Ubuntu_adjusting_sound_levels

Instructions are based on Ubuntu 10.04 LTS; your mileage may vary.

The "Sound Preferences" dialog box is accessed via the pull down menu System->Preferences->Sound

Once the "Sound Preferences" dialog box displays, the "Input" tab is of more utility:

Make sure the "Mute" checkbox is not checked, and adjust the "Input Volume" and "Output Volume" levels to suit.