Finally I found some information about my sound problem and a solution as well. Yesterday I tried to install the 1.0.15 version from the openSuse update repository. The system was not very happy with this decision so I stepped back to the old 1.0.14 driver.
Today I found a new how to solve this problem on the openSuse website. Sadly it didn’t worked for my Acer Aspire 4720 but at least all three alsa source packages have a uninstall feature in there make scripts:
make uninstall
So I’m back on square one. Next thing is to update the kernel to the most recent version. But I’ll leave this task for tomorrow and start to work.