🚀 go-pugleaf

Rodney Peck's description of the audio haircut sounds like an old-fashioned
"binaural" recording, which has nothing whatever to do with "holograms".
Binaural recordings which you listened to with headphones were in vogue in the
1950s, before "stereo" with loudspeakers took over.  Such recordings do indeed
sound impressive, especially if the original was done with a dummy head,
complete with realistic ears, and the microphones mounted inside the ears just
where the transducer in a human ear is mounted.  In that case, the
phase-versus-frequency-versus-location function of the recording closely
matches that of the live sound, so the brain evidently can dig the location
information out surprisingly accurately.  Someone once told me about some
experiments in which this was carried a step further--the playback transducers
were somehow installed inside the listener's ears so that there was no
additional phase shift due to the path from the transducer to the eardrum.
They said the sound was so real it was indistinguishable from hearing the live
sound.

Nowadays the same result could probably be done with a digital computer to
compute the inverse function of the path from a normal headphone driver to
the inner ear.  The fake head would still probably be the cheapest way to
compute the function at the recording microphones.

-John Sangster / jhs@mitre-bedford.arpa