John Cage's Williams Mix
John Cage's Williams Mix (1952) is an early example of multichannel spatial audio. Cage used eight single track tape machines, without proper synchronization, which was not yet invented (Gurevich, 2015). In the time of tape editing, the first ever eight channel piece of music was realized with the assistance of Louis and Bebe Barron (recording), as well as Earle Brown, Morton Feldman, and David Tudor. A paper score of 193 pages gave instructions for the editing procedure:
Splicing score for the Williams Mix.
Stereo Version
Although this stereo version does not capture the full spatial experience, it conveys the granular nature of the piece: