For Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:plater/Tumbleweed/home:plater.repo
zypper refresh
zypper install audacity
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:plater/16.0/home:plater.repo
zypper refresh
zypper install audacity
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:plater/15.6/home:plater.repo
zypper refresh
zypper install audacity