Following an upgrade from Ubuntu Intrepid to Jaunty, I lost sound in RealPlayer. This is how to get it back.
Firstly, open RealPlayer 11 and go to Tools>Preferences>Hardware. Set the Audio Driver to OSS and untick all the boxes.
Execute the following code in Terminal.
sudo gedit /opt/real/RealPlayer/realplay
and thereafter replace the following text in Line 52,
padsp -n RealPlayer -m RealPlayerStream $HELIX_LIBS/realplay.bin "$@"
Restart the system. You should now have sound in RealPlayer 11 under Ubuntu Jaunty.