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Bruce Abrams
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

As a choral singer, I regularly have the opportunity to hear what is
frequently referred to as the "absolute sound", namely unamplified music in
a concert hall. As regards this reference, we audiophiles frequently
question whether the purpose of a reproduction system is to recreate the
original musical experience in the listening room, or whether it is to
reproduce what the recording engineer heard in the control room.

Recently during a rehearsal at Weil Recital Hall at Carnegie while waiting
to get on stage, I was sitting in the third row of the mostly empty hall
listening to a sonata for piano and cello and trying to figure out
(seemingly for the zillionth time) what it was that allows the ear to so
clearly distinguish even the finest quality reproduced music from the real
thing. While the obvious factors such as tonal balance and dynamic range
certainly contribute, I began to reconsider (again, for the zillionth time)
the role that ambient sound plays. As I listened, it ocurred to me that the
percentage of reflected sound to direct was probably much greater than I had
previously thought (bearing in mind that while I was in row 3, the hall was
mostly empty) and that the quality and quantity of reflected sound probably
has as much to do with the subjective impression of "live or memorex" as
does the traditionally thought of factors of tonal balance and dynamic
range.

Back to the original question. I have always been of the opinion that an
accurate replay of the control room is all that could be hoped for, and that
assuming the engineer did his job properly, a reasonable facsimile of the
original event could be had. (The thinking was based in part on the concept
that no listening room could be made to acoustically duplicate a concert or
recording venue. This also happens to be the thinking that led to binaural
recording & playback techniques.) Which brings us to the possibility that
discreet multi-channel playback should be far more capable of reproducing
the original acoustic space than stereo ever could hope to. This is so
obvious and self-evident that I have difficulty understanding why the
audiophile community continues to disparage multi-channel systems as being
good for movies only. That stereo is physically incapable of placing sound
behind (and to the sides of, etc.) the listener is obvious. That to
accurately replicate an acoustic event requires sounds (a
potentiallysignificant portion of the total sound as previously discussed)
to be located behind the listener is equally obvious. The simple fact is
that a concert cannot be accurately reproduced with sounds emanating only
from in front of the listener. It's just not what we ever hear in the
original venue.

When viewed from this standpoint, even if DVD-A and SACD provide no more
"resolution" in two channels than standard red-book CDs, the potential for a
more accurate reproduction of the original musical event via a multi-channel
experience should have all audiophiles jumping at those formats. Rather
than quibbling over interconnects and speaker cables with all their limited
(if at all existing) possibilities for improvement, I suggest that a far
more meaningful upgrade would be the addition of 2 or 3 channels to existing
systems. Save for speaker upgrades, we really have maxed out the
capabilities of the stereo format. It is only through multi-channel
playback that we can hope to approach a true recreation of the "absolute
sound."

Bruce

  #2   Report Post  
Harry Lavo
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

"Bruce Abrams" wrote in message
...
As a choral singer, I regularly have the opportunity to hear what is
frequently referred to as the "absolute sound", namely unamplified music

in
a concert hall. As regards this reference, we audiophiles frequently
question whether the purpose of a reproduction system is to recreate the
original musical experience in the listening room, or whether it is to
reproduce what the recording engineer heard in the control room.

Recently during a rehearsal at Weil Recital Hall at Carnegie while waiting
to get on stage, I was sitting in the third row of the mostly empty hall
listening to a sonata for piano and cello and trying to figure out
(seemingly for the zillionth time) what it was that allows the ear to so
clearly distinguish even the finest quality reproduced music from the real
thing. While the obvious factors such as tonal balance and dynamic range
certainly contribute, I began to reconsider (again, for the zillionth

time)
the role that ambient sound plays. As I listened, it ocurred to me that

the
percentage of reflected sound to direct was probably much greater than I

had
previously thought (bearing in mind that while I was in row 3, the hall

was
mostly empty) and that the quality and quantity of reflected sound

probably
has as much to do with the subjective impression of "live or memorex" as
does the traditionally thought of factors of tonal balance and dynamic
range.

Back to the original question. I have always been of the opinion that an
accurate replay of the control room is all that could be hoped for, and

that
assuming the engineer did his job properly, a reasonable facsimile of the
original event could be had. (The thinking was based in part on the

concept
that no listening room could be made to acoustically duplicate a concert

or
recording venue. This also happens to be the thinking that led to

binaural
recording & playback techniques.) Which brings us to the possibility that
discreet multi-channel playback should be far more capable of reproducing
the original acoustic space than stereo ever could hope to. This is so
obvious and self-evident that I have difficulty understanding why the
audiophile community continues to disparage multi-channel systems as being
good for movies only. That stereo is physically incapable of placing

sound
behind (and to the sides of, etc.) the listener is obvious. That to
accurately replicate an acoustic event requires sounds (a
potentiallysignificant portion of the total sound as previously discussed)
to be located behind the listener is equally obvious. The simple fact is
that a concert cannot be accurately reproduced with sounds emanating only
from in front of the listener. It's just not what we ever hear in the
original venue.

When viewed from this standpoint, even if DVD-A and SACD provide no more
"resolution" in two channels than standard red-book CDs, the potential for

a
more accurate reproduction of the original musical event via a

multi-channel
experience should have all audiophiles jumping at those formats. Rather
than quibbling over interconnects and speaker cables with all their

limited
(if at all existing) possibilities for improvement, I suggest that a far
more meaningful upgrade would be the addition of 2 or 3 channels to

existing
systems. Save for speaker upgrades, we really have maxed out the
capabilities of the stereo format. It is only through multi-channel
playback that we can hope to approach a true recreation of the "absolute
sound."

Bruce


Bruce, I agree with you completely on this. Five channel sound, while not
ideal, moves us a long ways to that concert hall experience (I was listening
to E Power Biggs playing Bach in five channels last night, and even as
background music it was much more "real"). Certain symphonic works, and
even solo piano (Pollini's Chopin Polonaises on DG) when recorded properly
transport you into a "you are there" listening environment, and the sound is
just much more natural. Small groups recorded properly achieve a "they are
here" dimensionality (in part due to ambience) that can be equally
enthralling.

At the recent AES, a perfect example was offered by Neumann, who
commissioned a recording (done by Mike Pappas) of the Basie Big Band
recorded live at the University of Minnesota. The recording equipment was a
Sony 48 channel DSD workstation with Cardas mike cables. It was reproduced
at AES from the DSD machine itself though Avalon monitors (and a
custom-built subwoofer) and BAT amplifiers, again all Cardas. The sound was
absolutely spectacular. I have heard this band live, and it was like them
playing for you twenty feed away (which is about where I sat when I heard
them live). No fancy surround gimmicks, just a good hall and a great band.
Incidentally, Mike said they measured the sound pressure at the front of the
band at 140db. There was no compression used. I'm hoping they get this one
out as an SACD demo.

The demo, btw, also demonstrated one of the drawbacks of surround
sound...they could only seat 9 at a time in the room (about 20 x 15' I would
guess) and of these only the first six (3 x 3 seating) were really good.
The sweet spot is pretty small relative to all the real estate required for
speakers.

