[KH]

On 6/12/2012 8:20 PM, Sebastian Kaliszewski wrote:
KH wrote:
On 6/9/2012 2:09 PM, Gary Eickmeier wrote:
[...]
Stereo has nothing to do with HRTF.
snip

Yes, that is the problem. The signal presented to the listener, in the
venue, has angular, temporal, and level clues that,

And phase as Audio Empire points out.

Well yes, but what is phase except a temporal shift?

in conjunction with the HRTF of the listener, create a spacial image.
That information was not, however, encoded into the recording except
as temporal and level information.

And possibly phase as well.

Ditto

No matter how that information is played back, the signal reaching the
listener cannot be the same as in the venue.

It will never be the same, but that's not the point. The point is
similar enough.

Well, no, the point is it still must be an illusion, because the
information is not in the recording. I agree, it only need be
"sufficient" to fool the listener. But it simply cannot be "the same".


Reflecting the sound cannot, except in the context of listener
preference, ameliorate this constraint.

It's not staright out prooven either way. But I'd say it's rather
improbable. But I'm open to be shown otherwise. That's why I wanted to
see a theory not a nice trick. Theory which would explain that the
needed clues are in the reproduced signal and distractions are either
masked or attenuated enough.

All subject to individual listener response however. Since the
reproduction *must* be different, and must present a different HRTF than
the original, it has to be listener dependent. Can you create a model
that is statistically "better"? Certainly. But then, you must
understand, that statistically, *low* bit-rate MP3's are sonically fine.
Therein lies the rub.

snip

We can't reproduce them, they are not on the recording. What we can do
is to produce an illusion, the efficacy of which is clearly a function
of both engineering efficacy and listener preference.

Yes and no. It could be like Imax-3D -- it's illusion and in fact a
simplistic one -- but majority of people, those with proper binocular
vision perceive the effect.

The "effect", yes. They do not, howefver


The "real thing" comes to us as a primarily reverberant field from a
multiplicity of incident angles.

No, it does not, except in a narrow subset of live events.

Oh, in fact it does. In majority of live events it does. You got it
wrong. In your typical concert hall critical distance is about 4m-5m. In
clubs and similar small venues it's even closer. That means that even
while one is sitting in a first row the sound of further away
instruments is dominated by reverberant sound.

I'm not thinking orchestra, I'm thinking small acoustic groups, in small
settings. Oftentimes 10 feet or less.

Many times the direct component (lets think of outside live events for
example, shall we?)

Outside events are allmost allways reinforced. So there goes that
'natural' soundstage.

Realism is not confined to non-reinforced music.

is the dominant component, and sometimes by wide margins.

Its very rare situation it's a dominant component and virtually never by
a wide margin.

In any amplified outdoor event, it certainly is.


snip
If the spacial is as important as you maintain, then reflecting the
direct portion of the signal is at least as egregious an error as
ignoring the reverberant part of the signal.

This is too simplistic.

I fail to see how, and your description below does not explain it
sufficiently, to my mind.

In fact real properly[*] recorded events are miked at a distance closer
than a typical listener is. Moreover mikes are typically high in the
air, so they get early reflections primarily just from the floor and not
from all the close surroundings of typical listener (as there aren't any
up there).

Yes, and how does reflecting these floor reflections - that arrive at
the listener from a specific incident angle - from a totally different
incident angle, during replay, provide an accurate representation?

Stereo recordings recorderd from a typical listener position
do not sound too spectacularily. This is (partly) because that sound is
then replayed at listener venue where there are additional reflections
(nobody listens in anechoic chamber). So good recording already take
into account those additional reflections. Thus additional reflections
are often 'unnatural' -- they contain peaks due to room shape and
dimensions (the incorporate replay room info), in case of box speakers
they are much damped in the highs, etc...

I would basically agree. But, "taking into account those additional
reflections" means altering the recording to account for the playback
medium and venue. Such tailoring must make the information on the
recording inaccurate relative to the acoustic in the original venue, no?
Almost analogous to an RIAA pre-emphasis and de-emphasis without a
reference standard.

Keith