
Update (04/21/10): The information in this original post is no longer applicable since Ubuntu switched to the PulseAudio sound infrastructure. I'm leaving it all here for reference, but here's how to do it now:Step 1: open up a terminal (Applications > Accessories > Terminal or Alt+F2 and type 'gnome-terminal' into the command applet)Step 2: at the command prompt, type alsamixerYour prompt should change to something like this:Step 3: Scroll all the way to the right (using the arrow keys) until...