I had the same problem after upgrading to 8.10, below are my notes from fixing it. These steps worked for me. However, I have the nagging worry that maybe I didn't have to go through all of it (the steps 1 to 5) and that maybe I just had to futz around with the volume levels and other settings to get everything to work. So maybe try the stuff after step 5 first. What seems to have fixed sound after it didn't work after upgrade to 8.10:
From https://wiki.ubuntu.com/PulseAudio did: Go to System -> Administration -> and click on Users and Groups.
Click on Manage Groups, and scroll all the way to the bottom of the list where you will find: * pulse-access * pulse-rt Make sure to highlight each, one at a time, and click Properties. Just put a check next to each user that you want to be able to have access to sound. For example, there's "ted" and "root" and "kamilion" listed, and you only want "kamilion" to have access to sound, that's the one to check, leave the other two blank. Note: The "pulse" group is for pulseaudio internal use, and normal users should not be added to this group. Then did: 2. Configure libao applications to use PulseAudio: Code: $ echo "default_driver=pulse" >~/.libao 3. Perform the following steps to remove obsolete configuration files, ensure "libflashsupport" is not installed & you have the all the necessary packages up-to-date: Code: $ rm -r ~/.pulse ~/.asoundrc* $ sudo apt-get update && sudo apt-get dist-upgrade $ sudo apt-get remove libflashsupport $ sudo apt-get install libasound2-plugins padevchooser libao-pulse libsdl1.2debian-pulseaudio NOTE: Choose Yes to allow unsigned packages to be installed. 4. Go to System/Preferences/Sound. Set all "Sound playback" options to "Autodetect", and set "Sound capture" to "ALSA". 5. Reboot for changes to take effect! Then had to use: alsamixer -D hw:0 and turn up pcm volume to get sound. Recording still didn't work from the built-in mic. Also, the volume icon vanished somewhere along the line. Brought it back by going to the panel, right clicking and hitting add and adding it from there. Once it was there, right clicked on it and went to "open volume control". Go to preferences for each item in the dropdown and check everything. What seems to work is, under HDA ATI SB (Alsa Mixer), the volumes in the recording tab can all be all the way down and the device not set to be a recording device, under the switches tab though, it seems to be pretty important that analog loopback is unchecked. In the options tab, digital input source should be set to digital mic. Under HDA ATI HDMI (Alsa Mixer), IEC958 should be unchecked Under Sigmatel STAC9205 (OSS Mixer), it seems that the in-gain level is not important, as long as it isn't muted. Capture: Monitor Source of ALSA PCM on front:0 with toggle input source from master toggled on, unmuted and turned up Capture: ALSA PCM on front:0 (STAC92xx Analog) .. volume turned up, unmuted and master toggle on. Doesn't seem to matter what the volume level is, but it does matter if it's muted.