Comment 62 for bug 472770

A moment ago I discovered that installing Gnome ALSA MIXER solved the problem on my computer.

To all it concerns : Please try this turnaround.
Adjust the audio level in the Alsa Mixer on channel named VIDEO.

There seems however to be a slight delay between the time when the slider is moved up/down and the time that audio level starts to increase/decrease.

The keyboard volume buttons +/- should also work, but also with some time delay.

It would be nice to report your own results here.