Even the most strident defenders of Christopher Nolan's Batman trilogy can't really explain the "growly voice" phenomenon. Does it make Batman sound tougher? No. Would people discover he's really Bruce Wayne if he didn't use it? No. Does it make him sound like a constipated Clint Eastwood? Yes. (BTW, free band name.)
But Christian Bale's true inspiration may actually live on Sesame Street and fail to grasp pronouns. YouTube user utubelor realized that Batman sounds suspiciously like a certain Muppet cookie monger, and we have to agree.
Watch the video of Batman conversing with Commissioner Gordon about justice and also cookies above. Were Batman and Cookie Monster separated at birth? What about Bane and the Swedish Chef?