You won't be hearing much from Miley Cyrus over the next few weeks—unless she decides to ignore doctors' orders. Sources tell People that a longstanding but previously undetected problem with the singer's vocal cords was found when she was hospitalized for tonsillitis last month. She had vocal cord surgery to correct the problem and the recovery process will involve several weeks of silence, meaning she has had to put singing—but not songwriting—on hold, the sources say. It's not clear when Cyrus had the surgery, but she said in late October that she was on "vocal rest," Rolling Stone reports. On Friday, boyfriend Cody Simpson posted a picture of the couple with the caption "Success." (More Miley Cyrus stories.)