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Re: [photo-3d] Re: Binaural Sound


  • From: "John A. Rupkalvis" <stereoscope@xxxxxxxxxxxxx>
  • Subject: Re: [photo-3d] Re: Binaural Sound
  • Date: Mon, 16 Apr 2001 11:01:16 -0700

> How interesting you record Binaural stereo when taking a stereoscopic
> picture!

> I think it perfectly complements a stereo picture and adds to the
> experience greatly.

I think so too, but apparently not everyone agrees.   Imax had earphones
attached to their stereoscopic headsets when they first introduced 3-D to
their films (the original Imax Solido system).  Conceptually, it was a great
idea.  The earphones were spaced slightly away from the ears, so that you
could hear around them as well.  Since some of the sound tracks were playing
through the regular auditorium speakers, you heard both stereophonic and
binaural sound at the same time.  Quite a sonic experience!

Unfortunately, the earphones added bulk and weight to the already heavy 3-D
imaging headgear, and (supposedly in response to complaints from audiences)
they have removed them, at least from the headsets in our local Imax
theaters.

I still think that the concept of lightweight binaural headphones with
lightweight passive polarizers is good.  Even liquid crystal glasses can be
(and are!) made much lighter and smaller than the relatively huge Imax
over-the-head sets.

The reason that Imax uses such big headsets, is that the lenses have to be
very large to cover the large screen area (they still don't completely,
unless you sit very far back).  These big lenses are heavy.  The only way
that they can keep them from falling off of your nose (or cutting a groove
into your nose) is to anchor them in the back of your head with a
frankensteinian appearing bolt that adjusts the strap in back.  The
resulting fixture does things to mod hairdo's that does not appeal to many
ladies (and gentlemen!).

They originally opted for liquid crystal because of the Omnimax dome
screens.  Most (possibly all) Imax flat screens are nondepolarizing, and
work quite well with passive polarizers.  Imax claims that there is better
cross-cancellation with liquid crystal than with passive polarizers.  And,
with the ones Imax uses, there is.  However, the image is also brighter with
the Imax passive polarizers than with the Imax LC glasses.  I wonder how the
cross-cancellation would compare if denser passive polarizers were used.

They are also talking about releasing 3-D films in their dome theaters in
the blue/amber anaglyph process (n-wave).   In any case, changes are afoot.

JR




 

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