Audio jumps to full volume or mutes randomly

I'm on 14.04 and I get volume spikes randomly. I first noticed it only when using Spotify so I thought it was a software issue with Spotify, now I've started it noticing sometimes when playing through flash as well so I'm thinking it has more likely to do with pulseaudio. Please help me troubleshoot this. What commands can I run to get you the information you need?

Update: I've now started getting the audio muted randomly and I haven't noticed the spikes in a while. There's nothing that I've done, no settings I've changed. But this is even more annoying since I used to be able to max out the volume in Ubuntu and control it with my external speakers instead, but when it get's muted there's nothing I can do to workaround it. Thoughts?

I had experienced exactly the same issue on my Debian Stretch some hours ago. If I read this report correctly then it seem that there are bugs with some motherboards and pulseaudio.

Follow this comment to verify in pulseaudio log that your problem is related with flaky jack sensing. If so then you may find other comments on that bug report helpful:

Change /usr/share/pulseaudio/alsa-mixer/paths/analog-output-headphones.conf from:

[Jack Front Headphone]
required-any = any

[Jack Headphone]
required-any = any

to :

# [Jack Front Headphone]
# required-any = any

# [Jack Headphone]
# required-any = any

[You'll have to] restart pulseaudio (or the computer) for changes to take effect.

and:

There might actually a better solution in newer kernels: if you install the daily DKMS package you will get this too. Then edit /etc/modprobe.d/alsa-base.conf and add this line:

options snd-hda-intel jackpoll_ms=250

[And] then reboot and test. In case the sound card is not the first hda intel sound card, you might need to add more, like this:

options snd-hda-intel jackpoll_ms=0,250

or:

options snd-hda-intel jackpoll_ms=0,0,250

... depending on which card you want to change.

This bug was reported in 2011 but comments from 2015-12 as well as my own issue confirm that it's still present.