Calling all Scion tC Owners!


I am a proud owner of a 2007 Scion tC for about 4 months now. Love the car, great all around. But i have noticed one very annoying problem in it and i need some feedback from the other tC owners. Recently i start noticing that there is an annoying noise coming out of the back whenever i am driving on a slight imperfect pavement. To me it sound like the rear hatch but i could be wrong. Its not loud, but loud enough that i can hear it easily. I didnt notice it at first because the weather was warmer and i was driving around with windows rolled down and sunroof up. But now that its getting cooler and i have to keep windows up and the sunroof closed, i can hear it loud and clear.

Now my question is, does anyone else have the same problem? If so, any suggestions of what it could be and can i fix it myself? or do i have to take it to the dealer? I thought at first that it was my license plate, so i put insulation under the plate and mounted it again but that didnt solve the problem. I will really appreciate your help guys. Thank you all in advance.