Holophonics are binaural recording system created by Hugo Zuccarelli. Holophonics are based on the assumption that the auditory system acts as an interferometer, where electromagnetic waves are superimposed in order to extract information about the waves.
3D holophonics relies on phase variance, just like stereophonic sound. Holophonics sounds are most clearly heard through headphones, though can be demonstrated to be effective with 2 channel stereo speakers, as long as they are phase coherent.
In a 1983 article on the New Scientist, Hugo Zuccarelli stated that the human auditory system is a sound emitter, producing a reference sound that combines with incoming sound to form an interference pattern inside the ear. The nature of this pattern is sensitive to the direction of the incoming sound. According to the hypothesis, the cochlea detects and analyzes this pattern as if it were an acoustic hologram. The brain then interprets this data and infers the direction of the sound. Recordings released using Holophonics include Pink Floyd’s “The Final Cut”, and Roger Waters’ “The Pros and Cons of Hitchhiking”.
You can experience binaural tones at home on Mind WorkStation (free trial, and 10% discount on purchase) and Neuro-Programmer (free trial, and 10% discount on purchase).