Susan Bennet is the voice of the original Siri. Apparently, she has a history being a voice for a machine. She was Tilly the Teller, several GPS systems and more. She recorded voice work for Apple around July 2005 for four hours a day through that whole month.
She didn’t know at the time what it was being used for, but later learned when her friend asked her “hey, isn’t that your voice?” She went to Apple’s website and found out that it was her.
Apple has changed Siri’s voice since, but it’s still cool to know that you were the original voice of Siri.