Hey, I just ran into the same issue and resolved it on Ubuntu by installing `pulseaudio`. I'm honestly not the most sure of specific installation instructions, but I ran something like:
```
sudo apt-get install libpulse
sudo apt-get install pulseaudio
pulseaudio --start
```
and then my system's device output changed to something random -- I had to change it back to my headphones. But after that I can hear sound!
Something that was useful in debugging was running this to ensure `pulseaudio` was working:
```
paplay /usr/share/sounds/freedesktop/stereo/complete.oga
```
^ just plays a nice ding sound that succeeds if the audio is set up.
