Pop singer Adele announced on Tuesday that doctors have advised her to cancel the remaining dates on her US tour to give her voive a break.  "My voice is weak and i need to build it back up," the singer said in a statement on her website. "I'm gonna be starting up vocal rehab as soon as, and start building my over all stamina in my voice, body and mind."  The canceled dates run from an October 7th stop in Atlantic City, New Jersey through the 21st in Grand Prairie, Texas.  Adele says the dates will be rescheduled, although makeup dates have not been determined.