24-year-old singer Micah Johnson astonished the judges on 'American Idol' by delivering a note-perfect rendition of Zac Brown Band's 'Chicken Fried' -- despite the fact that his voice has been damaged by a surgical mistake.

Johnson had to have his tonsils out, and during the procedure his surgeon hit some nerves, leaving him with a speech impediment. The singer said a successful audition "would prove to me that despite the obstacles, I can still do anything."

His speech impediment fell away as he began to sing an astonishingly soulful, perfectly controlled version of 'Chicken Fried' that had Keith Urban singing along. The jaw-dropping audition had Mariah Carey visibly affected. "I was moved by your story, but even if you didn't have that story, I would have been moved by your voice," she told Johnson.

"This is the biggest fake-out I think I've ever had," Randy Jackson proclaimed, while Urban suggested, "Just sing all the time."

Nicki Minaj concurred with her fellow judges. "As soon as you start singing, you transform into a beautiful voice," she gushed.

All four judges voted unanimously to send Johnson through to the next round in Hollywood. "Life as I know it is gonna be different," Johnson said. "And it feels really, really good."

Watch Micah Johnson Sing 'Chicken Fried' by the Zac Brown Band

Micah Johnson, Auditions Long Beach ~ American... by HumanSlinky