'Send ``mute_changed`` event to all mixer listeners.
This method should be called by subclasses when the mute state is
changed, either because of a call to :meth:`set_mute` or because of
any external entity changing the mute state.'

def trigger_mute_changed(self, mute):

    logger.debug(u'Mixer    event:    mute_changed(mute=%s)', mute)
    MixerListener.send(u'mute_changed', mute=mute)
