md /usr/src/realtek

cd /usr/src/realtek

wget --user rtiuser --password 9VgN4Di ftp://ftp4.realtek.com/pc/audio/LinuxPkg_5.11.tar.bz2

if the above ftp link is broken check her for the latest http://www.realtek.com

tar xjvvfp LinuxPkg_5.11.tar.bz2

http://ubuntuforums.org/showthread.php?t=1112767

http://ubuntuforums.org/showthread.php?t=843012

Digital Audio

http://ubuntuforums.org/showthread.php?t=776958

configuring alsa base

http://ubuntuforums.org/showpost.php?p=5131958&postcount=2

10,000 page guide audio problems on ubuntu

http://ubuntuforums.org/showthread.php?t=843012