Are you sure you're on the right version? There was a bug with the buzz not happening in an old version, but I don't know if that was pre-b5 (the oldest on CDB). I'm definitely getting it on b6. hmm..
I'm a bit cautious to make it too loud too because it's meant to be unsettling and draw attention to the emptiness but I don't want to make it so loud it's annoying. Probably when I get better quality light buzz sounds I'll make it a bit louder since it would be less annoying at that stage.