code: def loudness(self):
          
          response = self.renderingControl.GetLoudness([
              ('InstanceID', 0),
              ('Channel', 'Master'),
          ])
          loudness = response["CurrentLoudness"]
          return bool(int(loudness))
docs: bool: The Sonos speaker's loudness compensation.
  
          True if on, False otherwise.
  
          Loudness is a complicated topic. You can find a nice summary about this
          feature here: http://forums.sonos.com/showthread.php?p=4698#post4698