Muffled sound from rear bumper?

[omalak]

Ok this is driving me crazy..

Maybe I didn't notice this before, but I sure am noticing it now..

When closing Front Left/Rear Left Door i hear this muffled sound from the BACK LEFT, it seems as if it is coming from the lower bumper or wheel well area.

When closing Front Right/ Rear Right Door i hear this muffled sound from the BACK RIGHT, it seems as if it is coming from the lower bumber or wheel well area..

Now this ONLY occurs when the trunk is closed!!!

When the trunk is opened i fail to hear the noise..

The muffled sound seems as if somethng is just shaking around inside or rubbing against the bumper area.

I really cant pin it down, but it seems the sound stems from the area around the reflector area

Things i have tried:
1. Removing JACK
2. Removing tire removal tool tray from trunk
3. Removing all items in my trunk
4. Hodling onto the rear bumper real tight to ensure it is not loose
5. Holding on to the plates/plate frame to ensure license plate is not at fault
6. Locked the seat locks to ensure they were not rattling.
7. Looked under the car to see if muffler/any other part was loose (didn't seem anythng was wrong.

2008.5 GS Sedan. Is this normal!! It is really driving me crazy.. even if it is normal its just plain out annoying:bang


NOTE: you dont even have to slam the door hard to hear it, you can leave the door kinda open (you know when you close it but its not fully closed?) and if you push on the door even slightly when its kinda open the sound shows up

[rwatt]

There are flaps somewhere around the rear quarters that open when you close the door to relieve cabin pressure. It's a standard thing in most cars.

[omalak]

There are flaps somewhere around the rear quarters that open when you close the door to relieve cabin pressure. It's a standard thing in most cars.


Thanks for that bit of info.. so it is probably normal.. still annoying to hear it though... !