I followed these instructions.
"(1) Double-click the speaker icon in Ubuntu's system tray and click Edit -> Preferences in the Volume Control window that appears. In the list, look for the Master Surround entry, and put a checkbox in it. Then look for External Amplifier and put a check in it. Click the Close button then click the Switches tab in the Volume Control window. Remove the check against External Amplifier.
(2) Then click the Playback tab and click the Speaker icon beneath the Master Surround slider, so that it's no longer muted. Then adjust the slider. Playback some audio and you should find everything now works. Basically, the Master Surround slider is now your volume slider. Weird, but true. To make the system tray applet use the Master Surround to control the volume, right-click the system tray speaker icon, select Preferences, and select Master Surround in the list. "
But I went into System> Preferences> Sound, because it wouldn't let me double click like in the instructions. I got a window open with 3 Tabs Devices, Sounds and System beep. I can't find the Master Surround entry. but all the playbacks are set to Autodetect and the sound capture is ALSA - Advanced Linux Sound Architecture. I tried to test them but it just closed the window and did nothing.
Thanks.
Visit my other thread for information.
http://ubuntuforums.org/showthread.php?t=521226