping Bob's power would get more use, but I read something online that he was supposed to turn a wooden door into a metal one, but the effect 'looked like crap'. But they also said that they hoped to expand on his powers now that Sylar has them.
