Loudspeaker Accuracy

[Dunlavy Audio Labs]

I have resisted replying to Gary Eichmeyer's recent postings, especially
those targeting John Ongtooguk, Coyote, "uh OH!", and others, until now.
But I believe the time has come to try and set the record straight by
stating well-known and well-understood facts attributable to competent
scientists, acoustical engineers, recording engineers and physicists.

However, it appears that Gary does not wish to be swayed by such facts,
preferring instead to trumpet his own incorrect ideas as though they
were "gospel". Anyway, lets once again explore why Gary's "teachings"
are not in consonance with teachings known and understood by those
well-versed in relevant fields.

For example, when an audiophile quality recording is made of a symphony
orchestra playing within a hall noted for its outstanding acoustical
properties, most experienced recording engineers attempt to capture (1)
the complex inner-detail of individual instruments, (2) an accurate
stereo rendition of the orchestra's soundstage, (3) acoustical
separation of different instruments, (4) the "ambiance" of the hall, and
(5) a "natural" spectral balance that takes into account the acoustical
properties of the venue. The "bottom-line" intent of a competent
recording engineer is to capture the "true acoustical presence" of the
orchestra's performance within that particular symphony hall so that
an audiophile with a suitably accurate system can hear the music much as
the engineer heard it while making the recording.

How do I know this? Very simple! I was a member of a team under the
supervision of the well-known Musicologist Dr. Robert Winter of UCLA
when he was in Colorado Springs to make an interactive CD of the
Colorado Springs Symphony playing the Appalachian Springs. He spent
weeks at our facility listening to the recordings in our well-equipped
listening room to determine what alterations to make in the recording
process, which mics better captured the essence of the music, which mic
locations yielded the most accurate soundstage, e.g., location of
individual instruments, separation of instruments, relative distances of
different instruments, etc.

Shortly after this project was completed, the Symphony's Board of
Directors asked me if I would record future monthly performances for
re-broadcast over KCME, a local classical FM station. I did so for the
next two and one-half symphony seasons. Making these recordings provided
a rare opportunity to experiment with mic types, mic placing, recording
equipment, etc. The most accurate of these recordings, in my opinion,
were those I made with a perfectly matched pair of
instrumentation-quality, omni-directional mics with ultra-low noise/low
distortion FET pre-amps. The recorder was a nearly flawless 24-bit DAT
machine. My favorite mic location was 10 feet above the "third row
center" seat, directly in front of the orchestra. At this location, the
first-row musicians were about 18-22 feet from the mics.

Monitoring the recordings in "real-time" through a pair of Sony MDR-7506
Professional Studio Monitor headphones, while seated directly below the
mics, there was literally no audible difference between the live music
and that heard through the phones =96 for at least the first few minutes
of listening. However, after several minutes of comparing the live with
the recorded music, very small differences became audible, mostly
consisting of being able to distinguish between sounds reflected from
the back of the concert hall Vs "direct arrival" sounds from the
orchestra. But the differences were very subtle and required several
minutes to discern.

Listening to these symphony recordings over measurably and audibly
accurate loudspeakers within our well-equipped listening room and
comparing the sound (in real-time) to that heard through the same Sony
MDR-7506 headphones, virtually all persons who have participated have
been unable to discern any audible difference for the first several
minutes. Thereafter, some of the more discerning listeners begin to pick
up on the same subtle differences heard while making the recording,
i.e., the inability of the headphones to provide a listener with audible
means for differentiating between sounds arriving from the "rear" of the
hall from the direct arrival sounds from the orchestra. Surprisingly,
however, the loudspeakers seem to restore some of the original concert hall
ambiance, perhaps by providing the pinna with an opportunity to
pre-process some front-back directivity cues introduced by reflections
from the rear wall directly behind the listener.

Carefully-controlled listening experiments, using a pair of
"side-firing" speakers located adjacent to the main loudspeakers to
introduce reflections of various amplitudes from the side walls of the
listening room, seemed to add additional "ambiance" to the reproduction.
However, our hearing processes appear to be very hard to fool and such
"time-delayed subsidiary radiation" has never been able to provide more
than momentary listening satisfaction. Usually, only a few minutes of
listening are necessary for a competent listener to reach the conclusion
that the perceived accuracy of the reproduction has been degraded.

The most important lesson we have learned, I believe, is that the most
subjectively-accurate reproduction of well-recorded music is obtained
with loudspeakers determined to be accurate based upon a complete set of
anechoic measurements (at a distance of about 10-12 feet) of all
measurable performance parameters, including time-domain,
frequency-domain, directivity, non-linear distortion, impedance, etc. We
have concluded, after much experimentation, that the most accurate
reproduction is obtained with loudspeakers possessing well-controlled
directivity patterns that minimize reflections from side walls, the wall
behind the loudspeakers, the floor and the ceiling surfaces. It is
important to reduce such reflections because they typically possess
delays amounting to only a few milliseconds =96 compared to the delays of
hundreds of milliseconds encountered within typical symphony halls, as
mentioned earlier.

So, technically speaking, how are the reflected sounds within a typical
home listening room heard and perceived differently from those heard
within a symphony hall? Well, although human hearing is not terribly
acute in discerning the arrival times of reflected sounds differing,
perhaps, by as much as tens of milliseconds, we are able to readily
discern the "spectral differences" created by the reflected sound
combining with the direct sound. For example, the frequency spectrum
created by the "vector addition" of the direct and reflected components
of a sound within a room consists of a series of peaks and partial nulls
that persist over a wide range of frequencies, with amplitudes dependent
upon the absorptive properties of the reflective surfaces. Amplitude peaks
occur at those frequencies where the direct and reflected sounds
arrive "in-phase" (multiples of one-wavelength). Likewise, nulls (or
partial nulls) occur at frequencies corresponding to those where the two
paths differ by an odd-multiple of half-wavelengths (180 degrees, 540
degrees, etc.).

Let's briefly examine the difference in the spectrum of peaks and nulls
that might occur within a typical home listening room versus the
spectrum that might be heard within a typical concert hall. For a
listener seated about 10 feet from a loudspeaker within a typical
listening room of modest size, the extra distance traveled by a
reflected wave, compared to the direct-arrival sound, probably averages
about 7 feet. This is equal to approximately one-half wavelength at
about 79 Hertz, the frequency at which the first "aural null" will be
heard by a listener (assuming the null is not partially "filled-in" by
in-phase reflections from other room surfaces). This null (or partial
null) will be repeated at each of several odd-harmonic frequencies,
e.g., 237 Hz, 395 Hz, 553 Hz, etc.

Likewise, "peaks" in response will be heard at frequencies where the
direct and reflected sound components "add in phase". In our example,
these will occur at approximately 157 Hz, 314 Hz, 471 Hz, etc.,
depending upon the dimensions, reflective properties and reflection
angles of the wall, ceiling and floor surfaces.

How do these typical listening room spectrums compare to those
encountered within a typical concert hall for a listener located,
perhaps, at a seat in third-row, center? Well, our own symphony hall in
Colorado Springs, would probably yield a first reflection arriving about
100 milliseconds after the direct arrival sound. This will create a
spectrum of "partial nulls" at frequencies corresponding to about 5.5
Hz, 17 Hz, 28 Hz, 39 Hz, 61 Hz, etc. Peaks in response will be heard
at frequencies of about 11 Hz, 22 Hz, 33 Hz, =85 121 Hz, 132 Hz, etc.
Acute listeners will perceive the spectrum comprised of such
closely-spaced peaks and nulls quite differently from the spectrum
produced by a pair of loudspeakers within a typical home listening room.

Indeed, it is these differences in the spectrum of "peaks and nulls"
that many blind persons utilize to determine the dimensions of a room
they are within and their approximate distance from walls, etc.

Now, lets return to audiophile systems and examine what loudspeaker
radiation patterns might reproduce well-recorded music with the greatest
perceived accuracy within a typical listening room. Assuming that one is
listening to music that has accurately captured the "ambiance" of the
recording venue, e.g., reflections from relevant reflective boundaries,
etc., will the much different spectrum of peaks and nulls created by
reflections from listening room surfaces add any relevant or realistic
ambiance to what is heard. No! At least, not when heard by competent,
experienced audiophiles. Why? Well, the significantly different spectrum
of peaks and nulls introduced by reflections within the listening room
will tend to obscure those within the recording being heard, resulting
in "blurred cues" as to the ambiance, etc. of the recording venue.

Thus, although an omni-directional loudspeaker (or one which accentuates
the level of sounds reflected from room boundaries) may sound
"expansive" and "encompassing" for a relatively short time, an
experienced audiophile will soon discover that such sound quality does
not coincide with the real-world "concert hall experience". This is
because our "ear-brain combo" is really a lot more perceptive and
smarter than many people believe. Thus, while it may take time for a
person to discover they have been "fooled" by a "cleaver loudspeaker
design", they will eventually reach that conclusion and will no longer
enjoy listening to such enhanced "make believe" reproduction.

The "bottom line" is simple: long-term, it is hard to beat the
reproduction provided by a stereo-pair of truly accurate loudspeakers
with "controlled-dispersion" radiation patterns that minimize the
undesirable spectral components created by wall, ceiling and floor
reflections. In consonance with this assertion, I am not aware of any
major recording or mastering studios that utilize loudspeakers with wide
vertical and/or horizontal directivity patterns. All of the ones with
which we are familiar and regularly speak to, use monitors with
directivity patterns optimized to minimize reflections from wall,
ceiling and floor surfaces. This permits them to monitor the sound of
their recordings in a manner that lets them judge how they will sound
and hopefully appeal to potential purchasers. Hmmm!

So! If listeners want to hear what the recording and mastering engineers
probably heard when making their recordings =96 why not use loudspeakers
with similar properties?

Best of listening,
John Dunlavy

[John Marks]

Dunlavy Audio Labs wrote:

LONG SNIP

> The "bottom line" is simple: long-term, it is hard to beat the
> reproduction provided by a stereo-pair of truly accurate loudspeakers
> with "controlled-dispersion" radiation patterns that minimize the
> undesirable spectral components created by wall, ceiling and floor
> reflections. In consonance with this assertion, I am not aware of any
> major recording or mastering studios that utilize loudspeakers with wide
> vertical and/or horizontal directivity patterns. All of the ones with
> which we are familiar and regularly speak to, use monitors with
> directivity patterns optimized to minimize reflections from wall,
> ceiling and floor surfaces. This permits them to monitor the sound of
> their recordings in a manner that lets them judge how they will sound
> and hopefully appeal to potential purchasers. Hmmm!
>
> So! If listeners want to hear what the recording and mastering engineers

> probably heard when making their recordings, why not use loudspeakers

> with similar properties?
>
> Best of listening,
> John Dunlavy

JOHN MARKS REPLIES:

Nearly every CD on the JMR label has been mastered by Bob Ludwig, either
at Masterdisk or Gateway. Bob has always used Duntech Sovereign 2001s;
at Gateway, in a room designed around them. So Mr. Dunlavy is
undoubtedly correct in stating that engineers, indeed 100% of those I am
familiar with, prefer speakers that have extremely limited dispersion.
The phrase "beams like a flashlight" comes to my mind.

