If you want to use the Illuna Mumble server, you will need to first install a Mumble client application:
For Linux (Ubuntu/Mint) open a terminal
sudo add-apt-repository ppa:mumble/release sudo apt-get update sudo apt-get install mumble
I am by no means an expert on adjusting the sound, though it is very important to run the “Audio Wizard”
Once installed, then you will need to connect to the Illuna server from the server menu. From the “public internet” server list, select: Europe > Germany > …::tchncs ::…
You will need to enter a username and then a moderator will need to add you as a registered user.
I look forward to talking to you on the Illuna Mumble server! =)
PS: Be sure to read @dotti 's simple connection instructions.