But the procedure involved doctors putting a tube down his throat - which they warned could have permanently damaged his vocal cords. Fallon tells Get Your Rock Out: "I knew this was a really serious thing. What really scared me was that you get put completely under and they jam a ventilator down your windpipe.

"They have to yank your oesophagus and your trachea off to one side. I was told by the doctor that I may come out of this unable to sing again. The pipe goes past your vocal cords and it's such a violent procedure that sometimes the vocal cords can get torn."

Fallon tested his voice almost as soon as he woke up from the surgery. "I kind of sat there when I came to and the first thing I did was try to hum a tune. But I was so high on morphine I couldn't tell you what it was."