JMR does not use studios for recording; we record location-live in
stereo or more recently, Bruck KFM 360 surround. On location, we do use
portable speakers of a type Mr. Dunlavy refers to, often Aerial 5s or
7s. ASA Monitor Pros are excellent also. Headphones are always
available also.

HOWEVER, for musical enjoyment in the home, I strongly prefer Richard
Shahinian's "polyradial" designs, above all the Diapasons. I find that
with careful attention to room voicing and the use of true-stereo
recordings, the Diapasons combine detail with body in a way I have
rarely heard in front-firing designs, and never for the same price
($8,500.00 per pair). Properly set up, the Diapasons can "focus down"
to a point source such as solo violin, or Glenn Gould's humming. The
Diapasons are not warmed-over Bose 901s. People who disparage them
usually have not heard them, or, if so, not heard them set up properly.
Even Richard's annual CES music-orgies, impresive as they are, are not
ideal conditions.

I do not use Diapasons for location monitoring for the same reason I
would not use Duntech 2001s (bulk), with the further proviso that the
recording shack arrangements are usually a cinderblock room in a
basement. Shahinian Diapasons would sound dreadful in Bob Ludwig's
room, because the far end is so extremely dead.

However, the contribution I (who am full of admiration for Mr. Dunlavy's
work) would like to make to this discussion is this: production is one
thing, enjoyment another. Specialized knives are used to filet salmon,
but that fact notwithstanding, I eat it with a fork.

Best regards,
--
John Marks
John Marks Records - Award-winning classical-music and jazz CDs
Please visit our website at http://www.jmrcds.com
e-mail: jmr...@jmrcds.com
phone (401) 782-6298 / toll-free phone (888) JMR-1919 / fax (401)
792-8375

[Eric Nelson]

If you plan on using a set of speakers so that a single
person will always sit in the same place to listen to
a recording, then narrow dispersion speakers (Dunlavy,
Hales, Thiel, Magnepan) work well. However, if you don't want
your soundstage to collapse as you walk out of the
very small sweet spot, get wide dispersion speakers
(Gallo, Merlin, VS, JM Lab). I prefer wide dispersion
speakers for most situations.

I also find that narrow dispersion speakers just plain
don't work very well for home theater.

--
Eric Nelson - sn...@nortel.ca (not Nortel spokesperson)
Parent Tennis Hack Audiophile Volvo 850 Driver Co-counsellor
Stock Market Investor Dog Owner Contact Dancer Technophile

[Gary Eickmeier/Susan Andrus]

Dunlavy Audio Labs wrote:
>
> I have resisted replying to Gary Eichmeyer's recent postings, especially
> those targeting John Ongtooguk, Coyote, "uh OH!", and others, until now.
> But I believe the time has come to try and set the record straight by
> stating well-known and well-understood facts attributable to competent
> scientists, acoustical engineers, recording engineers and physicists.
>
> However, it appears that Gary does not wish to be swayed by such facts,
> preferring instead to trumpet his own incorrect ideas as though they
> were "gospel". Anyway, lets once again explore why Gary's "teachings"
> are not in consonance with teachings known and understood by those
> well-versed in relevant fields.

I didn't realize that my posts could be characterized as "targeting."
We hopefully try to argue logically using point and counterpoint,
hoping to make an inroad somewhere in someone's thinking and advance
the hobby.

I don't know if I will be permitted to answer this, but what I would
like to say is that I object to Mr. Dunlavy just posting these
periodic diatribes, which seem to me like thinly disguised commercial
advocacy, without answering our individual posts as they come up. I
for one will not respond to him unless and until he interacts with the
rest of us, responding to our points as well.

Two times now I tried to respond to Dunlavy, and two times the
moderator told me it was better done as private E-mail and would not
let me respond. I think that as long as Mr. Dunlavy has singled me out
in his posting, which was approved, then I have a right to respond in
public.

I feel that Dunlavy's posts are an attempt to trash all of the points
I have made in this thread with a broad brush statement without
answering any of them. Then he takes us back to ground zero by simply
restating his philosophy of speaker design, daring us to respond to
him! I would request that the moderators turn down these diatribes as
commercial posts, unless he answers our points somewhere within
them. If this post is turned down, I will re-initiate it as a
meta-discussion.

What does everyone else think?

Gary Eickmeier

[Steve Zipser (Sunshine Stereo, Inc.)]

Gary Eickmeier/Susan Andrus wrote:

> I didn't realize that my posts could be characterized as "targeting."

Read them carefully, I think that is an apt description.

> We hopefully try to argue logically using point and counterpoint,
> hoping to make an inroad somewhere in someone's thinking and advance
> the hobby.
>
> I don't know if I will be permitted to answer this, but what I would
> like to say is that I object to Mr. Dunlavy just posting these
> periodic diatribes,

Because he disagrees with you, and because he blieves that you are
wrong, you call his post a diatribe!

> which seem to me like thinly disguised commercial
> advocacy, without answering our individual posts as they come up. I
> for one will not respond to him unless and until he interacts with the
> rest of us, responding to our points as well.

He has his opinions, founded in a wealth of science, physics,
engineering, AND experience in the RECORDING industry. He has a lot
to bring to the table, so I might ask what are your redentials, Gary?

> Two times now I tried to respond to Dunlavy, and two times the
> moderator told me it was better done as private E-mail and would not
> let me respond. I think that as long as Mr. Dunlavy has singled me out
> in his posting, which was approved, then I have a right to respond in
> public.

This is not true. John has argued with others publicly (yours truly
included, so why you feel singled out is a mystery. I frankly ma
surprised that the moderators posted you rejoinder.

> I feel that Dunlavy's posts are an attempt to trash all of the points
> I have made in this thread with a broad brush statement without
> answering any of them.

He did answer them, you just weren't listening. I also already
answered these points correctly.

> Then he takes us back to ground zero by simply
> restating his philosophy of speaker design, daring us to respond to
> him! I would request that the moderators turn down these diatribes as
> commercial posts, unless he answers our points somewhere within
> them. If this post is turned down, I will re-initiate it as a
> meta-discussion.
>
> What does everyone else think?

I think you are wrong. I think Dunlavy has every right to express
his opinions and his thoughts here - he sure knows more than most of
us. So what if he makes a product, just factor that into the
equation :-)

Cheers
Zip

--
Sunshine Stereo, Inc http://www.sunshinestereo.com
Tel: 305-757-9358 Fax: 305-757-1367
9535 Biscayne Blvd Miami Shores FL 33138
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Sunshine Stereo encourages all audiophiles to support their local
dealers. If you do not have a local dealer, we will gladly assist
you with all your audio and video needs! *** ENJOY THE MUSIC! ***

[Randall Bradley]

Headphone monitoring of "live" material is something that
I've had the opportunity to do on many occasions. There is
something very interesting going on with that. I have
observed that "direct" connection to the mics (not through
the tape, etc.) virtually always sounds substantially better
than does the same headphones on the recorded sound(s).

I've noticed this, almost without regard to the headphone
employed!

I suspect that there is more than one causal factor at play
here. But I speculate that the "unlimited" bandwidth may be
a major one.

It is surprising that what the mics hear from 10 feet above
the third row, corresponds spatially to what you hear aurally
from *any* seat in the house. Furthermore, that even if this
*did* in fact image similarly on *speakers* that it would
image so on *headphones* is all the more surprising to me.

Also, as mentioned before in similar threads, there *must* be
substantial leakage from the live sound through the headset,
making such a comparision somewhat moot, and the differences
obscured.

Try wearing headphones while your speakers are playing - same
thing.

This is not to say that excellent results were not acheived,
but that little has been proved or shown by this sort of
experiment - in terms of a theoretical comparison of these
processes. It does show how the art of recording requires
care, iteration, and experiment.

We the readers are generally not familliar with the hall in
Colorado Springs that Mr. Dunlavy refers to. I wonder, in
general terms, what sort of hall is it? Old, modern, or
contemporary. For example: Carnegie, Phillharmonic, Dallas -
respectively.

Most modern halls are rather dead. So the issues in recording
are entirely different than in Carnegie or the Troy Savings
Bank Music Hall up here - very live, maybe too live. Hmmmm....
with people or without?

Anyhow, I agree with John that the closer you can make a
speaker to technically "correct" (all the tests he mentioned)
the better chance that you will have a system that sounds
right. Or put another way, for the same drivers, the one that
is configured such that it tests best is very likely to
sound best too.

However, having said that, if we take our perfect omni (point
source) theoretical radiator and change the room from live
to anechoic, as we get closer to anechoic the % sound that is
*only* direct becomes very close to 100%. Similarly, in a
very live room (all concrete with ceramic tiles, ok??) the
"so-called" Controlled-Dispersion loudspeaker won't buy you
too much either. That rear wall is going to get you, *even*
if you fired "laser beams" of sound!

So, *much* depends upon your environement, as to the results
you will get. It is possible to treat your points of first HF
reflection to significantly absorb and diffuse, making the
listening situation quite acceptable with "wide dispersion"
speakers! Indeed, it can be argued that in this instance
those seated off center axis will have a superior stereo
image as compared to those seated off axis to the
"controlled-dispersion" loudspeaker in the "normal" room!!

Comparing to the "professional" recording environment is also
a big mistake. A majority of "professional" environments are
configured not on the basis of any great thought or
engineering concept, but as the result of what some other guy
did who was sucessful (commercially, of course!!), and he did
what he did because of the someone before him, etc., etc.
Going all the way back to Harry Olsen, and mono, which
started as radio stations. Yes, it is true that engineering
and testing is often applied, but that does not change the
basic underlying premises of recording studios and mastering
suites...

Furthermore, a vast majority of big studio monitors not only
sound horrible, but are super laser like at hf. So much so
that if you move a few inches one way or the other,
everything changes. This you can measure. Mostly, they want
them to go loud.

As a commercial manufacturer of speakers it would be
difficult to have to specify the room treatment along with
the sale. So, in the course of trying to make a "universally"
applicable and acceptable product, it makes sense to control
the dispersion with increasing frequency.

This also gives your product the best chance of sounding
"good" or "the same" in assorted showrooms and/or homes.

I would argue that while this approach may give the pro
repeatability, and *may* yield the "most accurate
reproduction" it does so ONLY on axis. Off axis, by
definition (the freq & power response varies with angle) it
clearly does NOT! For many average audiophiles there is a
need for excellent off axis results. Or good results sitting
down vs. standing up. That's not to imply that Dunlavy
speakers are not sufficiently dispersed so as to be
satisfactory in this regard.

But, if you say they are, then you are moving along the
SPECTRUM -from wide to narrrow, etc. SO, making a claim about
one philosphy's superiority needs to be significantly
tempered in light of the lack of absolutes.

