Would you recognize the sound of your own mother if she called? Not Steve Royster - the man has one of the rarest and strangest disorder known to man: voice blindness.
Like everyone else, phonagnosics can tell from the sound of your voice if you're male or female, old or young, sarcastic, upset, happy.
They just have no blooming idea who you are.
"It's not that every voice sounds the same to me," Royster explains, "it's just that hearing someone's voice doesn't bring that person to mind."
According to phonagnosia researcher Diana Sidtis, the part of the brain that allows people to distinguish things like age, gender and emotional content in a voice is different from the part of the brain that makes sense of whether or not the voice they're hearing has "personal relevance." That's the part of the brain that's able to relate to a voice and determine that it's actually familiar.
In phonagnosia, this part of the brain is damaged. This is why Royster never knows who's calling him, even when the voice on the end of the line is his own mother.
"I'm often at a loss and have to fake it," Royster says about his phone calls with his mom. "Just continue to say, 'Well, that's nice,' until [she] eventually hits on something about the house or one of my brothers, and that will clue me in that this strange woman who has called me is, in fact, the one that gave birth to me."
Alix Spiegel of (the always fantastic) NPR has the story: http://www.npr.org/templates/story/story.php?storyId=128412201