yesterday i started hearing a loud vibrating sound while driving to my aunts house. it sounded like it was coming from beneath the radio, i couldnt tell if it was something on the interior or the exterior making the sound. i didnt feel any vibrations in the pedals or the stick. whats making me think its on the exterior is that my brother tried driving a stick for the first time today so it went through a bit of rough driving. after we switched seats and i drove home i didnt hear the vibration at all. anybody have any suggestions? anything i should check that could be loose?