IMHO

_-_-randy
BEAR Labs

PS. these thoughts are independent of the earlier threads,
and are not intended to support of disparage other postings.

[Randall Bradley]

Ummmm...

I don't know how to say this without gettting Mr. Marks
upset. BUT.

I believe that the two CDs that I received here for an
audition were both recent JMR releases. I checked the
area code and it matches what I remember - Rhode Island,
as the location for them. SO, I believe this to be correct.

I checked this against my Stereophile test CD and mono
recordings to be 100% sure my system was not at fault.

Both recordings were pressed with one channel 180 degrees
out of phase.

Even in phase, the presentation was not very much to my
liking. David Chesky has the art of minimalist micing
down. These two recordings were of that style, but did
not deliver the resolution or space.

It is not my aim to be critical of Mr. Marks, who I do not
know, and is likely a fine fellow.

However, It is instructive to point out that experts make
lots of mistakes, audio gurus don't always know everything,
and that I myself miss the boat on a regular basis. So,
just because some respected person has a preference it does
not make it good or right.

There are few absolutes in audio - thank goodness!!

_-_-randy
BEAR Labs

[Jim Cate]

In article <6n5ujr$6...@news01.aud.alcatel.com>,

"Steve Zipser (Sunshine Stereo, Inc.)" <z...@sunshinestereo.com> wrote:

>Gary Eickmeier/Susan Andrus wrote:

>> I don't know if I will be permitted to answer this, but what I would
>> like to say is that I object to Mr. Dunlavy just posting these
>> periodic diatribes,

>Because he disagrees with you, and because he blieves that you are
>wrong, you call his post a diatribe!

I tend to agree with Gary on this one. - John has a tendancy to
download a mass of technical information which is approximately
appropriate for the newsgroup discussion, but which doesn't
specifically address the question. - I think he owes us the courtesy
of reading the notes and addressing specifically the comments of the
note he is responding to.

>> which seem to me like thinly disguised commercial
>> advocacy, without answering our individual posts as they come up. I
>> for one will not respond to him unless and until he interacts with the
>> rest of us, responding to our points as well.

>He has his opinions, founded in a wealth of science, physics,
>engineering, AND experience in the RECORDING industry. He has a lot
>to bring to the table, so I might ask what are your redentials, Gary?

>> What does everyone else think?

>I think you are wrong. I think Dunlavy has every right to express
>his opinions and his thoughts here - he sure knows more than most of
>us. So what if he makes a product, just factor that into the
>equation :-)

____________________________________--

I do agree with Zip that John has lots of experience and know-how
in acoustics and in setting up and testing his speakers. I had the
opportunity of speaking with him at his CES room last January, and I
thought that he did an excellent job of setting up the SC-IV's and
some of his smaller speakers. - From his long experience, he chose
not to accept one of the smaller rooms at the Alexis, where most of
the demos were located, and instead selected a large, elongated room
in a hotel nearby. As far as I could tell, he was the only speaker
manufacturer with a demonstration room in that hotel. He had
obviously taken great care in arranging the speakers, positioning
them such that they faced across the long wall, as is his preference,
rather than down the length of the room. Additionally, though there
were several speakers in the room, Mr. Dunlavy positioned the SC-IVs
and the SC-IVA's near the listening area and facing the center of the
listening area, so that there was minimal interference from the other
speakers. I understand that the first step in his setup procedure is
to walk around the room clapping his hands in order to get a sense of
the acoustics. He was obviously showcasing his new SC-IVA's, and he
provided a level-matched switching loop which permitted the listener
to switch between the SC-IV's and the SC-IVA's. --

All this seems to be a good example of how experts in the field
with years of audio experience such as Mr. Dunlavy tend to "sweat the
small stuff" to enhance the total listening experience, and why
optimization of room acoustics still entails a combination of a
knowledge of the physics as well as experimentation with the
particular listening environment.

Jim Cate

[jj, curmudgeon and tiring philalethist]

In article <6n8c70$k...@news01.aud.alcatel.com>,

Jim Cate <Jim...@ix.netcom.com> wrote:
> All this seems to be a good example of how experts in the field
>with years of audio experience such as Mr. Dunlavy tend to "sweat the
>small stuff" to enhance the total listening experience, and why
>optimization of room acoustics still entails a combination of a
>knowledge of the physics as well as experimentation with the
>particular listening environment.

Well, in listening room setup, as in many other things, the
"devil is in the details".

If you want it to work out well, you do indeed sweat the small
stuff.

I wonder if John would like to comment on the propensity of places
like convention centers to have nearly square rooms that are almost
always something like 16x16x8.

Makes for INteresting listening.
--
Copyright j...@research.att.com 1998, all rights reserved, except transmission
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[Andre Yew]

ra...@poker.rdrc.rpi.edu (Randall Bradley) writes:

> Most modern halls are rather dead. So the issues in recording
> are entirely different than in Carnegie or the Troy Savings
> Bank Music Hall up here - very live, maybe too live. Hmmmm....
> with people or without?

Hi Randy, I don't think most modern halls are dead. For example, the
Dallas hall has an RT of 2.8 seconds, which is by far the longest of
the world's great halls. It also has two reverberation chambers
flanking it whose openings are covered by remote-controlled concrete
doors and can be varied to control the amount of reverberation in the
hall. There are a lot of crappy modern halls (like all the round
ones), but I wonder if there's also not some kind of Darwinian effect
going on where all the old bad halls are gone leaving us only with
the finest ones, and if we wait for 50 or 100 years, we'll see only
the good ones of our time survive.

> However, having said that, if we take our perfect omni (point
> source) theoretical radiator and change the room from live
> to anechoic, as we get closer to anechoic the % sound that is
> *only* direct becomes very close to 100%. Similarly, in a
> very live room (all concrete with ceramic tiles, ok??) the
> "so-called" Controlled-Dispersion loudspeaker won't buy you
> too much either. That rear wall is going to get you, *even*
> if you fired "laser beams" of sound!

I find it very difficult to talk about radiation patterns of speakers
without a soundfield-reproduction theory. Without such a theory,
there is no consistent way to rank or predict what patterns work, and
we end up with a cut-and-try method where there is no reproducible
result.

--Andre

--
PGP public key available

[John Ongtooguk]

Gary Eickmeier/Susan Andrus (imag...@gte.net) wrote:

: Dunlavy Audio Labs wrote:
: >
: > However, it appears that Gary does not wish to be swayed by such facts,

: > preferring instead to trumpet his own incorrect ideas as though they
: > were "gospel". Anyway, lets once again explore why Gary's "teachings"
: > are not in consonance with teachings known and understood by those
: > well-versed in relevant fields.

: I feel that Dunlavy's posts are an attempt to trash all of the points

: I have made in this thread with a broad brush statement without

: answering any of them. Then he takes us back to ground zero by simply

: restating his philosophy of speaker design, daring us to respond to
: him! I would request that the moderators turn down these diatribes as
: commercial posts, unless he answers our points somewhere within
: them. If this post is turned down, I will re-initiate it as a
: meta-discussion.

:
: What does everyone else think?

In the context of subjective criteria your 'points' are just as
valid as any others but otherwise Dunlavy is correct in noting
that you aren't swayed by facts, and that your ideas are incorrect.
Your paper on your 'new theory of stereo' was turned down for
publication by the AES almost ten years ago, you stated that their
critique showed a lack of understanding of the paper, and yet
you've apparently continued to cultivate these incorrect ideas all
these years, unswayed by any facts. Dunlavy like a few other
speaker designers appeals to linear systems theory, theory which
is well established in electronics, optics, communications,
3D hearing, architectural acoustics, etc., while you attempt to
bring a long discredited theory to the table. In defending your
theory you've also had the gall to note that Dunlavy hasn't done
anything more than any other dope with a soldering iron has
thought of.

I think as long as you're discussing your subjective preferences
there are no problems but you display symptoms of a classic crank
otherwise. It's not been a problem in this moderated newsgroup,
but I would consider it one if it ends up in chasing off one of
the few designers that post to this group.

John Ongtooguk (jo...@vcd.hp.com)

[Gary Eickmeier/Susan Andrus]

John Ongtooguk wrote:

> In the context of subjective criteria your 'points' are just as
> valid as any others but otherwise Dunlavy is correct in noting
> that you aren't swayed by facts, and that your ideas are incorrect.

I must ask you what facts you are talking about. And it is not
sufficient to say that my ideas are incorrect. He's got to answer them
somewhere, and say why.

> Your paper on your 'new theory of stereo' was turned down for
> publication by the AES almost ten years ago, you stated that their
> critique showed a lack of understanding of the paper, and yet
> you've apparently continued to cultivate these incorrect ideas all
> these years, unswayed by any facts. Dunlavy like a few other
> speaker designers appeals to linear systems theory, theory which
> is well established in electronics, optics, communications,
> 3D hearing, architectural acoustics, etc., while you attempt to
> bring a long discredited theory to the table. In defending your
> theory you've also had the gall to note that Dunlavy hasn't done
> anything more than any other dope with a soldering iron has
> thought of.

You're leading me to believe that you are not grasping what the
argument is. When you allude to linear systems theory, you seem to
think that we are talking wabout passing square waves or measuring the
output of a speaker in terms of frequency and phase response.

That is not what the argument is about. I am talking about the spatial
nature of sound. To illustrate the difference, think about a surround
sound system. Surely you would admit that recording and reproducing
in surround sound would come closer to the real thing than two
channel, yes? This is because the direction from which the ambience
arrives at the listener is all important; I would say more important
(to realism) than even frequency and phase response.

Now examine Dunlavy's statements. He says that if your speakers are
accurate, then all of the recorded ambience will come through. So well
that he has examples of recordings where he can't tell the
reproduction from the real thing. What I am trying to point out is
that no amount of accuracy can make up for the loss of the other
channels. Surround sound, even stereo, would be superfluous if
"accuracy" were sufficient for realism. His statements about the
accuracy of his speakers don't even address the real problem, which is
spatial reproduction. Now, from that point of understanding what the
argument is, I might be right and I might be wrong; I am posting all
this to invite him to join in the argument and talk about something
other than his preprogrammed line.

I am not alone or insane when I say all this. Andre Yew has said there
is no point in talking about accuracy until a theory of spatial
reproduction has been developed. Jim Johnston in another thread has
said:

> You've left something out that is very fundamental, and that's the
> issues of soundfield capture and miking. With 2-channel
> recordings, the captured soundfield is deficient in nearly every
> paramater, certainly deficient enough that there's no meaning to the
> word "accuracy".

> Accuracy later down the chain allows you to DELIVER whatever you
> captured accurately, and yes, it IS possible to determine the basic
> accuracy of the delivery. The worst problems come before the signal
> is turned into an electrical signal at all.

JohnO continues:

> I think as long as you're discussing your subjective preferences
> there are no problems but you display symptoms of a classic crank
> otherwise. It's not been a problem in this moderated newsgroup,
> but I would consider it one if it ends up in chasing off one of
> the few designers that post to this group.

