I have only heard an audible voice on two occassions and on both of those I was alone, so our cynical brethren will question whether I actually heard it or if it was my own imagination, but interestingly on both occassions His words were confirmed either by a preacher shortly after or through my devotional reading of the bible.
Apart from those I find God 'speaks' through my reading, when words seem to take on more importance to me than normal and then I usually find such words repeated in other ways, either reading or in a song or through some preaching or teaching.
I strongly believe we follow a very talkative God and He makes Himself known in many ways. Jesus said His sheep will know His voice, if that is true, why would He not speak?
Pete from Peterborough UK