But back to Bruce's point, anybody holding out that two-channel is somehow
more "natural" is simply rationalizing. Multichannel is simply more
effective at reproducing music in a home listening environment.
  #4   Report Post  
ludovic mirabel
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

I have a long-standing interest. I've been playing with multichannel
sound for decades, ever since Hafler first proposed his version.
The first time I really heard what ambience can do was when Yamaha
produced a "Digital Sound Processor" ,which allowed a choice of
various digitally recreated ambiences: several concert halls, cinemas
etc. Playing with it I realised that the main problem of many
unlistenable recordings was not with faulty microphoning, distortion,
peaks and dips in frequency range and so on but primarily with the
place where they were recorded. This I suspect accounts for instance
for some of the more horrid DG. recordings of Berliner Philharmoniker.
And a lot of it could be corrected by adding better ambience.
I eventually replaced the Yamaha with JVC DSP 1000 that had some areas
of superiority -to my ears- mainly because it does not add its own
sound..
It has the choice of 20 different concert halls etc, controls for
the listening room size and reverberation, controls for the surround's
early and late reverberations, (amount of and duration separately),
duration of echo, high frequency stepped cut-off. A long learning
curve and the danger of exceess fiddling interfering with musical
experience always present)
Lately it required a repair when I found out that no more similar
units are being made by anyone. Lexicon has some features but not the
variety of choice and controls. I have no personal experience with 5.1
sound but in principle it is limited compared to the six speaker
surround of JVC.
I use the Lexicon speaker setup- the two side speakers right by
the sides of my listening seat rather than further up front. If used
discreetly they (to me) merge perfectly

At present I find symphonic, organ and pop music infinitely
pleasanter to listen with surround. So do my male friends. In fact I
get panicky when I think that my Yamaha DSP could one day expire
irreparabely.
Many solo piano and voice recordings can also stand some fiddling
with surround.
But a note of caution. A frequent visitor, a woman
professional pianist dislikes any surround. My wife too protests
against any slight indiscretio in its use. Women DO hear things that
men miss. How many women hi-fi fans does anyone know? Perhaps they
know better the imitation from the real than we do and do not value
the attempts at closing the gap.
Ludovic Mirabel

"Harry Lavo" wrote in message ...
"Bruce Abrams" wrote in message
...
As a choral singer, I regularly have the opportunity to hear what is
frequently referred to as the "absolute sound", namely unamplified music

in
a concert hall. As regards this reference, we audiophiles frequently
question whether the purpose of a reproduction system is to recreate the
original musical experience in the listening room, or whether it is to
reproduce what the recording engineer heard in the control room.

Recently during a rehearsal at Weil Recital Hall at Carnegie while waiting
to get on stage, I was sitting in the third row of the mostly empty hall
listening to a sonata for piano and cello and trying to figure out
(seemingly for the zillionth time) what it was that allows the ear to so
clearly distinguish even the finest quality reproduced music from the real
thing. While the obvious factors such as tonal balance and dynamic range
certainly contribute, I began to reconsider (again, for the zillionth

time)
the role that ambient sound plays. As I listened, it ocurred to me that

the
percentage of reflected sound to direct was probably much greater than I

had
previously thought (bearing in mind that while I was in row 3, the hall

was
mostly empty) and that the quality and quantity of reflected sound

probably
has as much to do with the subjective impression of "live or memorex" as
does the traditionally thought of factors of tonal balance and dynamic
range.

Back to the original question. I have always been of the opinion that an
accurate replay of the control room is all that could be hoped for, and

that
assuming the engineer did his job properly, a reasonable facsimile of the
original event could be had. (The thinking was based in part on the

concept
that no listening room could be made to acoustically duplicate a concert

or
recording venue. This also happens to be the thinking that led to

binaural
recording & playback techniques.) Which brings us to the possibility that
discreet multi-channel playback should be far more capable of reproducing
the original acoustic space than stereo ever could hope to. This is so
obvious and self-evident that I have difficulty understanding why the
audiophile community continues to disparage multi-channel systems as being
good for movies only. That stereo is physically incapable of placing

sound
behind (and to the sides of, etc.) the listener is obvious. That to
accurately replicate an acoustic event requires sounds (a
potentiallysignificant portion of the total sound as previously discussed)
to be located behind the listener is equally obvious. The simple fact is
that a concert cannot be accurately reproduced with sounds emanating only
from in front of the listener. It's just not what we ever hear in the
original venue.

When viewed from this standpoint, even if DVD-A and SACD provide no more
"resolution" in two channels than standard red-book CDs, the potential for

a
more accurate reproduction of the original musical event via a

multi-channel
experience should have all audiophiles jumping at those formats. Rather
than quibbling over interconnects and speaker cables with all their

limited
(if at all existing) possibilities for improvement, I suggest that a far
more meaningful upgrade would be the addition of 2 or 3 channels to

existing
systems. Save for speaker upgrades, we really have maxed out the
capabilities of the stereo format. It is only through multi-channel
playback that we can hope to approach a true recreation of the "absolute
sound."

Bruce


Bruce, I agree with you completely on this. Five channel sound, while not
ideal, moves us a long ways to that concert hall experience (I was listening
to E Power Biggs playing Bach in five channels last night, and even as
background music it was much more "real"). Certain symphonic works, and
even solo piano (Pollini's Chopin Polonaises on DG) when recorded properly
transport you into a "you are there" listening environment, and the sound is
just much more natural. Small groups recorded properly achieve a "they are
here" dimensionality (in part due to ambience) that can be equally
enthralling.

At the recent AES, a perfect example was offered by Neumann, who
commissioned a recording (done by Mike Pappas) of the Basie Big Band
recorded live at the University of Minnesota. The recording equipment was a
Sony 48 channel DSD workstation with Cardas mike cables. It was reproduced
at AES from the DSD machine itself though Avalon monitors (and a
custom-built subwoofer) and BAT amplifiers, again all Cardas. The sound was
absolutely spectacular. I have heard this band live, and it was like them
playing for you twenty feed away (which is about where I sat when I heard
them live). No fancy surround gimmicks, just a good hall and a great band.
Incidentally, Mike said they measured the sound pressure at the front of the
band at 140db. There was no compression used. I'm hoping they get this one
out as an SACD demo.

The demo, btw, also demonstrated one of the drawbacks of surround
sound...they could only seat 9 at a time in the room (about 20 x 15' I would
guess) and of these only the first six (3 x 3 seating) were really good.
The sweet spot is pretty small relative to all the real estate required for
speakers.

But back to Bruce's point, anybody holding out that two-channel is somehow
more "natural" is simply rationalizing. Multichannel is simply more
effective at reproducing music in a home listening environment.

  #5   Report Post  
Uptown Audio
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

I am curious as to how many ears you used when making this
"observation" and how they were arranged in relation to your head.
Stereo pictures can create incredibly deep and realistic spatial
detail as can stereo recordings. I would completely agree in principal
with you that, equipment quality aside, technique is everything. We
have had guests at our home watching movies and on several occasions
have witnessed them look around the room for the other speakers and
even behind them towards the street to see if someone was approaching
from outside as the depth of the sound was so real as to be
enveloping. We have only two speakers in the room.
- Bill
www.uptownaudio.com
Roanoke VA
(540) 343-1250

"Bruce Abrams" wrote in message
...
As a choral singer, I regularly have the opportunity to hear what is
frequently referred to as the "absolute sound", namely unamplified

music in
a concert hall. As regards this reference, we audiophiles

frequently
question whether the purpose of a reproduction system is to recreate

the
original musical experience in the listening room, or whether it is

to
reproduce what the recording engineer heard in the control room.

Recently during a rehearsal at Weil Recital Hall at Carnegie while

waiting
to get on stage, I was sitting in the third row of the mostly empty

hall
listening to a sonata for piano and cello and trying to figure out
(seemingly for the zillionth time) what it was that allows the ear

to so
clearly distinguish even the finest quality reproduced music from

the real
thing. While the obvious factors such as tonal balance and dynamic

range
certainly contribute, I began to reconsider (again, for the

zillionth time)
the role that ambient sound plays. As I listened, it ocurred to me

that the
percentage of reflected sound to direct was probably much greater

than I had
previously thought (bearing in mind that while I was in row 3, the

hall was
mostly empty) and that the quality and quantity of reflected sound

probably
has as much to do with the subjective impression of "live or

memorex" as
does the traditionally thought of factors of tonal balance and

dynamic
range.

Back to the original question. I have always been of the opinion

that an
accurate replay of the control room is all that could be hoped for,

and that
assuming the engineer did his job properly, a reasonable facsimile

of the
original event could be had. (The thinking was based in part on the

concept
that no listening room could be made to acoustically duplicate a

concert or
recording venue. This also happens to be the thinking that led to

binaural
recording & playback techniques.) Which brings us to the

possibility that
discreet multi-channel playback should be far more capable of

reproducing
the original acoustic space than stereo ever could hope to. This is

so
obvious and self-evident that I have difficulty understanding why

the
audiophile community continues to disparage multi-channel systems as

being
good for movies only. That stereo is physically incapable of

placing sound
behind (and to the sides of, etc.) the listener is obvious. That to
accurately replicate an acoustic event requires sounds (a
potentiallysignificant portion of the total sound as previously

discussed)
to be located behind the listener is equally obvious. The simple

fact is
that a concert cannot be accurately reproduced with sounds emanating

only
from in front of the listener. It's just not what we ever hear in

the
original venue.

