Videoconferences - seeing the face of just one person when there are several (say 50)

I will be having a videoconference with several people (possibly 50) but I don't want 50 little faces on the screen as no one will see them. Can you put in a "speaker view" option or something so we can only see the face of the person who happens to be talking at the moment? Right now I understand there is nothing like this????????