Do you want to change your LOGIN and LOGOUT sounds in Ubuntu? If yes then, you just need to convert your music file to ogg format.
Now write the following command in terminal :)
sudo chmod -777 /usr/share/sounds/ubuntu/stereo
Browse to /usr/share/sounds/ubuntu/stereo folder and backup the desktop-login.ogg and desktop-logout.ogg. Copy and paste your .ogg format created music files into this folder and rename to desktop-login.ogg and desktop-logout.ogg.
You can follow above steps for all types of Ubuntu Sounds.
Thank you :)
