In South Australia, the person who calls on the particular case (or matter) to be heard is called the clerk (in a Magistrate's Court) and Associate (in a higher court).
They do not use a gavel or say order, but simply announce the arrival of the magistrate or judge by saying, 'Silence, All stand...'
In a Magistrate's Court the Clerk takes on the role of court reporter as well as other duties while Court Reporters are used in higher courts and record information via a steno machine (pictured in the clip), shorthand (though this is less common now) or via listening to a recording of what has occurred and then typing this information at a later stage.
Witnesses do take oaths or make promises to tell the truth in court and generally sit near the court reporter.
cheers Peter