Lots of special effects, on that album, via a process called, "Q-sound" among various other recording tricks/gyrations.
My favorite: the horse-drawn sleigh, that comes onstage from behind my left shoulder and proceeds diagonally, to behind the right speaker.
(Caveat emptor) GREAT ALBUM, but: I've heard poor pressings/CDs that didn't retain the info/effects (same Columbia numbers, etc).
http://www.spacial-anomaly.com/amused-to-death-by-roger-waters-an-album-retrospective/