The Audacity team does not offer pre-compiled Linux binaries. Other than building from source, a third-party PPA is available with Audacity 2.2.2 packages for Ubuntu 16.04, Ubuntu 17.10, and Ubuntu 18.04.
Open terminal via Ctrl+Alt+T or by searching for ‘terminal’ from app launcher. When it opens, run command:
[rootserver ~]# sudo add-apt-repository ppa:ubuntuhandbook1/audacity [root server ~]# apt-get update [root server ~]# apt-get install audacity