Ubuntu 18.04 sound suddenly stopped working

Question

After rebooting my Asus ROG Strix Ubuntu 18.04 laptop today, sound no longer works - but has been working fine for over 6 months now!

I have installed and run pavucontrol and when I go to Output Devices and select HeadPhones (unplugged) then reselect Speakers, I DO get sound - but only for a few seconds.

After a few seconds have elapsed, there is an ugly "fade-out" like thing (not exactly volume-down, but also weird low-pass filter applied), and then I get nothing.

If I repeat the above process immediately, I also don't get no sound. If I wait a few more seconds, then I do get sound back but only for very little time.

I can't imagine this is a hardware issue, since I have dual-boot Windows 10, and on Windows side sound has kept on working correctly!

Plugging headphones or external speakers doesn't help at all.

I have read about removing pulseaudio and going for alsa drivers here: https://www.hecticgeek.com/2012/01/how-to-remove-pulseaudio-use-alsa-ubuntu-linux/ but I am afraid of screwing things up further when this might be a tiny stupid issue.

I've also read about the sound chip overheating, which is again weird since Windows side is OK(?): Identify element requesting sound chip to sleep

Solution

For now, problem seems to have gone away after following some instructions from here: No sound from speakers on Ubuntu 18.04

Actually, I've done sudo alsamixer, fiddle a bit with it and... now it's working; when tens of reboots wouldn't help a tad.

Comments

[user41855]

To make your speakers as your default output: askubuntu.com/a/1207638/1550967

[notzippy]

So frustrating, have same issue on new install of 19, a short (seconds) amount of audio works (but only from firefox) then tails off and no longer works. If the pavc window is open it never works. No amount of tweeking alsamixer has fixed. If I wait ten seconds without changing anything it works briefly again