This addon protects you from sites that automatically play loud or annoying sounds by muting all sites that aren't specified in the whitelist. Muting or unmuting a site will update the whitelist accordingly. This behavior can be disabled on the preferences page if you often want to mute/unmute sites temporarily.
When manually adding sites to the whitelist, you can use * as a wildcard character. *.reddit.com matches all of Reddit's subdomains and www.google.* matches Google for arbitrary top-level domains for example.
In order to mute/unmute a site you can
click the speaker symbol on the tab
right-click the tab and select 'Mute Tab'/'Unmute Tab'
press ctrl+M while you're on the tab
edit the whitelist on the addon's preferences page