All right, let me ask you something. In the last two postings, Dunlavy
has given his fanciful characterization of concert hall acoustics as a
comb filtering effect between the direct sound and a single reflection
from the back of the hall. That's the frequency response of a concert
hall. He then contrasts that with the comb filtering you get with the
much shorter time of reflection for a home listening room, and says
that's the frequency response of the listening room. Why haven't you,
and all the rest of the readers, jumped on him for that? Is your
knowledge of acoustics just as limited? I'm no acoustics expert, but I
do know about room modes, reverberation, absorption coefficients at
various frequencies, room gain, high frequency dispersion, and
probably a few more factors that contribute to a hall's frequency
response.

As for my being the classic crank, I certainly would not keep saying
the same stuff over and over again if I thought it was getting across;
I am very conscious of that. Just give me some indication that you see
my point, then engage the argument as it is and respond to me. If I
say that the type of accuracy that you have in mind is not the point,
don't respond by saying "You must be wrong because what you're
advocating wouldn't be accurate."

In fact, why don't I lay it out for you again, in the simplest
possible terms, so we can either go on or stop the thread:

1. The underlying assumption of the thread is that the more accurate
the loudspeaker, the more it will sound like the real thing. This
refers to accuracy of a measured response of the output of the speaker
with respect to the input signal.

2. But in order to maintain this accuracy all the way to the listener,
it is necessary to have a direct firing speaker with narrow dispersion
pattern in a relatively dead room, so that reflections can't interfere
with the purity of the direct sound.

3. My argument is that this theory disregards the spatial nature of
sound; that in fact, the type of sound field presented by such an
arrangement is so unlike the original that it cannot work. The
difference is easily audible. In attempting to achieve one kind of
accuracy, similarity of a measured output to the input signal, we are
sacrificing the real goal of accuracy of the resultant sound compared
to the real thing. This happens to a great enough extent that a new
theory of soundfield reproduction is called for.

In your response, please tell me how, or by what theory, "accurate"
two channel reproduction can sound like a real sound field in a real
hall. After you have done that, tell me why all those fools keep
talking about Ambisonics, surround sound, 3-D audio, sonic holography,
reverberant fields, loudspeaker radiation patterns, etc etc.

My goal is to get you to admit that "accuracy" may not be a sufficient
condition for the reproduction to sound exactly like the real
thing. We can proceed from there.

Gary Eickmeier

[John Ongtooguk]

Gary Eickmeier/Susan Andrus (imag...@gte.net) wrote:

: You're leading me to believe that you are not grasping what the

: argument is. When you allude to linear systems theory, you seem to
: think that we are talking wabout passing square waves or measuring the
: output of a speaker in terms of frequency and phase response.
:
: That is not what the argument is about. I am talking about the spatial
: nature of sound. To illustrate the difference, think about a surround
: sound system. Surely you would admit that recording and reproducing
: in surround sound would come closer to the real thing than two
: channel, yes? This is because the direction from which the ambience
: arrives at the listener is all important; I would say more important
: (to realism) than even frequency and phase response.

Current consumer 'surround sound' systems are merely designed for
pleasing effects and do not come closer to the 'real thing', your
Bose 901/surround system included. You can call it 'spatial' or
call it your 'new theory' or 'realism' or whatever you want but
it's still just another euphonic effect, as you are merely guessing
at what the desired effect is and adding it whether it exists in the
recording or not. You admit it above when you say that the desired
surround effect is more important than anything else.

As I've mentioned before all that seems to be at issue here is
your inability to acknowledge that your 'new theory' is just
another type of euphonic reproduction.

: My goal is to get you to admit that "accuracy" may not be a sufficient

: condition for the reproduction to sound exactly like the real
: thing. We can proceed from there.

The only attribute that will allow you to get closer to the 'real
thing' is accuracy and for the systems that we are discussing
accuracy is probably best described by linear systems theory,
whether it's two channels or fifty. Anything is fine for euphonic
effects.

John Ongtooguk (jo...@vcd.hp.com)

[Gary Eickmeier/Susan Andrus]

John Ongtooguk wrote:
>
> Andre Yew (and...@ugcs.caltech.edu) wrote:
>
> : I find it very difficult to talk about radiation patterns of speakers

> : without a soundfield-reproduction theory. Without such a theory,
> : there is no consistent way to rank or predict what patterns work, and
> : we end up with a cut-and-try method where there is no reproducible
> : result.

<snip>
> If you expect 'faithful' or 'accurate' reproduction
> then you need to start considering theory, and be ready to make
> lots of compromises.

Do you mean you have a theory for us to consider? I think Andre's point
was that there isn't any.

>
> A good place to start is with some basic assumptions on how we
> hear, and how it might be possible to accurately reproduce a
> soundfield.

I've got a problem with this already. In a field type system, we don't
need to know anything about how we hear. We just need to reproduce the
sound field, and then let our natural hearing do its job.

> The common assumption currently is that if the sound
> presented to the ears during reproduction is similar to what would
> have been heard while present at the performance, faithful
> reproduction can be achieved.

Time out. This smells suspiciously like a binaural system. I think we
need to define terms before we go any further. Let me explain.

There are two fundamental ways to reproduce a sensory experience.
Duplicate the sensory input, or duplicate the object itself and let your
senses just function normally. An example from the visual world would be
the reproduction of a still life. We could either take a 3-D photo of it,
which would duplicate the sensory input to each eye, or we could make a
wax model of it and just view it with our normal stereo vision. In the
world of audio, we can make a binaural recording and input the result to
the ears via headphones (or speakers, actually). This would be
duplicating the sensory input via signals for each ear. Or, we could
reproduce the entire sound field and let our natural hearing do its
thing. This can be accomplished anechoically if you use a great number of
speakers and an equal number of channels (sound field synthesis as in
Blauert), or you can do it with a recording made a little closer to the
instruments and played back in a real room, which would be our current
stereo system. In either case, the object is to reproduce the entire
sound field, which consists of direct, early reflected, and reverberant
sound fields, in real space, around the listener. It is NOT just two
signals for the ears. Think of a wheat field, or a corn field. It is big,
three dimensional, and all around you.

> This neglects some effects due
> to the impact of cognition on hearing but it's still the basic
> assumption that one has to start with in audio.

I don't think so. See above.

> We then quickly
> end up appealing to linear systems theory as the outer and middle
> ears in the static case are now usually regarded as linear filters,
> where the impulse response in the time domain or transfer
> function the frequency domain describe how sound is modified
> on it's way to the inner ear, modifications that along with
> differences between what is heard with both ears largely define
> spatial hearing.

I don't understand this sentence, and would ask John to expand on it if
he really does (understand what he just said).

> It's common now to be able to take an anechoic
> recording and add the impulse response of some room to the response
> of our ears and have the ability to pretty accurately hear
> a reproduced soundfield, plus do many other neat things with 3D
> audio. Check out the many references available for a better
> description.

I'm not sure why he's bringing up 3-D Audio, which is a subset of
binaural. We were talking about stereo. And not with anechoic recordings.
>
> The theory of how we hear and how we might be able to accurately
> reproduce soundfields suggests that we need to pay attention
> to things like 'impulse responses' and 'transfer functions',
> where we need to pay attention to time domain performance in
> addition to our usual attention to the frequency domain, and
> where it's apparent that we may need to reproduce some pretty
> subtle details.

This is an unsupported assertion, kind of trying to slip one in on us.
"The theory of how we hear and how we might be able to accurately
reproduce soundfields" is what we want you to tell us about, John. What
is the theory? This is the original question. You can't just gloss over
it and assume that we all know what it is. How much time domain
performance is audible?

> This means that it's not prudent to bounce lots
> of sound off of walls and such, that we can't just add more
> channels for pleasing effects only as we need to be able to
> reproduce specific impulse responses at a specific listening
> location.

Just tell me why, and I'm more than willing to listen.

> This also means that we don't have much chance of
> obtaining a large listening area. And this also means that even
> though 'radiation pattern' is a moot point as we need a decent
> impulse/step response for such reproduction regardless of
> dispersion, a wide dispersion speaker in a lively environment
> usually doesn't work well for this type of effort.

You have established no basis for saying this, and I am not buying it
anyway. Real music has a large listening area. Why can't the
reproduction, if it's a field type system?

> While stereo
> obviously isn't 'real 3D' audio the above helps to explain
> why some systems allow more faithful reproduction in the sector
> of the soundfield that stereo can reproduce, and why such
> systems can even do better than 'surround systems' in that
> task.

Another assertion. Better than surround systems? Live music is a surround
system.
>
> A lot of work has been done in spatial hearing, 3D audio,
> room simulation, virtual displays ,etc., and while a lot more
> work needs to be done it seems that we have a basic idea on
> what might be required for accurate 'soundfield reproduction'.

You apparently don't know what a sound field is, or you have a different
definition than I do. How can the whole sound field be reproduced by a
pair of monopolar speakers? Where does the rest of the field come from?

> As usual we need to sort out what's practical and what we're
> willing to pay for and listen to, but in doing so we should be
> able to identify and acknowledge the compromises that we're
> making.

If by this you mean we don't have enough money to be able to afford a
really accurate system, so we make do with stereo and surround sound, I
would agree. Perfect accuracy would require an anechoic listening
environment and over 120 playback channels or signal processing
equivalent. It would be restrictive in listening position, like bad
stereo.

I think good stereo, correctly done, has the potential for unrestricted
listening position, three dimensional sound, and very realistic
reproduction. All we need is a sound field reproduction theory to
accomplish it. Discreet surround shows promise. At least it does create
a sound field, and you can sit anywhere in a theater.

How are we doing, Andre?

Gary Eickmeier

[John Ongtooguk]

Gary Eickmeier/Susan Andrus (imag...@gte.net) wrote:

: John Ongtooguk wrote:
: >
: > A good place to start is with some basic assumptions on how we

: > hear, and how it might be possible to accurately reproduce a
: > soundfield.

: I've got a problem with this already. In a field type system, we don't
: need to know anything about how we hear. We just need to reproduce the
: sound field, and then let our natural hearing do its job.

If you don't care to know what's important for spatial hearing
then you'll never really know what's important for attempts at
accurate reproduction.

: > The common assumption currently is that if the sound

: > presented to the ears during reproduction is similar to what would
: > have been heard while present at the performance, faithful
: > reproduction can be achieved.

: There are two fundamental ways to reproduce a sensory experience.

: Duplicate the sensory input, or duplicate the object itself and let your

: senses just function normally ound ...... It is NOT just two
: signals for the ears....

Since we have two ears it is always 'just two signals for the ears'.
Regardless of how we attempt to reproduce sound the signals at the
eardrum need to be similar if we want the reproductions to sound
similar. This is probably the fundamental error that you've made
with your 'new theory of stereo' as you seem to think otherwise.

: > We then quickly

: > end up appealing to linear systems theory as the outer and middle
: > ears in the static case are now usually regarded as linear filters,
: > where the impulse response in the time domain or transfer
: > function the frequency domain describe how sound is modified
: > on it's way to the inner ear, modifications that along with
: > differences between what is heard with both ears largely define
: > spatial hearing.