When viewed from this standpoint, even if DVD-A and SACD provide no

more
"resolution" in two channels than standard red-book CDs, the

potential for a
more accurate reproduction of the original musical event via a

multi-channel
experience should have all audiophiles jumping at those formats.

Rather
than quibbling over interconnects and speaker cables with all their

limited
(if at all existing) possibilities for improvement, I suggest that a

far
more meaningful upgrade would be the addition of 2 or 3 channels to

existing
systems. Save for speaker upgrades, we really have maxed out the
capabilities of the stereo format. It is only through multi-channel
playback that we can hope to approach a true recreation of the

"absolute
sound."

Bruce




  #6   Report Post  
Kalman Rubinson
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

On 21 Oct 2003 01:48:09 GMT, "Uptown Audio"
wrote:

I am curious as to how many ears you used when making this
"observation" and how they were arranged in relation to your head.
Stereo pictures can create incredibly deep and realistic spatial
detail as can stereo recordings. I would completely agree in principal
with you that, equipment quality aside, technique is everything. We
have had guests at our home watching movies and on several occasions
have witnessed them look around the room for the other speakers and
even behind them towards the street to see if someone was approaching
from outside as the depth of the sound was so real as to be
enveloping. We have only two speakers in the room.


While I have no doubt that inexperienced listeners can think that they
are hearing sounds from behind them, there is no way that a 2 channel
source on a 2 channel system can reproduce real sounds from any
direction than the front. What comes from the rear and sides is the
sound of your room, not the original event. That may be enough for
you.

Kal
  #7   Report Post  
Bruce Abrams
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

"Uptown Audio" wrote in message
...
I am curious as to how many ears you used when making this
"observation" and how they were arranged in relation to your head.
Stereo pictures can create incredibly deep and realistic spatial
detail as can stereo recordings. I would completely agree in principal
with you that, equipment quality aside, technique is everything. We
have had guests at our home watching movies and on several occasions
have witnessed them look around the room for the other speakers and
even behind them towards the street to see if someone was approaching
from outside as the depth of the sound was so real as to be
enveloping. We have only two speakers in the room.
- Bill
www.uptownaudio.com
Roanoke VA
(540) 343-1250


Last I checked, I have the same two ears that all healthy adults hopefully
have. Being able to create an illusion of soundstage width and depth (I'll
leave height alone for this discussion) is something we have all experienced
in a stereo environment. The psychoacoustic mechanisms that allow such an
illusion are well known and various tricks such as Q-sound have been
employed to reasonably locate sounds laterally. Having said that, stereo is
physically incapable of reproducing the reflected sound that envelopes one
in a performance hall. You just can't reproduce sounds from behind you with
speakers in front of you. It's impossible. In order to surround the
listener with reflected sound, you must have either more than two channels,
or be listening to a closely miked recording in the original acoustic space.

It just occured to me that an old KLH (I think it was KLH, but perhaps AR or
Advent) experiment in the late '60s further bears out this point. The
experiment was to place a small acoustic group (I can't remember the makeup
of the group) on the stage of a hall alongside a pair of speakers. The
audience was blindfolded and asked to pick whether they were hearing the
music live or played back through the speakers, and were frequently unable
to correctly choose. KLH used this a proof of the realism and naturalness
of their speakers. Given that speakers of that era were hardly accurate, I
suspect that something else was at play, namely the reflected sound of the
hall. In this test, both the live music and the reproduced music were
subject to the same acoustic properties of the hall. Reflections, reverb
and decay would all have been identical regardless of whether the sound was
live or reproduced (saving any discrepancies due to the radiation pattern of
the speakers.) The effect of the acoustic space simply swamped any
inaccuracies in the speakers thus creating the impression that it was the
speakers that were responsible for the quality of playback.


"Bruce Abrams" wrote in message
...
As a choral singer, I regularly have the opportunity to hear what is
frequently referred to as the "absolute sound", namely unamplified

music in
a concert hall. As regards this reference, we audiophiles

frequently
question whether the purpose of a reproduction system is to recreate

the
original musical experience in the listening room, or whether it is

to
reproduce what the recording engineer heard in the control room.

Recently during a rehearsal at Weil Recital Hall at Carnegie while

waiting
to get on stage, I was sitting in the third row of the mostly empty

hall
listening to a sonata for piano and cello and trying to figure out
(seemingly for the zillionth time) what it was that allows the ear

to so
clearly distinguish even the finest quality reproduced music from

the real
thing. While the obvious factors such as tonal balance and dynamic

range
certainly contribute, I began to reconsider (again, for the

zillionth time)
the role that ambient sound plays. As I listened, it ocurred to me

that the
percentage of reflected sound to direct was probably much greater

than I had
previously thought (bearing in mind that while I was in row 3, the

hall was
mostly empty) and that the quality and quantity of reflected sound

probably
has as much to do with the subjective impression of "live or

memorex" as
does the traditionally thought of factors of tonal balance and

dynamic
range.

Back to the original question. I have always been of the opinion

that an
accurate replay of the control room is all that could be hoped for,

and that
assuming the engineer did his job properly, a reasonable facsimile

of the
original event could be had. (The thinking was based in part on the

concept
that no listening room could be made to acoustically duplicate a

concert or
recording venue. This also happens to be the thinking that led to

binaural
recording & playback techniques.) Which brings us to the

possibility that
discreet multi-channel playback should be far more capable of

reproducing
the original acoustic space than stereo ever could hope to. This is

so
obvious and self-evident that I have difficulty understanding why

the
audiophile community continues to disparage multi-channel systems as

being
good for movies only. That stereo is physically incapable of

placing sound
behind (and to the sides of, etc.) the listener is obvious. That to
accurately replicate an acoustic event requires sounds (a
potentiallysignificant portion of the total sound as previously

discussed)
to be located behind the listener is equally obvious. The simple

fact is
that a concert cannot be accurately reproduced with sounds emanating

only
from in front of the listener. It's just not what we ever hear in

the
original venue.

When viewed from this standpoint, even if DVD-A and SACD provide no

more
"resolution" in two channels than standard red-book CDs, the

potential for a
more accurate reproduction of the original musical event via a

multi-channel
experience should have all audiophiles jumping at those formats.

Rather
than quibbling over interconnects and speaker cables with all their

limited
(if at all existing) possibilities for improvement, I suggest that a

far
more meaningful upgrade would be the addition of 2 or 3 channels to

existing
systems. Save for speaker upgrades, we really have maxed out the
capabilities of the stereo format. It is only through multi-channel
playback that we can hope to approach a true recreation of the

"absolute
sound."

Bruce


  #8   Report Post  
Steven Sullivan
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

Uptown Audio wrote:
I am curious as to how many ears you used when making this
"observation" and how they were arranged in relation to your head.


If by this you are resurrecting the 'we only have two ears so
we only need two speakers' argumetn, are you aware that the
first recommendations for optimal 'stereo' reproduction,
by the inventors of the format, involved using *three* front channels?

--
-S.

  #9   Report Post  
Steven Sullivan
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

Kalman Rubinson wrote:
On 21 Oct 2003 01:48:09 GMT, "Uptown Audio"
wrote:


I am curious as to how many ears you used when making this
"observation" and how they were arranged in relation to your head.
Stereo pictures can create incredibly deep and realistic spatial
detail as can stereo recordings. I would completely agree in principal
with you that, equipment quality aside, technique is everything. We
have had guests at our home watching movies and on several occasions
have witnessed them look around the room for the other speakers and
even behind them towards the street to see if someone was approaching
from outside as the depth of the sound was so real as to be
enveloping. We have only two speakers in the room.


While I have no doubt that inexperienced listeners can think that they
are hearing sounds from behind them, there is no way that a 2 channel
source on a 2 channel system can reproduce real sounds from any
direction than the front. What comes from the rear and sides is the
sound of your room, not the original event. That may be enough for
you.



The closest I have come to experiencing what UA describes , is when
playing some stereo Pink Floyd and Roger Waters recordings that used
something called 'holophonic sound' -- and there, things did not
sound like they were coming from behind me, but well off to the side.


--
-S.

  #10   Report Post  
All Ears
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

"Bruce Abrams" wrote in message
...
snip

You just can't reproduce sounds from behind you with
speakers in front of you. It's impossible.


