[Gary Eickmeier]

"Tom McCreadie" wrote in message
...


But the DPL decoding goes on the simplified premise that all rear
hemisphere
auditorium sounds give opposing phase signals at mics, and, conversely,
that any
signals with opposing phase must always have emanated from some source in
the
rear hemisphere. Neither is true.

Consider, say, an audience member in a centre-rear seat enthusiastically
yelling
out "BRAVO !" at the end of an aria. His sound will hit the mics in
phase...so
it will _not_ display in the lower half of Audition's Phase Analysis
window, as
a pulse in the Lissajous "blob", stabbing downwards to " 6-o'clock".
Rather, it
will just register in the upper window half, pulsing up to "12-o'clock".
Likewise, in your playback room t'''hat Bravo sound wouldn't pass through
your two
rear speakers, and will not image diametrically behind your back.

It's tempting but flawed to over-milk these Lisssajous patterns for
imaging
insight.
--
Tom McCreadie

I think you are not getting me. I didn't say if a sound comes from the rear
it will show to the rear in the pattern, I said that if the pattern shows
to the rear it will decode to the rear.

There are probably many ways to encode surround sound. One is brute force.
You put a mike farther back in the auditorium or you aim a cardioid to the
rear while recording normal stereo to the front. Take that rear signal in
the editing and put it on two of your tracks. Invert one of them and pan
them right and left. That signal is now pure out of phase material and will
decode to the rear, and also show to the rear in the Lissajous pattern. So
Mr. Bravo will show to the rear in the pattern and sound to the rear in your
playback. I know because I have done it a few times.

There are other ways to force the sounds to show to the rear, such as the
stereo expander filter that I talked about above or MS done with the M as a
cardioid, or MS with excessive S in the mix. I am also wondering if a
Blumlein pair with figure eight patterns would have some surround potential.

In any case, if the recording shows a lot of action to the rear of the
pattern it will sound more spaccious and decode all around if played in
surround sound in some form of DPL which can decode out of phase stuff to
the rear.

Gary