Since 'upgrading' to 19.10, I have to do
pulseaudio -k
several times a day, because the sound system has disabled the hardware driver = no sound until doing this means it shows as available in sound settings.
It doesn't seem to happen while actively playing audio directly or in video, but does happen while those are paused.
I thought I'd already posted the fix here, but I guess not. Luckily, I did write it down in my notes for fixing post-16.04 Ubuntu:
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pulseaudio (sigh) powers down the sound card after literally just a few seconds of idle. which makes it "pop" every time it powers back ON, and gtk3's garbage code tries to use the alert sound for absolutely every bloody thing: which triggers ANOTHER pulseaudio bug, where even though the alert is muted PA powers up the sound card to NOT play it...
Edit /etc/pulse/default.pa and comment out this:
### Automatically suspend sinks/sources that become idle for too long
#load-module module-suspend-on-idle
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I needed that for a different reason to you, but my guess is it'll solve your problem too.
Desktop MATE 1.20.1 Distro: Ubuntu 18.04.3 LTS, Intel Core i7-9700K, 16GB RAM, Audio: Card: Intel Cannon Lake PCH cAVS driver: snd_hda_intel, Sound: Advanced Linux Sound Architecture v: k5.0.0-36-generic.
Did full upgrade 2 days ago to Linux 5.0.0-36-generic x86_64, and lost HDMI audio. Spent a day trying multiple "solutions". Sound now returns intermittently (pulseaudio -k, pulseaudio --start), but no "volume control" next to clock, and "test speakers" fails completely in Applications > Sound & Video >Sound.
Is this a Maté problem? or Ubuntu? Suggestions.solution please.
Thanks. Paul.
Slightly late reply - sorry - but doing the default.pa edit and rebooting does not solve the problem.
I see I didn't mention one aspect of it: switching users.
Sometimes, it's
https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/1853374 has more, with log files.