I don't have any information BUT he sounds an awful lot like my stepfather who has an upper partial plate to replace four front teeth.
A year ago or so I thought Bridges was sucking on hard candy, perhaps because he is otherwise a chain smoker. But as the characteristic persists throughout the Tron - Legacy film this no longer seems reasonable.
Whatever the source of this eccentricity, Jeff Bridges has repeatedly touched me through films like The Fisher King and Crazy Heart.
I too have been wondering what's going on with his speech. I've been a fan of his since he starred in the King Kong re-make and he never had this impediment in the past, just in his more recent movies. It makes him sound a lot older.