"Karl Uppiano" wrote in message
news:uzgNb.67237$na.39854@attbi_s04...

Is there a signal that can be generated by just 2 or 3 speakers
that
can give the listener the 3D effect? Is it theoretically
possible?
Can it be done without speakers in the back?

Norm Strong

I've been bothered/intrigued by the same thing. I played around with
binaural sound several years ago, with a very crude DIY setup, and
the
results were astonishing.

The expense and logistics of setting up a large number of speakers
(more
than two is a large number if you're married and have a typical
living room)
is prohibitive for many casual users. Speaker placement is haphazard
at best
in most setups I've seen. Finally, I think a large number of point
sources
is a poor way to set up a coherent sound field in a room. I've been
wanting
to investigate a way to do the inverse of the old M/S co-incident
microphone
setup except using speakers, but I've never tried it. The results
would
probably be disappointing, but it would be a fun experiment.

Basically it would involve only two channels, a sum channel that
would drive
a forward facing speaker, and a difference channel that would drive
side
facing speakers, all mounted on a single tower.

It's been suggested that I read up on Ambiophonics (which is not the
same as Ambiosonics.) I'm taking that advice currently. If it seems
like there's something interesting there, I'll report back. Most of
the schemes I've come across are designed to get a more concert
hall-like sound from 2 channels, and are willing to use more than 2
speakers to do it. If we limit ourselves to both 2 channels and 2
speakers things get tougher--fast.

Norm Strong