Today a new problem cropped up in my HP Probook 430 G3 with Ubuntu 14.04. I noticed that my earphones and speakers were simultaneously playing so I tried out various options from here on AskUbuntu threads like Auto-mute options in alsamixer and gnome-alsamixer. I also tried to add the following to alsa-base.conf and restarted.
options snd-hda-intel model=laptop
options snd-hda-intel position_fix=1 enable=yes
After restart all sorts of problems started with weird static and beeps at startup so I removed these lines and restarted. Now on reboot there is a static on speakers for about 3-5 secs before the Ubuntu boot animation and then it goes away. Now whenever I plug in my earphones there will be a constant static, no sound from speakers and no response to changing anything on alsamixer like volume levels or mic boost or anything else.
I have tried reinstalling alsa-utils using apt-get but to no avail.
Best Answer
I think the problem has gone away now. At least it has not surfaced since last 5 restarts. It was solved by a combination of steps mentioned in the question and restarting at each step.