Is it possible to interpret a conference into several languages at the same time?

Yes, it is. Several booths can work at the same time, each sitting two interpreters. At the largest event on which I have worked, we simultaneously interpreted in 12 languages – 12 booths, 24 interpreters. But generally, it is up to four languages. The listener, eg. a German receives the “ear” which is always a translation into German, even if the speaker speaks Japanese. This type of interpreting is called relay.  The German translator interprets not the speaker, but a colleague from a Japanese booth, who at that moment is interpreting a message into Polish.