But, what happened to Jon's voice between the summer of 2011 and the spring of 2012? During concerts such as Oslo, Helsinki, London, Dublin (both nights), Bucharest, Mannheim, Udine, Vienna, Barcelona, San Sebastian and Lisbon '11 his voice was fresh, he could hit the high notes on the ballads like nothing at all, he went far out of his vocal comfort zone (additional high notes, rasp/screaming etc.) on multiple occasions...

All of that had completely disappeared by around May '12. Why?