Comment 7 for bug 1622844

  // , Found a workaround.

Open a terminal by pressing ctrl+alt+t. Experiment with different bars in there by using the right and left arrow keys to select a speaker or item. Once you've selected a likely one, use the up and down arrows to change the volume.

https://askubuntu.com/questions/695830/no-sound-ubuntu-15-10-intel-audio-driver-via-vt1708s