I'm sorry, but I have a difficult time believing that our intelligence agencies would believe the Chinese are either so stupid or incompetent that they would not do a very comprehensive sweep for such devices before putting the aircraft into service, nor that if they were inclined to use such instruments, they would be stupid enough to use devices that would emit as much EMI as it would require to cause a "whine" during test flights, and I'm not so sure "highly advanced" devices of this type WOULD emit that much EMI. It all sounds so...improbable and fantastic if you ask me (much as communist propaganda goes).
After all, it was the Chinese who claimed a nimble jet fighter was out-maneuvered by a slow, bumbling, plane the size of a commercial airliner. Duh.