Crackers/cracking back both sides

Hello. I’ve had a clapping noise in the back for a few weeks. If I’ve been on uneven roads until, or it gets a bit bumpier, then a clearly understandable “Klarack Klarack” comes from behind. I have the new “Antipolter”-steamers in there for two weeks. So it can’t come. Yesterday I also changed the back seat because I had a little suspicion of the locks. But that wasn’t. I mean that it would have to come somewhere at least from the direction there. Could it be something with the belts? Somehow it’s annoying. Now I finally got rid of the poltern, now you can hear this all the better for this. If someone else has these sounds and maybe knows what it is, he can get in touch. Oh well, maybe still to the car. New A3, 07/04. Now 11TKM down. New dampers in the back because of polterns. Thanks already Bernd