I doubt anything is loose with the way the speakers hook up but I guess it's possible. It's more likely the wire going into the door is worn and breaking from opening and closing the door, and especially if you have harsh winters. If you wanna check the connection the door panel is very easy to remove, there's a screw behind the inner door handle (pop out the plastic cover) and there's a screw in the little pocket where you can set change and where you actually pull the door shut (lift out the rubber insert) all the rest is push clips so just carefully go around the edges of the door and pull until they pop (and some possibly may break) loose.
My '14 LT/RS had this problem as well.. The door chime also didn't work. Speaker replaced, on the driver side door. the static, and all were gone, but the door chime still didn't work. Another speaker. Same thing. Took it to another dealership, was told I'll need a new wiring harness. Had to be ordered. 3 weeks later, that was put in, and all was well.