This is not entirely true, actually the ears works as a filter, so that
sounds comming from behind will have a dramatic drop in the 8 kHz area. This
means that if you cut the 8kHz area from a sound image, it will appear as
the sound is comming from behind.

KE



  #11   Report Post  
Bruce Abrams
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

"All Ears" wrote in message
...
"Bruce Abrams" wrote in message
...
snip

You just can't reproduce sounds from behind you with
speakers in front of you. It's impossible.


This is not entirely true, actually the ears works as a filter, so that
sounds comming from behind will have a dramatic drop in the 8 kHz area.

This
means that if you cut the 8kHz area from a sound image, it will appear as
the sound is comming from behind.


That's not true. Your logic is faulty. You just effectively said that
since the sky is blue, anything that is blue must be the sky. Just because
the ear filters 8 kHz, sounds from the front that are cut at 8 kHz will not
automatically be located to the rear. There are directional clues that will
be missing. You just can't make a sound produced in front of a listener
sound like it's coming from behind the listener.
  #12   Report Post  
chung
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

All Ears wrote:
"Bruce Abrams" wrote in message
...
snip

You just can't reproduce sounds from behind you with
speakers in front of you. It's impossible.


This is not entirely true, actually the ears works as a filter, so that
sounds comming from behind will have a dramatic drop in the 8 kHz area. This
means that if you cut the 8kHz area from a sound image, it will appear as
the sound is comming from behind.

KE


I don't think it's that simple. Let's say you play some bass notes on
speakers in front of you. There is no 8KHz in those bass notes. How can
the ear interpret those as coming from the behind?
  #13   Report Post  
Dennis Moore
 
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Yes you can.

Don't know how it works, but it can be done.

One very clear example is in the movie "Quigley
down under". When Quigley arrives at his new employer's
ranch he is asked to demonstrate his markmanship.
In stereo (even off of VHS) if you are dead centered
between your speakers, you hear very distinct echoes
each time he fires his rifle, clearly from behind you.
You don't get this if you move much off the centerline
between the speakers.

Have heard this on two high end systems, and one little
all in one type home system. Also have heard other similar
effects from time to time in movies. That one is just a
very clear one I remember.

It is well known that sound directly from the front hit both
ears at once and make direction hard to determine. Front,
top, behind being somewhat confused in this situation. What
makes this Quigley episode so firmly from the rear I cannot
say. But it does this for a few other people I know, not just
for me.

Dennis

"Bruce Abrams" wrote in message
...
"All Ears" wrote in message
...
"Bruce Abrams" wrote in message
...
snip

You just can't reproduce sounds from behind you with
speakers in front of you. It's impossible.


This is not entirely true, actually the ears works as a filter, so that
sounds comming from behind will have a dramatic drop in the 8 kHz area.

This
means that if you cut the 8kHz area from a sound image, it will appear

as
the sound is comming from behind.


That's not true. Your logic is faulty. You just effectively said that
since the sky is blue, anything that is blue must be the sky. Just

because
the ear filters 8 kHz, sounds from the front that are cut at 8 kHz will

not
automatically be located to the rear. There are directional clues that

will
be missing. You just can't make a sound produced in front of a listener
sound like it's coming from behind the listener.


  #14   Report Post  
Uptown Audio
 
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Actually, your argument is faulty. What he is saying is that the brain
expects and has learned that sounds that are located to the rear have
a decrease in frequency at around 8khz. Thus, when anything has such a
frequency anomiliy, it creates a sensation that things appear to be
heard as being behind you. That does not make them actually behind you
and does not necessitate that. I think that frequency and phase
relationships play a large part in sound localization and are used
creatively by those who produce artificial surround programs for use
with two channel systems regardless of the recording techniques. For
recordings that are very well done for stereo whether intentionally,
accidentally or coincidentally, the effects on the depth of soundstage
are appearant. As an example of how this can work, imagine a recording
of a race track, where the cars are going around you in a circle. This
is a stereo recording, whre the microphones are static as you are in
your listening position and the cars race in front, to your left, in
behind, and to your right before finally returning to the forward
position. The sound that is being recorded is the direct, in-phase
sound of the cars intially, then level rduced to your right, then
out-of-phase and level reduced or some frequencies thereof as the
sound being recorded when they are behind you is largely of the echo
from the objects in front of you like the wall and less of the actual
cars, then the sound becomes more normalized in the right side until
they appear in front of you once again. You can do this with six mic
locations and six speaker locations as well; it will just cost you
three times the amount. The trouble with recordings is that most are
not done in this manner and are subsequently mixed to further reduce
the effect of the live experience. Those that are well-done will
reveal such spacial cues and when played back on a system with
sufficient resolving capabilities will reveal them there as well. So
it is not really the speakers that need to be behind you, but the
brain that needs to be fed the proper signals to generate the feeling
as if the events were actually happening behind you, as in real life.
-Bill
www.uptownaudio.com
Roanoke VA
(540) 343-1250

"Bruce Abrams" wrote in message
...
"All Ears" wrote in message
...
"Bruce Abrams" wrote in message
...
snip

You just can't reproduce sounds from behind you with
speakers in front of you. It's impossible.


This is not entirely true, actually the ears works as a filter, so

that
sounds comming from behind will have a dramatic drop in the 8 kHz

area.
This
means that if you cut the 8kHz area from a sound image, it will

appear as
the sound is comming from behind.


That's not true. Your logic is faulty. You just effectively said

that
since the sky is blue, anything that is blue must be the sky. Just

because
the ear filters 8 kHz, sounds from the front that are cut at 8 kHz

will not
automatically be located to the rear. There are directional clues

that will
be missing. You just can't make a sound produced in front of a

listener
sound like it's coming from behind the listener.


  #15   Report Post  
Midlant
 
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Default Hi-fi, High-end and Multi-channel reproduction

Some years back while living in a big ranch style house in San Diego I
was fortunate enough to have a largish rectangular living room (not by
todays standards though). Equipment was simple enough, Polk RTA-12C's
hooked to a Kenwood amp and preamp and a Fisher CD player (which I truly
loved and still can't find a cd player to this day that is able to
create such a warm and smooth sound as that cheap $149, 1986 cd player
did). On a live recording of Def Leopard on CD, one of the tracks
featured a guitar solo. The sound of that guitar emanated from behind
and above me so that it was coming from where the wall met the ceiling.
I enjoyed having people over and popping that CD in, as everyone would
sit up, turn around and look for a speaker behind them. It was
startling. You could pinpoint the spot it came from but, it was only
that portion of the song featuring the guitar solo. No other portion of
that song, or any other song on that CD or any other CD or vinyl record
could duplicate that experience. It was really amazing.
On my present system I get thrown for a loop as it seems so real when
sounds come from other than the speakers when the stereo is playing the
soundtrack/dialog during a video and I'm only using 2-channel.
Room interface? Yes. Life-like imaging? Yes. Room interface the reason
for the life-like imaging? Probably.

John



  #16   Report Post  
Uptown Audio
 
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It can actually be experienced in rather "dead" rooms with good
recordings on good equipment. My room does not really fit the "dead"
description, but it is neutral having plaster walls and wall-to-wall
carpet plus a very cushy couch and a lot of coverings and furnishings
to break-up any reflections. I believe that phase relationships in a
recording contain much of this spatial information. I am sure that you
have a few miles on your ears as well, but I am comfortable with my
own experiences and do not feel that I need you to justify or approve
of them to make them more real. We have both very high resolution
stereo and surround systems to listen to and I hear distinctly
different presentaions of sound field depth from each. That may or may
not be enough for you.
- Bill
www.uptownaudio.com
Roanoke VA
(540) 343-1250

"Kalman Rubinson" wrote in message
...
On 21 Oct 2003 01:48:09 GMT, "Uptown Audio"
wrote:

I am curious as to how many ears you used when making this
"observation" and how they were arranged in relation to your head.
Stereo pictures can create incredibly deep and realistic spatial
detail as can stereo recordings. I would completely agree in

principal
with you that, equipment quality aside, technique is everything. We
have had guests at our home watching movies and on several

occasions
have witnessed them look around the room for the other speakers and
even behind them towards the street to see if someone was

approaching
from outside as the depth of the sound was so real as to be
enveloping. We have only two speakers in the room.


