Ever read how ears work ?
If there is a dripping tap, then EEG traces show that at some point the ear simply stops sending the pulses converted to electricity to the brain. It's not your brain doing the filtering. It's the ear.
Once again, there's no need to actually research this or provide the slightest iota of proof, but I suspect the same happens with the dripping tap of propaganda. Peoples senses simply stop generating the same impulses.
This runs counter to the Goebbels argument, of course. But then the Goebbels argument was only ever about making sure Goebbels did well. Something extremists should bear in mind.