: I don't understand this sentence, and would ask John to expand on it if
: he really does (understand what he just said).

In addition to interaural level and time differences we use the head
related transfer function (HRTF) for spatial hearing. The transfer
function is largely determined by the shape of our ears and is also
determined by the position of our ears relative to our head and
shoulder. In the frequency domain the transfer function shows how
sound is modified on it's way to the eardrum, and it can also be
described in the time domain with the impulse response. This type
of description, this way of looking at our hearing is similar to
how we treat many other systems using 'linear systems theory'.

: > It's common now to be able to take an anechoic

: > recording and add the impulse response of some room to the response
: > of our ears and have the ability to pretty accurately hear
: > a reproduced soundfield, plus do many other neat things with 3D
: > audio. Check out the many references available for a better
: > description.

: I'm not sure why he's bringing up 3-D Audio, which is a subset of
: binaural. We were talking about stereo. And not with anechoic recordings.

There is obviously plenty of overlap between stereo and 3D audio,
as attempt at stereo reproduction can be viewed as attempts at
reproducing a sector of sound, and most importantly how we hear
and what's important for spatial hearing remains the same.

: > The theory of how we hear and how we might be able to accurately

: > reproduce soundfields suggests that we need to pay attention
: > to things like 'impulse responses' and 'transfer functions',
: > where we need to pay attention to time domain performance in
: > addition to our usual attention to the frequency domain, and
: > where it's apparent that we may need to reproduce some pretty
: > subtle details.

: This is an unsupported assertion, kind of trying to slip one in on us.
: "The theory of how we hear and how we might be able to accurately
: reproduce soundfields" is what we want you to tell us about, John. What
: is the theory? This is the original question. You can't just gloss over
: it and assume that we all know what it is. How much time domain
: performance is audible?

You need to do a lot more reading before making statements like
'unsupported assertion'. I seem to recall that you have a copy
of Blauret's 'Spatial Hearing' so read chapter 5, 'Progress and
Trends since 1982' for starters. There is also plenty on the
WEB to look at. As previously mentioned the theory is simply that
we need to produce similar signals at the eardrums for similar
sounds, and that the work in that has been done in spatial hearing
suggests what's important for that task. The less your efforts
resemble that task the less accurate your efforts will tend to be.

There is nothing to 'gloss over' as this is pretty simple stuff,
but things get difficult quickly when we make the compromises
that are usually required. 'How much time domain performance
is audible' is kind of a vague question - is 'lots' a vague
enough answer ?

: > This means that it's not prudent to bounce lots

: > of sound off of walls and such, that we can't just add more
: > channels for pleasing effects only as we need to be able to
: > reproduce specific impulse responses at a specific listening
: > location.

: Just tell me why, and I'm more than willing to listen.

Simply because you're adding something to the signal that was
not present in the signal to begin with. You've added another
'transfer function' to the signal, room effects in the one case.

: > This also means that we don't have much chance of

: > obtaining a large listening area. And this also means that even
: > though 'radiation pattern' is a moot point as we need a decent
: > impulse/step response for such reproduction regardless of
: > dispersion, a wide dispersion speaker in a lively environment
: > usually doesn't work well for this type of effort.

: You have established no basis for saying this, and I am not buying it
: anyway. Real music has a large listening area. Why can't the
: reproduction, if it's a field type system?

'Real music has a large listening area' seems to assume that live
music will always sound the same regardless of listening position,
which isn't really correct, unless perhaps one is in a range of far
field positions. I think that the reason that we always end up with
a small sweet spot is because we are attempting to reproduce a
continuous field with a small number of sources.

: > While stereo

: > obviously isn't 'real 3D' audio the above helps to explain
: > why some systems allow more faithful reproduction in the sector
: > of the soundfield that stereo can reproduce, and why such
: > systems can even do better than 'surround systems' in that
: > task.

: Another assertion. Better than surround systems? Live music is a surround
: system.

You are confusing pleasant sounding ambient effects with accurate
imaging, as adding a few more channels, some delay, and bouncing more
sound around doesn't mean more accurate results. Surround systems
are getting better but net effect is still largely one of more
changes to the signal during reproduction.

: > A lot of work has been done in spatial hearing, 3D audio,

: > room simulation, virtual displays ,etc., and while a lot more
: > work needs to be done it seems that we have a basic idea on
: > what might be required for accurate 'soundfield reproduction'.

: You apparently don't know what a sound field is, or you have a different
: definition than I do. How can the whole sound field be reproduced by a
: pair of monopolar speakers? Where does the rest of the field come from?

'Real 3D' only happens when the proper signals are presented to the
ears, which means that it doesn't happen with conventional stereo.
The ability to hear a field, or part of one, is initially contained
in the signals to be reproduced.

: > As usual we need to sort out what's practical and what we're

: > willing to pay for and listen to, but in doing so we should be
: > able to identify and acknowledge the compromises that we're
: > making.

: If by this you mean we don't have enough money to be able to afford a
: really accurate system, so we make do with stereo and surround sound, I
: would agree. Perfect accuracy would require an anechoic listening
: environment and over 120 playback channels or signal processing
: equivalent. It would be restrictive in listening position, like bad
: stereo.
:
: I think good stereo, correctly done, has the potential for unrestricted
: listening position, three dimensional sound, and very realistic
: reproduction. All we need is a sound field reproduction theory to
: accomplish it. Discreet surround shows promise. At least it does create
: a sound field, and you can sit anywhere in a theater.

As I mentioned previously if all you're interested in is 'realistic'
sound, which is different than 'accurate', then it doesn't really
matter what you want to do. Just change your system around until
it sounds 'realistic'.

John Ongtooguk (jo...@vcd.hp.com)

[Andre Yew]

jo...@vcd.hp.com (John Ongtooguk) writes:

> A lot of work has been done in spatial hearing, 3D audio,
> room simulation, virtual displays ,etc., and while a lot more
> work needs to be done it seems that we have a basic idea on
> what might be required for accurate 'soundfield reproduction'.

Yes, all of your points are well and good, but how do you deliver
this 3D audio or soundfield reproduction to the consumer? What kinds
of speakers, how many of them, what kind of decoder, what kind of
listening room do they need? That is what I meant by a soundfield
reproduction theory. Blumlein knew many decades ago roughly two kinds
of spatial cues and designed his system around it. Gerzon followed
the same path and greatly expanded it. Those are two examples of a
consistent soundfield reproduction theory.

To be blunt, all the talk about accuracy and phase linearity, and
other attributes of speakers are merely exercises in personal
listener preference until they are put in the context of a soundfield
reproduction theory (anyone have a shorter, less cumbersome name for
this?), and we can judge their importance within the theory. Without
any kind of framing theory around speaker attributes, it becomes very
difficult to weigh compomises.

Don't you find it disturbing that many posts on loudspeaker accuracy
don't even mention anything about mics, miking positions, and
patterns?

[John Ongtooguk]

Andre Yew (and...@ugcs.caltech.edu) wrote:

: jo...@vcd.hp.com (John Ongtooguk) writes:

: > A lot of work has been done in spatial hearing, 3D audio,
: > room simulation, virtual displays ,etc., and while a lot more
: > work needs to be done it seems that we have a basic idea on
: > what might be required for accurate 'soundfield reproduction'.

: Yes, all of your points are well and good, but how do you deliver
: this 3D audio or soundfield reproduction to the consumer? What kinds
: of speakers, how many of them, what kind of decoder, what kind of
: listening room do they need? That is what I meant by a soundfield
: reproduction theory. Blumlein knew many decades ago roughly two kinds
: of spatial cues and designed his system around it. Gerzon followed
: the same path and greatly expanded it. Those are two examples of a
: consistent soundfield reproduction theory.
:
: To be blunt, all the talk about accuracy and phase linearity, and
: other attributes of speakers are merely exercises in personal
: listener preference until they are put in the context of a soundfield
: reproduction theory (anyone have a shorter, less cumbersome name for
: this?), and we can judge their importance within the theory. Without
: any kind of framing theory around speaker attributes, it becomes very
: difficult to weigh compomises.

With any attempt at recording and reproduction we can compare
the techniques, hardware, preferences, etc., with what is
required for accurate spatial reproduction, which I'm assuming
is the topic of interest, to see how far removed the effort
is from the ideal. Are the efforts converging towards what is
required for accurate reproduction, or do the efforts suggest
that all that can be obtained are euphonic effects ? In the
context of a desired flat, or at least smooth frequency response
does turning up the bass all the way suggest an attempt at
accurate reproduction, or does it suggest euphonic effects ?
We appear to have a similar standard of performance for spatial
reproduction but it's not recognized as such, rather most
people are content with 'turning up the spatial all the way' :^)

: Don't you find it disturbing that many posts on loudspeaker accuracy

: don't even mention anything about mics, miking positions, and
: patterns?

Consumers have little control over those variables so they don't
generate as much interest.

I'm not suggesting that anyone needs to scrap their systems,
rather I'm just trying to point a ready benchmark of performance
for spatial reproduction, a benchmark that is useful even for
evaluating conventional stereo.

John Ongtooguk (jo...@vcd.hp.com)

[Gary Eickmeier/Susan Andrus]

John Ongtooguk wrote:

> Since we have two ears it is always 'just two signals for the ears'.
> Regardless of how we attempt to reproduce sound the signals at the
> eardrum need to be similar if we want the reproductions to sound
> similar. This is probably the fundamental error that you've made
> with your 'new theory of stereo' as you seem to think otherwise.
>

> In addition to interaural level and time differences we use the head
> related transfer function (HRTF) for spatial hearing. The transfer
> function is largely determined by the shape of our ears and is also
> determined by the position of our ears relative to our head and
> shoulder. In the frequency domain the transfer function shows how
> sound is modified on it's way to the eardrum, and it can also be
> described in the time domain with the impulse response. This type
> of description, this way of looking at our hearing is similar to
> how we treat many other systems using 'linear systems theory'.

> There is obviously plenty of overlap between stereo and 3D audio,
> as attempt at stereo reproduction can be viewed as attempts at
> reproducing a sector of sound, and most importantly how we hear
> and what's important for spatial hearing remains the same.

> As previously mentioned the theory is simply that

> we need to produce similar signals at the eardrums for similar
> sounds, and that the work in that has been done in spatial hearing
> suggests what's important for that task. The less your efforts
> resemble that task the less accurate your efforts will tend to be.
> >

> 'Real 3D' only happens when the proper signals are presented to the
> ears, which means that it doesn't happen with conventional stereo.
> The ability to hear a field, or part of one, is initially contained
> in the signals to be reproduced.

These quotes make it plain that, as I suspected, Mr. Ongtooguk is
confusing stereophonic and binaural. This is something I have covered
at length in past postings, and if it didn't "take" then, there is no
point in going over it again.

