Comment 7 for bug 1643847

It seems that this problem is solved in libpulse0 1:8.0-0ubuntu3.2.
Reiner, I advise you to first update the package list

sudo apt update

them try to remove the package libpulse0 to reinstall the new version, by following a similar procedure (I didn't try, so it's a blind shot).

#1 purge the package
sudo apt purge libpulsedsp pulseaudio libpulse0 libpulse-mainloop-glib0 pulseaudio-module-x11 pulseaudio-module-bluetooth pulseaudio-utils
#2 keep track of the additional removed packages
#3 reinstall the pulseaudio packages to the newest version. Add at the end of the list the packages removed at step #2
sudo apt install libpulsedsp pulseaudio libpulse0 libpulse-mainloop-glib0 pulseaudio-module-x11 pulseaudio-module-bluetooth pulseaudio-utils
#4 Remove the user config file
rm -r ~/.config/pulse/*
#5 Shutdown the computer then turn it on again (don't reboot).

I hope it will help.