Well, I take the bible pretty literally and believe that the orginal writings were inspired by God.
I think that God, when he chooses to reveal himself, is pretty unmistakeable, at least according to biblical accounts.
I basically agree with your thesis that God hears prayer readily, although I would qualify that by saying that he only hears the prayers of the righteous. I would agree that it's rare today for God to reveal himself so powerfully, but today i think he primarily uses scripture to speak to us.
Right at the moment I'm wondering if God heard the "sound" of that last supernova that served to compress the blown off shell material into a band out of which planets can arise.
Pretty sure He heard it.