There was actually an experimental programme on BBC Radio 3 in the early 1970s where they experimented with 3D sound. With clever engineering techniques, they broadcast various bits of sound which gave the impression of sound going, not only from side to side, but vertically and laterally - behind the listener. You had to be be placed absolutely in between the stereo speakers and at a certain distance from them - but it worked amazingly.

I never heard of the technique being used in a performance situation after that, but the experiment was impressive.

Will (ex-BBC)