While I have no doubt that inexperienced listeners can think that

they
are hearing sounds from behind them, there is no way that a 2

channel
source on a 2 channel system can reproduce real sounds from any
direction than the front. What comes from the rear and sides is the
sound of your room, not the original event. That may be enough for
you.

Kal


  #17   Report Post  
Uptown Audio
 
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I have never been aware of that, rather of the facts. Please visit:
http://history.acusd.edu/gen/recording/stereo.html
http://www.headwize.com/articles/kvenn_art.htm
for just a couple of references to what has actually taken place.
Three channel recordings were an idea to create a greater dynamic
response and to fill-in any space that was not complete as a result of
recording technicalities or listening positions. Even still, there was
only one "optimum" position for listening as is still the case for any
playback system independent of the head. When coupled with video, even
the head-mounted systems must remain in proper orientation until we
develop eyes eleswhere...
- Bill
www.uptownaudio.com
Roanoke VA
(540) 343-1250

"Steven Sullivan" wrote in message
. net...
Uptown Audio wrote:
I am curious as to how many ears you used when making this
"observation" and how they were arranged in relation to your head.


If by this you are resurrecting the 'we only have two ears so
we only need two speakers' argumetn, are you aware that the
first recommendations for optimal 'stereo' reproduction,
by the inventors of the format, involved using *three* front

channels?

--
-S.


  #18   Report Post  
Kalman Rubinson
 
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On Wed, 22 Oct 2003 00:32:24 GMT, "Uptown Audio"
wrote:

Actually, your argument is faulty. What he is saying is that the brain
expects and has learned that sounds that are located to the rear have
a decrease in frequency at around 8khz. Thus, when anything has such a
frequency anomiliy, it creates a sensation that things appear to be
heard as being behind you.


As long as you have other cues to accompany that one. In the
interesting and detailed example that you give, phase and, most
important, expectation play important roles. Without the change of
direction and the change in phase and the experience of oval tracks,
the 8KHz cut is insufficient. That said, the frequency cut cannot, by
itself, cause one to hear the sound of a musical instrument or voice
behind you.

And further, while one can manipulate a number of parameters to
simulate rear/surround effects, the fact remains that normal,
well-produced stereo recordings do not convey any rear/surround
information that is not mixed irretrievably with the front signals.
Just listen to all the sound decay forward as an example.

Kal

  #20   Report Post  
Steven Sullivan
 
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Default Hi-fi, High-end and Multi-channel reproduction

Uptown Audio wrote:
I have never been aware of that, rather of the facts. Please visit:
http://history.acusd.edu/gen/recording/stereo.html
http://www.headwize.com/articles/kvenn_art.htm
for just a couple of references to what has actually taken place.
Three channel recordings were an idea to create a greater dynamic
response and to fill-in any space that was not complete as a result of
recording technicalities or listening positions.


Yup. Like I said, three channels were considered ideal.
see also:

http://www.dynaudioacoustics.com/Fil..._Sourround.pdf

from which I extract this quote (from p 4 of 16):

"While it was the general consensus that three channels was the ideal number
for optimum music playback, two-channel stereo became the standard mostly for
reasons of cost, convenience and commercial practicality in connection with
the introduction of the LP and FM Stereo."


Even still, there was
only one "optimum" position for listening as is still the case for any
playback system independent of the head. When coupled with video, even
the head-mounted systems must remain in proper orientation until we
develop eyes eleswhere...


And this makes stereo preferable to multichannel how? 'Audiophiles' surely
are used to the idea of there being one *best* sweet spot.






  #21   Report Post  
Stewart Pinkerton
 
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On 21 Oct 2003 20:18:37 GMT, Bruce Abrams
wrote:

"All Ears" wrote in message
...
"Bruce Abrams" wrote in message
...
snip

You just can't reproduce sounds from behind you with
speakers in front of you. It's impossible.


This is not entirely true, actually the ears works as a filter, so that
sounds comming from behind will have a dramatic drop in the 8 kHz area.

This
means that if you cut the 8kHz area from a sound image, it will appear as
the sound is comming from behind.


That's not true. Your logic is faulty. You just effectively said that
since the sky is blue, anything that is blue must be the sky. Just because
the ear filters 8 kHz, sounds from the front that are cut at 8 kHz will not
automatically be located to the rear. There are directional clues that will
be missing. You just can't make a sound produced in front of a listener
sound like it's coming from behind the listener.


That's not true. Your logic is faulty. There are no 'directional
clues' in a direct front to direct rear traverse that don't involve
manipulation of the HRTF. Indeed, aside from transients, we generally
have great difficulty in distinguishing a sound directly in front from
one directly behind, *unless* it has significant HF content. Those
designing warning sirens for emergency service vehicles are well aware
of this - as is anyone who has ever tried to find their mobile phone
when it rings!
--

Stewart Pinkerton | Music is Art - Audio is Engineering
  #22   Report Post  
Stewart Pinkerton
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

On 21 Oct 2003 19:33:00 GMT, "All Ears" wrote:

"Bruce Abrams" wrote in message
...
snip

You just can't reproduce sounds from behind you with
speakers in front of you. It's impossible.


This is not entirely true, actually the ears works as a filter, so that
sounds comming from behind will have a dramatic drop in the 8 kHz area. This
means that if you cut the 8kHz area from a sound image, it will appear as
the sound is comming from behind.


Indeed, I notice an *extremely* persuasive overhead front to back
movement of the sound image of USS Enterprise in Star Trek VI, which I
expect is a combination of phase and frequency manipulation. I use
only two speakers for TV sound.
--

Stewart Pinkerton | Music is Art - Audio is Engineering
  #23   Report Post  
Stewart Pinkerton
 
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On 21 Oct 2003 22:48:38 GMT, chung wrote:

All Ears wrote:
"Bruce Abrams" wrote in message
...
snip

You just can't reproduce sounds from behind you with
speakers in front of you. It's impossible.


This is not entirely true, actually the ears works as a filter, so that
sounds comming from behind will have a dramatic drop in the 8 kHz area. This
means that if you cut the 8kHz area from a sound image, it will appear as
the sound is comming from behind.

KE

I don't think it's that simple. Let's say you play some bass notes on
speakers in front of you. There is no 8KHz in those bass notes. How can
the ear interpret those as coming from the behind?


How can it interpret them as coming from *any* location? Ever tried to
decide which phone in a modern office is ringing?
--

Stewart Pinkerton | Music is Art - Audio is Engineering
  #24   Report Post  
 
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Default Hi-fi, High-end and Multi-channel reproduction

And further, while one can manipulate a number of parameters to
simulate rear/surround effects, the fact remains that normal,
well-produced stereo recordings do not convey any rear/surround
information that is not mixed irretrievably with the front signals.
Just listen to all the sound decay forward as an example.


And why would you expect the sound decay NOT to sound like it was
coming from forward? I've never heard an unamplified live concert
where anything sounded like it was coming from anywhere other than
right where the musicians are. Not even in a giant and very "live"
church, where the room ambiance was almost louder than the musicians -
it still sounded like everything was coming from right where they were
playing. So I don't understand why people would want systems where
the room ambiance comes from somewhere other than the front.
To me, if it ever sounded like it wasn't at the front, I would
consider it very unrealistic.

Do other people hear reverberations sounding as though they're
coming from the walls? If so, that would explain the interest in
multi-channel. To me, it just seems like inviting trouble for no
good reason.

Bob
  #25   Report Post  
Nousaine
 
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Default Hi-fi, High-end and Multi-channel reproduction

Steven Sullivan wrote:

Uptown Audio wrote:
I have never been aware of that, rather of the facts. Please visit:
http://history.acusd.edu/gen/recording/stereo.html
http://www.headwize.com/articles/kvenn_art.htm
for just a couple of references to what has actually taken place.
Three channel recordings were an idea to create a greater dynamic
response and to fill-in any space that was not complete as a result of
recording technicalities or listening positions.


Yup. Like I said, three channels were considered ideal.
see also:

http://www.dynaudioacoustics.com/Fil..._Sourround.pdf

from which I extract this quote (from p 4 of 16):

"While it was the general consensus that three channels was the ideal number
for optimum music playback, two-channel stereo became the standard mostly for

reasons of cost, convenience and commercial practicality in connection with
the introduction of the LP and FM Stereo."


