@advocatux Thanks, but it didn't change. I tried all the settings, it changes with a audio recorder, but does not change anything while phonecalls.
Testsetup: call another phone close to you, turn off the other phones micro and listen to your speach. If you speak directly to the spaeker it's fine, if you turn the speaker a little bit away it gets disturbed.
Seems that phonecalls use the microphone differently than multimedia apps.
I think i will write a bugreport as this is one of the core functions of a phone.