Looking at the HEROES marathon on SciFi...this show is so amazing (you can watch episodes more than once and still re-act like it's the first time seeing it).
Didn't know where to really post this theory of mine, but here it is:
Episode 16: Unexpected
With the debate about Peter using or having Eden's persuasion [FONT="][/FONT]voice power when he fights Isaac and Simone dies...that was a 'Telekinetic Voice' he used.
Telekinesis often has to be channeled through something: the wave of a hand, the blinking of an eye, a nod of the head, but Peter did none of those gestures. However, when he increased and deepened his voice, that is when/how he channeled the telekinesis and Isaac flew across the room!