Fifty years ago, both Harry F. Olson and William B. Snow cautioned us
that the two terms binaural and stereophonic tend to be continually
confused with each other. Some good reading for John or anyone else to
get into would be Snow, William B, "Basic Principles of Stereophonic
Sound", Journal of the SMPTE, Nov 1953, or the anthology Stereophonic
Techniques, edited by John Eargle and available from the Audio
Engineering Society.

If Mr. Ongtooguk disagrees with this assessment, I invite him to lay
out for us the difference between binaural and stereophonic
systems. If the theory (for stereo) is "simply that we need to produce
similar signals at the eardrums for similar sounds", then what is the
theory for binaural? If the theory is that "Since we have two ears it
is always 'just two signals for the ears'", then what is happening
with 3, 4, and 5 channel systems? Are more channels just foolishness?

Gary Eickmeier

[David Wareing]

I think the point is that humans use binaural hearing for sound
localization. Neglecting other imporant factors such as the way the
binaural signals change with the 6 degrees of freedom (Head Tracking,
soundfield sampling etc.) sound conduction through body tissue(Bone
conduction) Vision, cognition, history etc. Binaural is how we do it!

Stereo only approximates the required binaural imput which may be
divided into direct and various components which are reflected and
delayed.

Soundfield reconstuction recreates the sound field (If one can do
this) including all the reflections and then you can walk about in it
and get all the correct binaural signals. Not just in one place and
without worrying how spatial hearing works too much. If you want to
walk around a lot and have your soundfield accurate and automatically
get the Binaural signals we normally hear, then Gerzon suggest a few
million channels or so.

Loudspeaker binaural gives you binaural signals using your own head
rather than that of a dummy, In the case of "stereo-dipole" you can
rotate your head and get more or less the correct binaural changes. It
can also to a large extent reproduce (some of the bits the brain uses
such as ILDs and ITDs) the important lateral refections that are
unknown to science according to "your" theory. Stereo without a room
cannot do this, with a room you get a lot of crap thown in as well.
There is no correct or accurate or realistic answer for Stereo. Go
back to the drawing board.........or continue going around in circles
folks!

Where have I gone wrong so far?
David.

http://www.users.dircon.co.uk/~wareing/3daudio.htm

On 9 Jul 1998 18:18:49 GMT, Gary Eickmeier/Susan Andrus
<imag...@gte.net> wrote:

>John Ongtooguk wrote:
>
>> Since we have two ears it is always 'just two signals for the ears'.
>> Regardless of how we attempt to reproduce sound the signals at the
>> eardrum need to be similar if we want the reproductions to sound
>> similar. This is probably the fundamental error that you've made
>> with your 'new theory of stereo' as you seem to think otherwise.
>>

>> In addition to interaural level and time differences we use the head
>> related transfer function (HRTF) for spatial hearing. The transfer
>> function is largely determined by the shape of our ears and is also
>> determined by the position of our ears relative to our head and
>> shoulder. In the frequency domain the transfer function shows how
>> sound is modified on it's way to the eardrum, and it can also be
>> described in the time domain with the impulse response. This type
>> of description, this way of looking at our hearing is similar to
>> how we treat many other systems using 'linear systems theory'.

>> There is obviously plenty of overlap between stereo and 3D audio,
>> as attempt at stereo reproduction can be viewed as attempts at
>> reproducing a sector of sound, and most importantly how we hear
>> and what's important for spatial hearing remains the same.
>

>> As previously mentioned the theory is simply that
>> we need to produce similar signals at the eardrums for similar
>> sounds, and that the work in that has been done in spatial hearing
>> suggests what's important for that task. The less your efforts
>> resemble that task the less accurate your efforts will tend to be.
>> >

>> 'Real 3D' only happens when the proper signals are presented to the
>> ears, which means that it doesn't happen with conventional stereo.
>> The ability to hear a field, or part of one, is initially contained
>> in the signals to be reproduced.
>

[John Ongtooguk]

David Wareing (war...@dircon.co.uk) wrote:
: I think the point is that humans use binaural hearing for sound

: localization. Neglecting other imporant factors such as the way the
: binaural signals change with the 6 degrees of freedom (Head Tracking,
: soundfield sampling etc.) sound conduction through body tissue(Bone
: conduction) Vision, cognition, history etc. Binaural is how we do it!

:
: Loudspeaker binaural gives you binaural signals using your own head

: rather than that of a dummy, In the case of "stereo-dipole" you can
: rotate your head and get more or less the correct binaural changes. It
: can also to a large extent reproduce (some of the bits the brain uses
: such as ILDs and ITDs) the important lateral refections that are
: unknown to science according to "your" theory. Stereo without a room
: cannot do this, with a room you get a lot of crap thown in as well.
: There is no correct or accurate or realistic answer for Stereo. Go
: back to the drawing board.........or continue going around in circles
: folks!
:
: Where have I gone wrong so far?

You haven't from what I've seen. I would only add an item that I
mentioned earlier, which you may or may not agree with, which is
that within a sector of a soundfield stereo can provide better
localization than the typical 'surround' offerings. I agree that
for 'there is no accurate solution' for stereo when attempting
to reproduce a larger soundfield.

The next question though is if binaural is how we do it, does
it provide a good benchmark for estimating the performance of
various attempts at faithful spatial reproduction ? I think
that it does.

: David.
:
: http://www.users.dircon.co.uk/~wareing/3daudio.htm

When I plugged the above in I found one of my favorite sites -
thanks for putting it together and keeping it up !

John Ongtooguk (jo...@vcd.hp.com)

[Gary Eickmeier/Susan Andrus]

David Wareing wrote:
>
> I think the point is that humans use binaural hearing for sound
> localization. Neglecting other imporant factors such as the way the
> binaural signals change with the 6 degrees of freedom (Head Tracking,
> soundfield sampling etc.) sound conduction through body tissue(Bone
> conduction) Vision, cognition, history etc. Binaural is how we do it!

What is "the 6 degrees of freedom"?

>
> Stereo only approximates the required binaural imput which may be
> divided into direct and various components which are reflected and
> delayed.

No, again I say please do not confuse stereo and binaural. Stereo is a
completely different system, or concept. It is a field type system, which
you allude to below:

>
> Soundfield reconstuction recreates the sound field (If one can do
> this) including all the reflections and then you can walk about in it
> and get all the correct binaural signals. Not just in one place and
> without worrying how spatial hearing works too much.

You are correct sir.

> If you want to
> walk around a lot and have your soundfield accurate and automatically
> get the Binaural signals we normally hear, then Gerzon suggest a few
> million channels or so.

Again, no, you are not getting binaural channels with a field type
system. And no, it is not necessary to have a few million channels.

The simplest example would be a recording of a guitar. We make a
close-miked recording of the guitar, then play it back on an
omnidirectional speaker, positioned geometrically similarly to the
position of the guitar in the original space. With only a single channel,
we can have a realistic reproduction of a guitar playing in a real
acoustic space, and we can walk all around it, and hear its postition in
space with our normal hearing mechanism. But neither the recording nor
the reproduction referred to or had anything to do with how we hear; we
simply reproduced the sound field and used our normal hearing to listen
to it. A dog, a cat, or a bat would perceive the reproduction the same
way they perceive the live sound. The SYSTEM has nothing to do with how
we hear because it is a field type system.

>
> Loudspeaker binaural gives you binaural signals using your own head
> rather than that of a dummy, In the case of "stereo-dipole" you can
> rotate your head and get more or less the correct binaural changes. It
> can also to a large extent reproduce (some of the bits the brain uses
> such as ILDs and ITDs) the important lateral refections that are
> unknown to science according to "your" theory.

Whose theory???

> Stereo without a room
> cannot do this, with a room you get a lot of crap thown in as well.
> There is no correct or accurate or realistic answer for Stereo. Go
> back to the drawing board.........or continue going around in circles
> folks!
>
> Where have I gone wrong so far?

Your main error, like John's, is in thinking that stereo is just an
"extension", or imperfect version, of binaural.

And what is with this "stereo dipole" nonsense? There were even some
guys in the last AES Journal who had an article published on this. For
those who haven't read it, it is two speakers playing loudspeaker
binaural with crosstalk cancellation and all, and the big deal is
supposed to be that the speakers are very close together. Well, Carver
was doing this in the mid seventies with his Sonic Holography, as I
recall. So how did these guys get published, and what do you think is
new about it??

Gary Eickmeier

[Stewart Pinkerton]

Gary Eickmeier/Susan Andrus <imag...@gte.net> writes:

>David Wareing wrote:
>>
>> I think the point is that humans use binaural hearing for sound
>> localization. Neglecting other imporant factors such as the way the
>> binaural signals change with the 6 degrees of freedom (Head Tracking,
>> soundfield sampling etc.) sound conduction through body tissue(Bone
>> conduction) Vision, cognition, history etc. Binaural is how we do it!
>
>What is "the 6 degrees of freedom"?

Up/down, left/right, forward/back. It's a term more commonly used in
robotics.

--

Stewart Pinkerton | Music is art, audio is engineering

[Richard D Pierce]

In article <6o7875$rf5$1...@agate.berkeley.edu>,

Stewart Pinkerton <a...@borealis.com> wrote:
>Gary Eickmeier/Susan Andrus <imag...@gte.net> writes:
>>> Neglecting other imporant factors such as the way the
>>> binaural signals change with the 6 degrees of freedom
>>

>>What is "the 6 degrees of freedom"?
>
>Up/down, left/right, forward/back. It's a term more commonly used in
>robotics.

That's only three degrees of freedom.

More precisely, it is a VERY common term in a wide variety of fields,
from geometry to mechanical engineering to flight. It's a VERY common
term.

The common usage of the term refers to 3 degrees of translation
freedom along 3 orthogonal axes (up-down, left-right, forward-back, as
Stewart mentioned) an 3 degrees of rotational freedom around those
same orthogonal axes.

It's a truly fundamental concept that even rates its own field of
study in mechanical engineering: kinematics. Ignorance of kinematics
during design of a prouct is done at the peril of the engineer and the
user. Witness the difficulty of setting up a Linn turntable: this is a
direct conseuqence of ignoring kinematic prnciples during the "design"
of the product. With relatively few design improvements and almost no
added cost, the product could be made so that setup is FAR easier, FAR
more reliable, completely repeatable and now removed from the realm of
the over-charging tweako-specialist (many of whom also fail to
recognize the kinematic misdesigm of the product) and puts it where it
belongs: in the hands of the user.

--
+-----------------------------------+
| Dick Pierce |
| Professional Audio Development |
| Transducer Design and Measurement |

[David Wareing]

On 11 Jul 1998 02:07:49 GMT, Gary Eickmeier/Susan Andrus
<imag...@gte.net> wrote:

>David Wareing wrote:
>>
>> I think the point is that humans use binaural hearing for sound
>> localization. Neglecting other imporant factors such as the way the
>> binaural signals change with the 6 degrees of freedom (Head Tracking,
>> soundfield sampling etc.) sound conduction through body tissue(Bone
>> conduction) Vision, cognition, history etc. Binaural is how we do it!

