How to install Audacity 2.1.0
Solution 1:
Run these commands in a terminal
sudo add-apt-repository ppa:ubuntuhandbook1/audacity
sudo apt-get update
sudo apt-get install audacity
Source: http://ubuntuhandbook.org/index.php/2015/04/install-audacity-audio-editor-2-1-0-in-ubuntu-from-ppa/