Even still, there was
only one "optimum" position for listening as is still the case for any
playback system independent of the head. When coupled with video, even
the head-mounted systems must remain in proper orientation until we
develop eyes eleswhere...


And this makes stereo preferable to multichannel how? 'Audiophiles' surely
are used to the idea of there being one *best* sweet spot.


Actually the sweet spot argument is active again. One of the advantages of
multichannel for film sound is the ability to mix the soundtrack so that a
large part of the audience gets the intended sound.

A larger sweet listening area is one of the big advantages of surround in the
home and we get this with filmsound. However many engineers are often mixing
SACD, DTS and DVD-A releases in a one-listener sweet spot manner.

I hope they stop that. It interferes with the enjoyment of the sound when your
date has to sit in your lap for the whole performance.



  #26   Report Post  
chung
 
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Default Hi-fi, High-end and Multi-channel reproduction

Stewart Pinkerton wrote:
On 21 Oct 2003 22:48:38 GMT, chung wrote:

All Ears wrote:
"Bruce Abrams" wrote in message
...
snip

You just can't reproduce sounds from behind you with
speakers in front of you. It's impossible.

This is not entirely true, actually the ears works as a filter, so that
sounds comming from behind will have a dramatic drop in the 8 kHz area. This
means that if you cut the 8kHz area from a sound image, it will appear as
the sound is comming from behind.

KE

I don't think it's that simple. Let's say you play some bass notes on
speakers in front of you. There is no 8KHz in those bass notes. How can
the ear interpret those as coming from the behind?


How can it interpret them as coming from *any* location? Ever tried to
decide which phone in a modern office is ringing?


OK Stewart, I'll bite. How does one know if sound is from the back?

I have always thought that it is the difference in amplitude and phase
of the sounds arriving at the left and right ears that provide location
information. But obviously, if a sound is coming from behind you in the
middle, there may not be any difference in what each ear perceives.

On the other hand, I don't think it's as simple as a notch filter around
8 KHz. A telephone ringtone does not have much 8KHz component, yet
clearly I can tell if a phone is ringing behind me. When one of the many
phones rings, I think most of us will turn our heads to find a spot
where the sound is somewhat front-center of us, and then focus on the
ringing source. Well, most of the time at least. What if a 1KHz tone is
played. Can one tell if the tone comes from the back or front without
turning one's head?

  #27   Report Post  
Steven Sullivan
 
Posts: n/a
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wrote:
And further, while one can manipulate a number of parameters to
simulate rear/surround effects, the fact remains that normal,
well-produced stereo recordings do not convey any rear/surround
information that is not mixed irretrievably with the front signals.
Just listen to all the sound decay forward as an example.


And why would you expect the sound decay NOT to sound like it was
coming from forward? I've never heard an unamplified live concert
where anything sounded like it was coming from anywhere other than
right where the musicians are. Not even in a giant and very "live"
church, where the room ambiance was almost louder than the musicians -
it still sounded like everything was coming from right where they were
playing. So I don't understand why people would want systems where
the room ambiance comes from somewhere other than the front.
To me, if it ever sounded like it wasn't at the front, I would
consider it very unrealistic.


Because an average-sized listening room isn't going
to have anything like the ambience characteristics of a concert
hall?

Do other people hear reverberations sounding as though they're
coming from the walls? If so, that would explain the interest in
multi-channel. To me, it just seems like inviting trouble for no
good reason.


When I'm listening to surround sound wher ether surround carry only
ambience information, I don't 'hear' the reverb per se
and I certainly don't localize it as coming from 'behind' or from the
walls; I perceive an increased sense of 'largeness' to the presentation
coming from in front of me...whihc I suppose means the room 'sounds'
larger to me.



--
-S.

  #28   Report Post  
Bruce Abrams
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

wrote in message ...
And further, while one can manipulate a number of parameters to
simulate rear/surround effects, the fact remains that normal,
well-produced stereo recordings do not convey any rear/surround
information that is not mixed irretrievably with the front signals.
Just listen to all the sound decay forward as an example.


And why would you expect the sound decay NOT to sound like it was
coming from forward?


Because in a concert hall, sounds don't emanate solely from the stage.
Listen to the end of a tutti orchestral passage and then try to locate the
decay. You can't because it quite literally comes from all directions. You
might not perceive it as coming from anywhere, in fact, because it just
seems to be part of the room.

I've never heard an unamplified live concert
where anything sounded like it was coming from anywhere other than
right where the musicians are. Not even in a giant and very "live"
church, where the room ambiance was almost louder than the musicians -
it still sounded like everything was coming from right where they were
playing. So I don't understand why people would want systems where
the room ambiance comes from somewhere other than the front.
To me, if it ever sounded like it wasn't at the front, I would
consider it very unrealistic.

Do other people hear reverberations sounding as though they're
coming from the walls?


Absolutely. Not only from the walls, but from the ceiling, floor, in fact
from all surfaces in the hall.
  #29   Report Post  
Stewart Pinkerton
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

On Wed, 22 Oct 2003 18:24:15 GMT, chung wrote:

Stewart Pinkerton wrote:
On 21 Oct 2003 22:48:38 GMT, chung wrote:

All Ears wrote:
"Bruce Abrams" wrote in message
...
snip

You just can't reproduce sounds from behind you with
speakers in front of you. It's impossible.

This is not entirely true, actually the ears works as a filter, so that
sounds comming from behind will have a dramatic drop in the 8 kHz area. This
means that if you cut the 8kHz area from a sound image, it will appear as
the sound is comming from behind.

KE

I don't think it's that simple. Let's say you play some bass notes on
speakers in front of you. There is no 8KHz in those bass notes. How can
the ear interpret those as coming from the behind?


How can it interpret them as coming from *any* location? Ever tried to
decide which phone in a modern office is ringing?


OK Stewart, I'll bite. How does one know if sound is from the back?


One doesn't, unless one turns one's head. We often have difficulty in
locating sound directly behind us - until we turn our heads slightly.

I have always thought that it is the difference in amplitude and phase
of the sounds arriving at the left and right ears that provide location
information. But obviously, if a sound is coming from behind you in the
middle, there may not be any difference in what each ear perceives.


Quite so.

On the other hand, I don't think it's as simple as a notch filter around
8 KHz.


Not notch, low pass.

A telephone ringtone does not have much 8KHz component, yet
clearly I can tell if a phone is ringing behind me.


A mechanical bell tone most certainly does have significant HF
content, and such a ringtone is *much* easier to locate than modern
tone generator 'rings'. Do you really claim to be able to locate an
electronic ring, such as most mobile phones or office phones?

When one of the many
phones rings, I think most of us will turn our heads to find a spot
where the sound is somewhat front-center of us, and then focus on the
ringing source. Well, most of the time at least. What if a 1KHz tone is
played. Can one tell if the tone comes from the back or front without
turning one's head?


There is absolutely no way to locate a steady sinusoid, except by
walking around to follow amplitude variation. Try it sometime.
--

Stewart Pinkerton | Music is Art - Audio is Engineering
  #30   Report Post  
Dennis Moore
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

I have experienced a good example of what Stewart is
talking about here.

Where I work, there was a large all metal building about
35 x60 feet with 25 foot sloping ceilings. It held some electrical
and electronic equipment all around the periphery. There
were about 3 dozen microprocessor monitor panels with
each piece of equipment being monitored. When certain
conditions occurred, an alarm would sound from that panel.
It sounded like maybe 1khz, and a sine wave or close to it.


Well if an alarm sounded it was pretty much impossible in this
highly reflective open space to figure out where it was coming
from. The alarm was the tone only. So you had to start at
one end, pull up the alarm display screen, and work your way
through it until you came across the right one. A terrible
design. A light should also have blinked on the panel or
something. This is also highly disconcerting to move where
it seems to be coming from only to have it sound like some
place else when you get there. You simply couldn't
tract it down via the sound.

Dennis

"Stewart Pinkerton" wrote in message
...
On Wed, 22 Oct 2003 18:24:15 GMT, chung wrote:

Stewart Pinkerton wrote:
On 21 Oct 2003 22:48:38 GMT, chung wrote:

All Ears wrote:
"Bruce Abrams" wrote in message
...
snip

You just can't reproduce sounds from behind you with
speakers in front of you. It's impossible.

