work and others don't, this is for you. If you have no sound at all, there is a link at the end of this post for more extensive troubleshooting help but you should try this first anyway as it may solve your problem and will not make matters worse.Make sure that your system is fully updated.
Credit goes to markbuntu forum article
First you need to get some missing packages with Synaptic. These packages were not installed by default but are important for getting your sound working properly:
This is a little Default Sound Card application for choosing the default sound card for alsa.
This is a gui mixer, far easier to use than the command line alsamixer.
This is the wrapper for oss applications so they will use alsa instead of grabbing the sound card all for themselves
These are the plugins for alsa
This is the Pulse Audio device chooser and will pull in the pavucontrol which is the Pulse Audio Volume Control and papref which is the Pulse Audio Preferences along with the Pulse Audio Volume Meters.
This is the gstreamer plugin for pulseaudio
This is the package with all the restricted codecs and java and flashplayer so you can watch youtube and play your mp3s,etc..
If you have other applications like mplayer, vlc, amarok, or audacious be sure to get any extra packages available for them also.
Single command to install
sudo apt-get install asoundconf-gtk alsa-oss libasound2 libasound2-plugins padevchooser gstreamer0.10-pulseaudio ubuntu-restricted-extras
Setting things up
Once you have all these packages installed, close any application that may be trying to use sound and go to System/Preferences/Sound and set all the preferences from automatic to PulseAudio except Default Mixer Tracks which you should set to your sound card. Go to System/Preferences/Default Sound Card and choose pulseaudio.
Next, right click on the little speaker on the top panel, that is the Panel Volume Control. Click Open Volume Control and make sure it is set to the same thing as the Default Mixer Tracks. Click on Preferences and make sure that Master and PCM and whatever else you want to control are selected. Make sure that any boxes labeled SPDIF or IEC958 are not checked. Close the Preferences box. Push up the sliders in the volume control and make sure the little speakers do not have little red mute marks on them. Go to Applications/Sound and Video/GNOME ALSA Mixer and see if there is anything you missed because sometimes, for some cards, not all the
options are in the Panel Volume Control.
Go to Applications/Sound and Video and select Pulse Audio Device Chooser. This will put a little icon on the panel near the Panel Volume Control. Click on the new icon and choose Volume Control. This will open the Pulse Audio Volume Control. Go to Output Devices and see if your sound card is there, it will be listed as ALSA PCM on front:...(ALC8 via DMA or whatever your sound card is. If you have a usb device it will be listed as ALSA PCM on front:...(USB Audio) via DMA or something like that. Make sure the sliders are up and the device is not muted.
If any of the above is giving you problems, try rebooting.
Now, open Rythmbox and play something. If you have nothing handy just play one of the radio stations, you should hear something. In the Pulse Audio Volume Control/Playback you should see something like this
Rythmbox: Playback Stream and some Volume sliders that you can adjust.
More than one Device
If you have more than one device listed in Output Devices, Rythmbox may be playing in the wrong one if you do not hear anything so right click on the stream and choose move stream and move it to another device.
If you have more than one device and you want to use them all, like a usb headset and your speakers, go back to the Pulse Audio Device chooser on the panel and select Configure Local Sound Server/Simultaneous Output and click the box:
"Add virtual output device for simultaneous output on all local sound cards"
Now you can right click on the stream and move it to your new device. You should have sound from all your sound devices now or at least a clue about how it is supposed to work.
Another thing you may need to do, Check in System/Administration/Users and Groups that your users and root are enabled as members of the following groups:
This seems to be a particular problem for some people after getting recent updates.
If you still have problems look in to the following references (They are very good)