Ubuntu 18.04 is the latest version of Ubuntu LTS and possibly the most compatible and powerful version of all Ubuntu versions. But despite this, there are always certain problems with certain types of hardware or with certain configurations.
Next we are going to explain a series of steps to take in case of sound problems. A common question in the Gnu/Linux world but one that is easy to solve. Although it may seem obvious, the first step we must take is to check the sound card configuration. For this we are going to System and Sound Settings We look at which device is marked as "Output" and which one is marked as "input."
One of the most common problems is that In Output, the hdmi socket is marked and we do not want to use it. Selecting the sound card will suffice to solve this problem. There may be other problems and that through this graphic menu we cannot do it. To do this, we open a terminal and execute the following:
alsamixer
After that the management of the Alsa controller that emits the sound appears. Pressing F6 we can change the default graphics card, this can solve many sound problems, but even so, there are situations that are not solved like this. In this case, after all the above done and not working, the only thing left is to restart or reinstall Alsa and PulseAudio. To do this, we execute the following commands in the terminal:
sudo alsa force-reload
And this will restart the service and by executing the following commands we will reinstall Alsa and PulseAudio:
sudo apt-get remove --purge alsa-base pulseaudio sudo apt-get install alsa-base pulseaudio
If after performing each of these steps and even so we continue to have sound problems, we should look for a specific patch or in extreme case, change distribution or sound card. They are extreme cases that usually affect a couple of cases or with extremely specific hardware. Otherwise, any of the previous methods will help us to solve any of the sound problems that we have with Ubuntu.