P3D True Stereo (binaural) Sound

["George A. Themelis" <DrT-3d@xxxxxxx>]

Lately I have been playing with my new minidisc recorder and thinking more
and more about stereo sound and stereo photography.

Last night I bumped into this site:

http://www.binaural.com/binfaq.html

All this time I thought that STEREO SOUND meant that sound is reproduced as
heard by the ears, i.e. the left ear hears sounds coming from the left and
the right ear hears sounds coming from the right, just like STEREO
PHOTOGRAPHY.

Apparently, this ain't exactly so... I have no knowledge or experience with
stereo sound recordings (so excuse my total ignorance) but from what I am
reading, stereo recordings are created by some mixture of recordings with
microphones placed who knows where and with no attempt to reproduce natural
hearing.

On the other hand, the term "binaural" is used for recordings which
reproduce sound as heard by our ears.  This is usually done simply with two
microphones placed in the ears of a "dummy head" sitting in the best seat
of the house in a actual live recording.

While stereo recordings are optimized for hearing via speakers, binaural
recordings are made for listening through headphones.  From what I read,
listening to binaural recordings via headphones results in an astonishing
realism (feeling of "being there").  Much better compared to ordinary
stereo recordings which are really not meant to be enjoyed via headphones.
Binaural recordings are not common but can be found and purchased (they are
 more expensive than stereo recordings).

This draws a fascinating parallel with stereoscopic imaging.

First, this is funny... "binaural" is equivalent to "binocular" for vision.
 And binocular does not necessarily mean stereoscopic.  It just means
"using both eyes".  But if the eyes receive the same information, as it is
the case in many binocular instruments which are not stereoscopic, like an
(ordinary) optical microscope, then the result is a flat (non-stereoscopic)
image.  

So in sound "binaural" is equivalent to "stereoscopic" while "stereophonic"
is equivalent to "binocular".  That's interesting!

What is also funny is the explanation of binaural sound given in the web
reference above.  It starts with a stereo view.  Binaural sound is
explained in terms of stereoscopic photography!  This is funny because we
(stereo photography enthusiasts) do the same thing in reverse!  We use
stereo sound to explain stereo photography (which makes sense since
everyone knows of stereo sound).

In any case, look at the parallels:  Binaural recordings are recorded
imitating the way the ears hear, an equivalent to "ortho" stereo
photography.  Then they are enjoyed using headphones, just like stereo
images are enjoyed using viewers.  We need some way to put the left image
to the left eye and the right image to the right eye.  Same for sound.  You
need headphones or just stick the left speaker to the left ear and the
right speaker to the right ear and try and block crosstalk.  "Crosstalk"
(leaking information from the right channel to the left) is what is known
as "ghosting" in stereo projection.

Interestingly, there is no "freelistening" equivalent to freeviewing
because we cannot direct our ears to a specific sound, in isolation, like
we can do with our eyes.

To be continued....

George Themelis