This is not entirely true, actually the ears works as a filter, so

that
sounds comming from behind will have a dramatic drop in the 8 kHz

area. This
means that if you cut the 8kHz area from a sound image, it will

appear as
the sound is comming from behind.

KE

I don't think it's that simple. Let's say you play some bass notes on
speakers in front of you. There is no 8KHz in those bass notes. How can
the ear interpret those as coming from the behind?

How can it interpret them as coming from *any* location? Ever tried to
decide which phone in a modern office is ringing?


OK Stewart, I'll bite. How does one know if sound is from the back?


One doesn't, unless one turns one's head. We often have difficulty in
locating sound directly behind us - until we turn our heads slightly.

I have always thought that it is the difference in amplitude and phase
of the sounds arriving at the left and right ears that provide location
information. But obviously, if a sound is coming from behind you in the
middle, there may not be any difference in what each ear perceives.


Quite so.

On the other hand, I don't think it's as simple as a notch filter around
8 KHz.


Not notch, low pass.

A telephone ringtone does not have much 8KHz component, yet
clearly I can tell if a phone is ringing behind me.


A mechanical bell tone most certainly does have significant HF
content, and such a ringtone is *much* easier to locate than modern
tone generator 'rings'. Do you really claim to be able to locate an
electronic ring, such as most mobile phones or office phones?

When one of the many
phones rings, I think most of us will turn our heads to find a spot
where the sound is somewhat front-center of us, and then focus on the
ringing source. Well, most of the time at least. What if a 1KHz tone is
played. Can one tell if the tone comes from the back or front without
turning one's head?


There is absolutely no way to locate a steady sinusoid, except by
walking around to follow amplitude variation. Try it sometime.
--

Stewart Pinkerton | Music is Art - Audio is Engineering



  #31   Report Post  
Bruce Abrams
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

"Stewart Pinkerton" wrote in message
...
*snip*
OK Stewart, I'll bite. How does one know if sound is from the back?


One doesn't, unless one turns one's head. We often have difficulty in
locating sound directly behind us - until we turn our heads slightly.


This comment actually helps makes the case for multi-channel. Unless you
sit at a live event wearing a head clamp, your ears' positions relative to
both direct and indirect sound is constantly changing. Moving around,
changing your position, looking around the hall, etc. The reality of the
source of ambient sound is thus the reality. You hear the ambience from all
directions, because it really is coming from all directions, and while your
head position changes, the source of the sound is constant and thus you have
audible confirmation that you are moving your head. (This is one of the
reasons that headphone listening, even with an AirHead processor, is
somewhat unrealistic. While your head moves around, you have no audible
sense that your are.)

The only way of coming close to this in a listening room is with multiple
channels. The only question, is how many channels are required and how
should they be arrayed. Thinking out loud, here's one possibility. It's
been well established for nearly 50 years, that two channels is sufficient
to provide the illusion of a continuous lateral soundstage. This is the
basis of stereo. If two channels can accomplish this laterally at the
front, it seems reasonable that two channels should be able to create the
same illusion for both the rear and sides of an enveloping sound field. In
other words, two rear channels should be able to do no worse of a job
reproducing the rear ambience of a hall, than the front two channels do of
producing the front. Likewise with the side reflections. In such a
scenario (ie 4 discreetly recorded & played back channels), the front
speakers work together for the front image, the rear speakers provide the
rear, the left speakers (front & rear) provide the left side, and the right
speakers (front & rear) provide the right side. The problem with such a
setup would be a relatively limited sweet spot, as you would be limited
longitudinally (for the front-rear speaker combinations) in much the same
way as stereo is limited laterally. One way to minimize the sweet spot
problem might be the addition of one extra side channel on each side. This
would have a similar effect as the addition of a third channel to stereo.
(Never having experienced discreet 3 channel playback, I don't know how the
sweet spot is compared with 2 channel, but I suspect it is larger.)

So, while 4 channels would seem to provide adequate coverage of the entire
horizontal sound field albeit with a rather limited sweet spot, perhaps the
addition of 4 center channels (front, sides & rear) minimizes this
limitation.

Any comments? Just thinking out loud.

  #32   Report Post  
Dennis Moore
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

Recall JJ or someone saying research into how many channels
was enough had been done. And the minimum was 7 equally
spaced. I guess 8 would give you the result you need.
Obviously the marketing of 5.1 is simply that more is better.
If it were done in relation to what could give you truly
continuous and lifelike surround sound, then they would be
pushing 7 or 8 channels. Which they of course will once
5 is firmly established. Anybody think 16 might be better
still?

Dennis

"Bruce Abrams" wrote in message
news:eHimb.20136$e01.38611@attbi_s02...
"Stewart Pinkerton" wrote in message
...
*snip*
OK Stewart, I'll bite. How does one know if sound is from the back?


One doesn't, unless one turns one's head. We often have difficulty in
locating sound directly behind us - until we turn our heads slightly.


This comment actually helps makes the case for multi-channel. Unless you
sit at a live event wearing a head clamp, your ears' positions relative

to
both direct and indirect sound is constantly changing. Moving around,
changing your position, looking around the hall, etc. The reality of the
source of ambient sound is thus the reality. You hear the ambience from

all
directions, because it really is coming from all directions, and while

your
head position changes, the source of the sound is constant and thus you

have
audible confirmation that you are moving your head. (This is one of the
reasons that headphone listening, even with an AirHead processor, is
somewhat unrealistic. While your head moves around, you have no audible
sense that your are.)

The only way of coming close to this in a listening room is with multiple
channels. The only question, is how many channels are required and how
should they be arrayed. Thinking out loud, here's one possibility. It's
been well established for nearly 50 years, that two channels is sufficient
to provide the illusion of a continuous lateral soundstage. This is the
basis of stereo. If two channels can accomplish this laterally at the
front, it seems reasonable that two channels should be able to create the
same illusion for both the rear and sides of an enveloping sound field.

In
other words, two rear channels should be able to do no worse of a job
reproducing the rear ambience of a hall, than the front two channels do of
producing the front. Likewise with the side reflections. In such a
scenario (ie 4 discreetly recorded & played back channels), the front
speakers work together for the front image, the rear speakers provide the
rear, the left speakers (front & rear) provide the left side, and the

right
speakers (front & rear) provide the right side. The problem with such a
setup would be a relatively limited sweet spot, as you would be limited
longitudinally (for the front-rear speaker combinations) in much the same
way as stereo is limited laterally. One way to minimize the sweet spot
problem might be the addition of one extra side channel on each side.

This
would have a similar effect as the addition of a third channel to stereo.
(Never having experienced discreet 3 channel playback, I don't know how

the
sweet spot is compared with 2 channel, but I suspect it is larger.)

So, while 4 channels would seem to provide adequate coverage of the entire
horizontal sound field albeit with a rather limited sweet spot, perhaps

the
addition of 4 center channels (front, sides & rear) minimizes this
limitation.

Any comments? Just thinking out loud.


  #33   Report Post  
Steven Sullivan
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

Dennis Moore wrote:
Recall JJ or someone saying research into how many channels
was enough had been done. And the minimum was 7 equally
spaced. I guess 8 would give you the result you need.
Obviously the marketing of 5.1 is simply that more is better.
If it were done in relation to what could give you truly
continuous and lifelike surround sound, then they would be
pushing 7 or 8 channels.


6.1 and 7.1 are indeed becoming increasingly available on A/C
receivers.

Which they of course will once
5 is firmly established. Anybody think 16 might be better
still?


I believe 10 (or 12?) channel setups to have their advocates.


--


-S.

