John Mayer went four months without uttering a word after doctors ordered him to rest his voice.

The rocker has suffered numerous problems with his throat over the years and underwent surgery to remove a granuloma from his vocal cords last August (12).

He has now revealed that during the height of his problems, he had muscle freezing agent Botox injected into his vocal cords and went months without talking at all, using an Apple iPad to communicate instead.

Mayer tell Billboard, "I probably had contiguously three, maybe four months of not saying a word. The endurance was tough for me, but I started a new life."

However, he hated having to rely on a gadget: "I was forced to type on my iPad to communicate anything. It wasn't liberating. Is breaking your leg liberating? No. All complexity is gone when you don't have a choice."

Mayer is now back on track after his surgery and is heading back out on tour this summer (13), and the rocker insists he is delighted to be able to sing again: "It's hard to believe that I'm healed, but just to make sure, I keep going back (to the doctor) every two weeks for a look, and it's the same - if not better."