I've installed Ubuntu 12.04 LTS from a minimal cd on a netbook (Asus 1001 PXD). I've installed the ubuntu-desktop package using the --no-install-recommends option. Everything works fine, except the "sound test" for headphones or analog speakers. Clicking on the "test" buttons (front left and front right) I don't hear any sound. Despite this, the audio is working properly. I've checked the audio levels with alsamixer; I have also checked that the test sounds actually exist in /usr/share/sounds/alsa. I tried an installation of Ubuntu 12.04 LTS made with the desktop-cd, and in this case the speaker test works properly. I suppose, therefore, that the problem could depend on the lack of a package, but I have not identified which one.