Quote Originally Posted by teaandmachines
Just wondering if I'm the only one that noticed... but if you listen to the beginning where he's like, narrating his voice is all manly but when he talks it's like "Woah, what happened?"
You are very perceptive!!
In an interview about FFX James Arnold Taylor, the voice actor for Tidus in the U.S. version mentions that Tidus goes through stages during the game, and so does his voice, i.e., the narration is a more mature, older Tidus as opposed to the Tidus of when the game starts, who has a higher pitched, younger, immature voice
http://blogger-bee.com/Downloads/stagesJAT.mp3

BTW, he and the other English actors also mention how hard it was to do voice work for this game. It seems they were told to match the character's lips (which were speaking japanese) and the overall japanese voice acting. (Japanese Tidus is even more whinny!)