>What is "the 6 degrees of freedom"?

The possible movements (of the head in this case): Three components of
rotation at right angles and three linear movements at right angles.

>>
>> Stereo only approximates the required binaural imput which may be
>> divided into direct and various components which are reflected and
>> delayed.

>No, again I say please do not confuse stereo and binaural. Stereo is a
>completely different system, or concept. It is a field type system, which
>you allude to below:

I don't feel confused. If both are correct then the correct field
system produces the correct binaural components at the ears. Stereo
is not a correct field system and does not produce the correct
Binaural.

>>
>> Soundfield reconstuction recreates the sound field (If one can do
>> this) including all the reflections and then you can walk about in it
>> and get all the correct binaural signals. Not just in one place and
>> without worrying how spatial hearing works too much.

>You are correct sir.

Sir?

>
>> If you want to
>> walk around a lot and have your soundfield accurate and automatically
>> get the Binaural signals we normally hear, then Gerzon suggest a few
>> million channels or so.

>Again, no, you are not getting binaural channels with a field type
>system. And no, it is not necessary to have a few million channels.

>The simplest example would be a recording of a guitar. We make a
>close-miked recording of the guitar, then play it back on an
>omnidirectional speaker, positioned geometrically similarly to the
>position of the guitar in the original space. With only a single channel,
>we can have a realistic reproduction of a guitar playing in a real
>acoustic space, and we can walk all around it, and hear its postition in
>space with our normal hearing mechanism. But neither the recording nor
>the reproduction referred to or had anything to do with how we hear; we
>simply reproduced the sound field and used our normal hearing to listen
>to it. A dog, a cat, or a bat would perceive the reproduction the same
>way they perceive the live sound. The SYSTEM has nothing to do with how
>we hear because it is a field type system.

I have not argued that your system is not pretty realistic or just
euphonic, I don't know. Mono (the above example) is pretty perfect if
you want a sound from the position of the speaker and are not too
worried by some difference in the radiation pattern.

>>
>> Loudspeaker binaural gives you binaural signals using your own head
>> rather than that of a dummy, In the case of "stereo-dipole" you can
>> rotate your head and get more or less the correct binaural changes. It
>> can also to a large extent reproduce (some of the bits the brain uses
>> such as ILDs and ITDs) the important lateral refections that are
>> unknown to science according to "your" theory.

>Whose theory???

I may have lost sight of your theory under the weight of other
material.

>> Stereo without a room
>> cannot do this, with a room you get a lot of crap thown in as well.
>> There is no correct or accurate or realistic answer for Stereo. Go
>> back to the drawing board.........or continue going around in circles
>> folks!

>> Where have I gone wrong so far?

>Your main error, like John's, is in thinking that stereo is just an
>"extension", or imperfect version, of binaural.

Extension?

>And what is with this "stereo dipole" nonsense? There were even some
>guys in the last AES Journal who had an article published on this. For
>those who haven't read it, it is two speakers playing loudspeaker
>binaural with crosstalk cancellation and all, and the big deal is
>supposed to be that the speakers are very close together. Well, Carver
>was doing this in the mid seventies with his Sonic Holography, as I
>recall. So how did these guys get published, and what do you think is
>new about it??

Oh dear me! These "guys" know what they are talking about. Perhaps
you have not heard the CD they produced and I doubt you will now!
"How did these guys ever get published" will go down as the quote of
the decade in scientific and audio circles.

I don't want to go in circles, so I will leave it there.

Byeeeeee
David.

[Andre Yew]

Gary Eickmeier/Susan Andrus <imag...@gte.net> writes:

>The simplest example would be a recording of a guitar. We make a
>close-miked recording of the guitar, then play it back on an
>omnidirectional speaker, positioned geometrically similarly to the
>position of the guitar in the original space.

I think this is a Von Schweikertism --- the guitar like any other
sound-producing device whose physical dimensions are approximately
equal to the wavelengths of the sound its producing will not have a
uniform or omnidirectional radiation pattern. What you will have is
an omni speaker (if any thing like that even exists) playing back a
recording a guitar in a room. As you walk around the speaker, you
will not hear the same thing as if you were walking around the guitar
and guitar player.

To simulate what one would hear if one were to place one's head at
the mic, you would need to mic it appropriately and reproduce it
using many, many speakers, but what you would hear would only be what
the mics heard at their location, never what you may have heard if
you stood behind the guitar player --- even if you did walk around
your playback system.

[jj, curmudgeon and tiring philalethist]

In article <6o8c7l$h...@news01.aud.alcatel.com>,

David Wareing <war...@dircon.co.uk> wrote:
>I don't feel confused. If both are correct then the correct field
>system produces the correct binaural components at the ears. Stereo
>is not a correct field system and does not produce the correct
>Binaural.

It can do so at one point, with a very dead room, and the right
kind of Atal cancellation.

>>Again, no, you are not getting binaural channels with a field type
>>system. And no, it is not necessary to have a few million channels.

Um, then how many are necessary?

[John Ongtooguk]

Gary Eickmeier/Susan Andrus (imag...@gte.net) wrote:

: David Wareing wrote:
:
: > Soundfield reconstuction recreates the sound field (If one can do

: > this) including all the reflections and then you can walk about in it
: > and get all the correct binaural signals. Not just in one place and
: > without worrying how spatial hearing works too much.

: You are correct sir.

: > If you want to

: > walk around a lot and have your soundfield accurate and automatically
: > get the Binaural signals we normally hear, then Gerzon suggest a few
: > million channels or so.

: Again, no, you are not getting binaural channels with a field type

: system. And no, it is not necessary to have a few million channels.

You seemed to agree and then you don't. Signals at the eardrums are
signals at the eardrums, regardless of what reproduction technology
we are using or whether we are listening to live music. If we were
able to reproduce the signals at the eardrums that are heard when
we listen to live music, regardless of the methods, then we would
for the most part, disregarding cognitive effects, perceive the
reproduced sound as being similar to live music. An 'accurate'
soundfield would sound similar to 'accurate' binaural reproduction
at the same listening position and both would sound like live music
heard at a similar listening position. You may choose to ignore
how we appear to hear but it doesn't mean that how we hear changes
when we listen to different musical performances, recorded or not,
instead different attempts at musical reproduction produce different
signals at the eardrums, with different levels of fidelity.

John Ongtooguk (jo...@vcd.hp.com)

[John Ongtooguk]

Gary Eickmeier/Susan Andrus (imag...@gte.net) wrote:

: John Ongtooguk wrote:
:
: > 'Real 3D' only happens when the proper signals are presented to the

: > ears, which means that it doesn't happen with conventional stereo.
: > The ability to hear a field, or part of one, is initially contained
: > in the signals to be reproduced.

: These quotes make it plain that, as I suspected, Mr. Ongtooguk is

: confusing stereophonic and binaural. This is something I have covered
: at length in past postings, and if it didn't "take" then, there is no
: point in going over it again.

Binaural is 'real 3D', which again makes it clear that there is
no confusion on the issue. I'm guessing that your confusion with
the comparison is one of thinking that stereo is merely a subset
a binaural, which I and others have stated that it isn't (I can
think of some limited cases where they might be similar but in
the general case they aren't), while the comparison is actually
one of describing how we hear in terms of a current reproduction
technology.

: ..... I invite him to lay

: out for us the difference between binaural and stereophonic

: systems. If the theory (for stereo) is "simply that we need to produce
: similar signals at the eardrums for similar sounds", then what is the
: theory for binaural? If the theory is that "Since we have two ears it
: is always 'just two signals for the ears'", then what is happening

: with 3, 4, and 5 channel systems? Are more channels just foolishness?

In the context of faithful spatial reproduction two channels or a
dozen channels are just foolishness if they don't result in
faithful reproduction. 'Surround sound' has been basically designed
to provide movie effects, to 'surround' the listener with ambient
effects, and wasn't really designed to provide faithful spatial
reproduction using multiple high quality, full bandwidth channels.
Multiple channels offer the possibility of a less restrictive
listening position but unlike it's been previously stated the
improvement for faithful reproduction is modest. With 'surround
sound' the improvements might be substantial because the
requirements are modest.

Binaural is merely the attempt to deliver the sounds heard at
the start of the inner ear and from a specific listening position,
to each ear. It's attempt which offers the possibility of faithful
spatial reproduction. Stereo is an attempt to offer a soundstage
at a listening position and based primarily upon offering left-right
cues. Stereo could only be considered a subset of binaural if the
3D soundstage was similar in extent to well executed stereo,
basically a sector of space, and the recordings offered similar
localization in the recorded space.

John Ongtooguk (jo...@vcd.hp.com)

[Gary Eickmeier/Susan Andrus]

David Wareing wrote:

> I don't feel confused. If both are correct then the correct field
> system produces the correct binaural components at the ears. Stereo
> is not a correct field system and does not produce the correct
> Binaural.

This is a headline statement if I ever saw one! Stereo is not a
correct field system? Can you expand on that? Does not produce the
correct binaural? I am telling you again, stereo is not a system which
produces signals for the ears. I'm not sure what you mean by "the
correct binaural", but maybe another question could clear this
up. Does live sound produce "a correct binaural"? If the answer is
yes, then I guess we are back to the first question, what is wrong
with stereo. As you understand it. If the answer is no, we are all in
trouble.

> I have not argued that your system is not pretty realistic or just
> euphonic, I don't know. Mono (the above example) is pretty perfect if
> you want a sound from the position of the speaker and are not too
> worried by some difference in the radiation pattern.

OK, make the radiation pattern the same as the instrument. That was
only a simple example. I wrote a whole article on stereo as a field
type system. It used the example of a speaker for each instrument,
arranged on stage geometrically similarly to the positions of the
original instruments. It is just an example of how a "possible"
recording and reproduction system could be conceived with no reference
whatsoever to the human hearing mechanism. It's hard to believe, but
even though there are two channels in current stereo, it is not a
system of supplying two signals for your two ears.

> >And what is with this "stereo dipole" nonsense? There were even
> some >guys in the last AES Journal who had an article published on
> this. For >those who haven't read it, it is two speakers playing
> loudspeaker >binaural with crosstalk cancellation and all, and the
> big deal is >supposed to be that the speakers are very close
> together. Well, Carver >was doing this in the mid seventies with his
> Sonic Holography, as I >recall. So how did these guys get published,
> and what do you think is >new about it?? Oh dear me! These "guys"
> know what they are talking about. Perhaps you have not heard the CD
> they produced and I doubt you will now! "How did these guys ever
> get published" will go down as the quote of the decade in scientific
> and audio circles. I don't want to go in circles, so I will leave
> it there.

Be astonished all you want, but you still haven't answered the question:
What is new about this material?

