2013 f350 sony sound system rattel
 

I just purchased a 2013 F 350. It has the sony sound system in it. It sounds great on fm radio or my i phone when I play music from it but on the AM radio the speakers have a rattle in them when certain announcers talk. I took it to the dealer and they brought out another truck to see if other systems did the same thing and it did. It is very annoying. are all the new sony systems like this? Is anyone else having this problem?