DIAGNOSIS Debris in the wash pump or filter area. A piece of glass, bone, or hard plastic is hitting the impeller.
FIX Turn off power. Remove the lower rack. Unlock and lift out the entire filter assembly (the cylindrical piece in the sump). Check the coarse and fine filters for debris. Reach into the pump sump cavity with a flashlight and feel for foreign objects. Remove anything you find.
IF THAT DIDN'T WORK The noise could be from the drain pump if it's running continuously. Check your sink drain/air gap for a clog. A blocked drain line causes the pump to grind against water it can't move.
HEADS UP Never run the dishwasher with the filter removed or improperly seated. It will immediately damage the pump.