  #34   Report Post  
Richard
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

"Uptown Audio" wrote:

I am curious as to how many ears you used when making this
"observation" and how they were arranged in relation to your head.
Stereo pictures can create incredibly deep and realistic spatial
detail as can stereo recordings. I would completely agree in principal
with you that, equipment quality aside, technique is everything. We
have had guests at our home watching movies and on several occasions
have witnessed them look around the room for the other speakers and
even behind them towards the street to see if someone was approaching
from outside as the depth of the sound was so real as to be
enveloping. We have only two speakers in the room.
- Bill
www.uptownaudio.com
Roanoke VA
(540) 343-1250


I suspect many, if not most of us have given this at least some
thought. As to your question about how many ears one has to hear
sound, a better question might be how many channels of sound does it
take to re-create a TRUE live sounding recording. I.e., our ears can
hear sound coming from all around us but a two speaker stereo system,
while VERY good, is unable to do this.
I have experimented with stereo (3D) photos using a process called
anaglyph. This, much like stereo audio, combines two pictures taken
from a slightly different angle and you use a pair of Red/Blue or
Red/Green 3-D glasses to combine these pictures. The result is that
you do get a somewhat more realistic photo because of the added depth
and it increases the "fun" factor. However, no one would be fooled
into thinking this pictures were real. A hologram would provide a
MUCH more realistic image but requires more than a stereo pair. This
is much the same in audio. We only have two ears and two eyes but we
are able to perceive MUCH more than stereo can provide. NOTE: I am
NOT knocking stereo in any way. Stereo production done well is
extremely satisfying. But multi channel done well is even better.
Unfortunately, many in the recording industry believe we want the
instruments in musical performances spread all around us instead of
using multiple channels to create a true holographic concert
experience.


Richard
  #35   Report Post  
Kalman Rubinson
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

On 25 Oct 2003 02:53:11 GMT, "Dennis Moore"
wrote:

Recall JJ or someone saying research into how many channels
was enough had been done. And the minimum was 7 equally
spaced. I guess 8 would give you the result you need.


One reason we need more is that we humans do not locate a phantom
lateral source (created by a front and rear transducer on the same
side) as well as we locate a phantom center source (created from L and
R transducers).

Kal



  #37   Report Post  
Harry Lavo
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

"Kalman Rubinson" wrote in message
news:YLEmb.21684$mZ5.82013@attbi_s54...
On 25 Oct 2003 02:53:11 GMT, "Dennis Moore"
wrote:

Recall JJ or someone saying research into how many channels
was enough had been done. And the minimum was 7 equally
spaced. I guess 8 would give you the result you need.


One reason we need more is that we humans do not locate a phantom
lateral source (created by a front and rear transducer on the same
side) as well as we locate a phantom center source (created from L and
R transducers).

Kal


I would guess this is partly why the ITU standard calls for the "surround"
speakers to be at 110 degrees...it puts them far enough "forward" that the
early can locate the directionality to some degree, versus further "back" in
the rear. However, from my experience living with it for a year now, I'd
have to say that it is barely adequate, and I can see where 7.1 with "side"
speakers as well as rears would be a pretty big plus. Of course, for pure
ambience it probably wouldn't make a huge difference, but in a pop surround
mix it certainly would. I'm not holding my breath, though, either for
fitting the equipment in a non-dedicated room and getting two additional
channels onto disk are both pretty big challenges. My guess is we are
stuck for better or worse withy 5.1 for most purposes, including our
surround music.

  #38   Report Post  
Uptown Audio
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

Giving that some thought; wouldn't it make sense then that sound
engineers seem to be lacking in the ability to create a true 3D sound
reproduction in that they are using too many source mikes and not a
pair (as in your ears) and letting the hall acoustic create it's own
3D effect (as in your analogy of multiple unlimited actually sources
of sound)? Would you then suggest that a concert could not be fully
enjoyed by a person with only two ears or that two acurate recording
devices would not best mimick that experience? What I am saying is
that regardless of how many points in space sound may eminate from, it
is perceived by only two receptors. Thus it can stand to reason that
it can be recorded in that fashion if the devices used are adequate
and can recover the proper spectrum from the same directions. Playback
would then require only two channels, yet would contain information
received directly and by reflection and frequency/phase relation from
the original hall in it's entirety. Once we get the recording done
properly, playback is definately the most difficult task as it
requires the power and scale to recreate the event without losing
those spacial cues to it's own distortions. Speaking of stereo
pictures, you should see the latest 3D film technology by Sensio for a
real attention grabber. It is flat-out fun. I believe that it uses two
cameras to record the scenes/movies and then it has a special digital
engine that combines them at a very fast rate which is practically
seamless, sort of like digital audio sampling in effect but not really
in principle. I did not really have time to read-up on how it is done,
but did get to see a cool demo film, which was better than any 3D
video that I have seen to date. Now the ultimate 3D sound transducer
must be in the form of a concave film that wraps completely around the
front, side, rear and over the tops and bottom edges (like a
planetarium, but with a flat roof and floor hey, walking in should
not be too challenging, eh?). Full frequency from any angle and
linear at all points and times. OK, that's sort of creeping me out
now...
- Bill
www.uptownaudio.com
Roanoke VA
(540) 343-1250

"Richard" wrote in message
...
"Uptown Audio" wrote:

I am curious as to how many ears you used when making this
"observation" and how they were arranged in relation to your head.
Stereo pictures can create incredibly deep and realistic spatial
detail as can stereo recordings. I would completely agree in

principal
with you that, equipment quality aside, technique is everything. We
have had guests at our home watching movies and on several

occasions
have witnessed them look around the room for the other speakers and
even behind them towards the street to see if someone was

approaching
from outside as the depth of the sound was so real as to be
enveloping. We have only two speakers in the room.
- Bill
www.uptownaudio.com
Roanoke VA
(540) 343-1250


I suspect many, if not most of us have given this at least some
thought. As to your question about how many ears one has to hear
sound, a better question might be how many channels of sound does it
take to re-create a TRUE live sounding recording. I.e., our ears

can
hear sound coming from all around us but a two speaker stereo

system,
while VERY good, is unable to do this.
I have experimented with stereo (3D) photos using a process called
anaglyph. This, much like stereo audio, combines two pictures taken
from a slightly different angle and you use a pair of Red/Blue or
Red/Green 3-D glasses to combine these pictures. The result is that
you do get a somewhat more realistic photo because of the added

depth
and it increases the "fun" factor. However, no one would be fooled
into thinking this pictures were real. A hologram would provide a
MUCH more realistic image but requires more than a stereo pair.

This
is much the same in audio. We only have two ears and two eyes but

we
are able to perceive MUCH more than stereo can provide. NOTE: I am
NOT knocking stereo in any way. Stereo production done well is
extremely satisfying. But multi channel done well is even better.
Unfortunately, many in the recording industry believe we want the
instruments in musical performances spread all around us instead of
using multiple channels to create a true holographic concert
experience.


Richard


  #39   Report Post  
Kalman Rubinson
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

On Wed, 29 Oct 2003 06:02:14 GMT, "Uptown Audio"
wrote:

Giving that some thought; wouldn't it make sense then that sound
engineers seem to be lacking in the ability to create a true 3D sound
reproduction in that they are using too many source mikes and not a
pair (as in your ears) and letting the hall acoustic create it's own
3D effect (as in your analogy of multiple unlimited actually sources
of sound)? Would you then suggest that a concert could not be fully
enjoyed by a person with only two ears or that two acurate recording
devices would not best mimick that experience? What I am saying is
that regardless of how many points in space sound may eminate from, it
is perceived by only two receptors.


This is an oversimplification. YOur two ears, including external,
middle and internal portions, plus your brain can interpret 3D sound
in the real world because they are getting 3D sound. You cannot
record 3D sound (not a good term but I quote it from you) with only
two receptor sets unless you add a brain (as does, to a degree, the
Soundfield Mike). Give the human system 2 sources and it cannot
interpret (accurately) what the 3D original was.

Kal

  #40   Report Post  
Bruce Abrams
 
Posts: n/a
Default Hi-fi, High-end and Multi-channel reproduction

"Kalman Rubinson" wrote in message
news:47Snb.57301$HS4.298229@attbi_s01...
This is an oversimplification. YOur two ears, including external,
middle and internal portions, plus your brain can interpret 3D sound
in the real world because they are getting 3D sound. You cannot
record 3D sound (not a good term but I quote it from you) with only
two receptor sets unless you add a brain (as does, to a degree, the
Soundfield Mike). Give the human system 2 sources and it cannot
interpret (accurately) what the 3D original was.


That's not entirely true. While the difficulties of true binaural recording
are myriad, when done properly for a specific listener, the results are
quite startling in their replication of the original event. Unfortunately,
the difficulties render the process impractical.

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