Something is changing the sound settings automatically and sound may all of a sudden no longer be audible. This seems to happen more frequently when a monitor is connected to HDMI/DisplayPort.
I’m still not sure how to reproduce this problem exactly, and I’m also not sure how to make a workaround that will fix the problem every time it occurs. So far, however, it seems that the following may resolve the problem (temporarily):
$ pulseaudio -k
$ rm -rf .config/pulse
$ rm .cache/event-sound-cache.tdb.*
$ pulseaudio --start --log-target=syslog
Then open “Audio and Video Settings – KDE Control Center” and check the settings to make sure you use the following Audio Hardware Setup:
- Sound card: Built-in Audio
- Profile: Analog Stereo Duplex
- Sound Device: Playback (Built-in Audio Analog Stereo)
- Connector: Speakers
Hopefully, “PulseAudio Server” is now listed under “Device Preference”. Test:
- Use the test buttons in the KDE Control Center.
- paplay /usr/share/sounds/alsa/Front_Center.wav
I will have to do a bit more investigation before I can make a bug report that describes a 100% reproducible problem.