[Her reaction doesn't sit well with him at all, and he's almost hesitant to explain further.]

It's a rhythm of four - almost like a Time Lord's heartbeat. I haven't heard what he's hearing, but he was able to replicate it into a subliminal phone signal. Was able to find it that way - it was how he won the Prime Minister election on Earth. But that's so very much him. Forcing people to partake in his own madness.