Keith Urban became terrified he was ruining his voice by singing in his sleep after a dream.

The country music star had an operation to remove a polyp on his vocal cords in 2011. Recovery meant he had to be completely silent for three weeks. He wasn't allowed to talk, cough or sneeze, which he found incredibly hard.

Eventually being so quiet began to get to Keith and he started having lifelike dreams in which he was singing.

"I woke up the next morning and I called the doctor and asked, Would it be possible that I could sing in my sleep?' cause you can't, you're not allowed to, and I was terrified that I was singing in my sleep, singing Leo Sayer songs," he laughed.

Keith is married to Nicole Kidman and they have two daughters together, Sunday Rose and Faith Margaret.

Not being able to make noise presented its own problems when it came to the star's family.

"Not being able to talk for three weeks, that's a long time. If you have to engage in some sort of heated discussion, the other person can talk and I just have to write," Keith told Access Hollywood.

"[Sunday is a toddler and] can't read, so I had that issue too Mum had to communicate."

Keith has premiered the promo for his new track You Gonna Fly. It follows him while he is playing a series of shows and he hopes it shows fans what being a musician is all about.

"It was just a way for us to capture the tour," he explained. "I think you get a really good sense of what the tour was and what happens on the road, live."