Gary Eickmeier

[Gary Eickmeier/Susan Andrus]

John Ongtooguk wrote:

> You seemed to agree and then you don't. Signals at the eardrums are
> signals at the eardrums, regardless of what reproduction technology
> we are using or whether we are listening to live music. If we were
> able to reproduce the signals at the eardrums that are heard when
> we listen to live music, regardless of the methods, then we would
> for the most part, disregarding cognitive effects, perceive the
> reproduced sound as being similar to live music. An 'accurate'
> soundfield would sound similar to 'accurate' binaural reproduction
> at the same listening position and both would sound like live music
> heard at a similar listening position. You may choose to ignore
> how we appear to hear but it doesn't mean that how we hear changes
> when we listen to different musical performances, recorded or not,
> instead different attempts at musical reproduction produce different
> signals at the eardrums, with different levels of fidelity.

I think I see the disconnect here (between me and John), but he will
think it pompous of me to try and explain it. It is something like two
different logic systems, within which we are each convinced we are right.
I can't "break into" his and bust it open for him to be able to see mine,
and he can't understand why I keep saying such "crazy" things.

The confusion between stereo and binaural has its marriage in this "3-D
Audio" business. It is basically loudspeaker binaural, so we can see the
confusion right away. If 3-D audio is more successful at spatial
presentation, then stereo must be somehow incorrect or incomplete (in
John's universe). Well, to fix it, we must need more accurate speakers,
or more dead playback rooms, or a higher ratio of direct sound, and so
on, in a circular argument based on a wrong premise.

If I could bring John (and others) into my universe, the above model for
stereo could be laid to rest, entire new assumptions constructed, and the
sound for all of us could be much more realistic.

As one last point, I want to state that there are advantages to the
stereophonic (field type) system that no other system has, even though it
appears on the surface that binaural (or the latest rage, 3-D Audio)
works better, or is more accurate. Therefore, it behooves us to learn
more about how to do stereo right.

I have tried, in previous posts, to bust people out of the "accuracy"
rut, but I apparently haven't been successful. I'm stumped for any
further analogies and examples. All I can say is go back through my posts
in Deja News, or I'll send you my papers (whoever is interested). I had
an article in the BAS Speaker newsletter a few months ago.

Except for the few who are interested in this stuff, thank you for your
patience.

Gary Eickmeier

[Gary Eickmeier/Susan Andrus]

John Ongtooguk wrote:

> Binaural is 'real 3D', which again makes it clear that there is
> no confusion on the issue. I'm guessing that your confusion with
> the comparison is one of thinking that stereo is merely a subset
> a binaural, which I and others have stated that it isn't (I can
> think of some limited cases where they might be similar but in
> the general case they aren't), while the comparison is actually
> one of describing how we hear in terms of a current reproduction
> technology.

I have no confusion. Stereo is not a subset of binaural. The two are
completely different auditory perspective systems. Confusion of one
with the other has caused great problems in the past, in designing and
implementing stereophonic systems. For example, if you think stereo is
"two signals for the ears" you might think the idea in designing
loudspeakers is to present an "accurate" acoustical signal to the ears
by means of a high ratio of direct sound. This would lead to spatial
compression, when compared to a properly designed and executed field
type system.

> Stereo is an attempt to offer a soundstage
> at a listening position and based primarily upon offering left-right
> cues. Stereo could only be considered a subset of binaural if the
> 3D soundstage was similar in extent to well executed stereo,
> basically a sector of space, and the recordings offered similar
> localization in the recorded space.

There is no equivalency between binaural and stereo. Even if you had
an extremely close miked recording being played back in the original
hall, compared to a binaural recording made in that hall, with the
stereo reproduction you could walk around the room and get different
perspectives. With binaural, the perspective is fixed.

Gary Eickmeier

[Dunlavy Audio Labs]

Please approve and post the following article composed by John
Dunlavy for inclusion on rec audio high end under the thread
"Loudspeaker Accuracy":

_____________________________________________

Some recent claims for the "audible superiority" and "better
soundstage accuracy" of loudspeakers with more-or-less
omni-directional radiation patterns, compared to conventional
loudspeakers with much narrower horizontal directivity patterns, beg
further examination and informed comment. Further, a few of the
definitions and descriptions given for binaural and stereo recording
and reproduction also need to be compared to what well known texts
have to say about the subject.

For example, in one recent posting the author spoke of what he
believed to be the differences between "binaural" and "stereo"
recordings and their reproduction. Unfortunately, much of what the
author said does not appear to agree with what has been published on
the subject within credible books and journals.

With respect to defining the "differences" between binaural and
stereo recording and playback systems, on page 181 of the book
"Hearing - Its Psychology and Physiology", by Stanley S. Stevens,
Ph.D., published by the American Institute of Physics, we find,
"There are two ways of reproducing sounds in true auditory
perspective. One is binaural reproduction, in which there is led to
the observer's ears, by means of earphones, an exact copy of the
sound-waves which would stimulate his two ears if he were listening
directly. We can do this conveniently by picking up the sound with
two microphones, placed in the position of the ears on a man-shaped
dummy, and connecting one earphone to the amplified output of each
microphone. Then, if someone walks around the dummy, talking as he
goes, a person wearing the earphones has a compelling illusion of
someone walking around him. The other method uses two or more
microphones and a corresponding number of loudspeakers, and aims to
reproduce in a second room an exact copy of the pattern of
sound-vibration that exists in the original room." And, "Ideally, an
infinite number of microphones and loudspeakers of infinitesimal
dimensions would be needed to make the reproduction perfect, but, in
practice, as few as two microphone-loudspeaker combinations
(channels) have been found to give fair auditory perspective.
Extensive tests were carried out with two and three channels in
various combinations in order to determine the adequacy of such
methods (Steinberg and Snow). With three-channel reproduction, there
is reasonably good correspondence between the actual position on the
stage and the apparent position on the virtual stage, both as regards
right and left, and front and back. Thus, the system affords depth as
well as angular localization." and, "With two-channel reproduction,
the virtual stage tended to appear wider and less deep than with
three-channel reproduction."

Also, in Howard Tremaine's book, "Audio Encyclopedia", the following
questions and answers appear, beginning on page 82: Question - 2.111:
"What is 3-D sound? - The term applied to three-dimensional or
stereophonic sound." Q - 2.112, 2.112: "What is a monaural sound
system? - A sound system consisting of one source of sound, such as a
radio, using a single loudspeaker for reproduction. It is termed
monophonic." Q - 2.113: "What is a binaural sound system? - A system
consisting of two microphones at the point of pickup, placed in the
same relationship to each other as the ears of a listener. The
microphones are connected to separate amplifier systems and transmit
the program material to the listener through headphones. True
binaural sound cannot be achieved with loudspeakers, only headphones.
When loudspeakers are used it is two channel stereophonic sound."
And, Q - 2.114: "What is a stereophonic sound system? - A system
using two or more microphones with a separate amplifier and
loudspeaker for each microphone channel. With such an arrangement of
equipment, the sound travels from one speaker to the other as the
principals move across the stage. Such a system permits an orchestra
to be reproduced closer to its proper perspective."

While some aspects of these definitions might have been a little
clearer had the authors used slightly different wording, I believe
they adequately describe "binaural reproduction" (through headphones)
Vs "stereo reproduction" through loudspeakers.

The belief held by some that large amounts of time-delayed
reflections from listening room boundaries are beneficial and or
necessary for accurately reproducing the original sound field of an
orchestra by a stereo playback system is simply not true! While
loudspeakers with near-omni directivity can sometimes create the
illusion of the listener being "surrounded by sound", this can hardly
be described as an accurate recreation of the original recorded
soundstage or the "stereo imaging" as it was intended to be heard by
competent recording and mastering engineers (which seldom, if ever,
use omni-directional loudspeakers). Indeed, having maintained close
contacts with several of the top recording and mastering companies in
the U.S. during the past twenty-plus years, I cannot recall a
single one that has used loudspeakers with omni or near-omni
radiation patterns while engineering their products.

(However, it must be admitted that a wide and diffuse sound field,
created by omni or quasi-omni loudspeakers within a typically
reverberant listening room, can appeal to many kinds of listeners -
until they eventually recognize that such a sound field is not
realistic and often becomes tiring after a relatively long listening
session.)

Further, the diffuse spatial qualities produced by loudspeakers with
quasi-omni directivity should never be likened to the spatial
qualities of a "binaural recording" heard through headphones. They
simply are not the same - period! Nor should the diffuse soundfield
created by nearly omni-directional loudspeakers ever be referred to
as being more "accurate" than the "stereo soundstage" attainable
within a good listening room when listening to truly accurate
loudspeakers possessing symmetrical, relatively narrow radiation
patterns in both vertical and horizontal planes.

Anyway, my time limit for internet chatter has been reached for
today. Perhaps, a few others will find time to post their own
references, experiences and opinions regarding the audible
differences between very wide and relatively narrow loudspeaker
directivity patterns and how each impacts upon our perception of
"realism" when reproducing well-recorded music within a typical
audiophile listening room.

Many thanks to John Ongtooguk, Robert Salvi, Thomas Nulla, Stewart
Pinkerton, Paul Macca, et al, for their many cogent and informed
comments.

Best of listening,

John Dunlavy

[Gary Eickmeier/Susan Andrus]

Dunlavy Audio Labs wrote:

> Some recent claims for the "audible superiority" and "better
> soundstage accuracy" of loudspeakers with more-or-less
> omni-directional radiation patterns, compared to conventional
> loudspeakers with much narrower horizontal directivity patterns, beg
> further examination and informed comment. Further, a few of the
> definitions and descriptions given for binaural and stereo recording
> and reproduction also need to be compared to what well known texts
> have to say about the subject.

Who said these quotes? What posts are they from? Is the context not
relevant?

>
> For example, in one recent posting the author spoke of what he
> believed to be the differences between "binaural" and "stereo"
> recordings and their reproduction. Unfortunately, much of what the
> author said does not appear to agree with what has been published on
> the subject within credible books and journals.

What author? What post? Are you making this stuff up?

> Also, in Howard Tremaine's book, "Audio Encyclopedia", the following
> questions and answers appear, beginning on page 82: Question - 2.111:
> "What is 3-D sound? - The term applied to three-dimensional or
> stereophonic sound."

I don't think this holds any more. Some people have taken over the
term "3-D Audio" and made it into a specific technology (different
from ordinary stereophonic sound).

> Q - 2.112, 2.112: "What is a monaural sound
> system? - A sound system consisting of one source of sound, such as a
> radio, using a single loudspeaker for reproduction. It is termed
> monophonic."

This one is an error riot. Monaural means one-eared, and refers to a
system in which the output of a single microphone is connected to a
single earphone worn by the listener. If it were connected to two
earphones, it would be termed "diotic." The suffix "phonic" refers to
loudspeaker reproduction. Monophonic means the output of the single
mike is connected to a single loudspeaker. Stereophonic means two or
more microphones connected to two or more loudspeakers. Calling a
monaural system a monophonic system is the sign of a confused author.

Q - 2.113: "What is a binaural sound system? - A system
> consisting of two microphones at the point of pickup, placed in the
> same relationship to each other as the ears of a listener. The
> microphones are connected to separate amplifier systems and transmit
> the program material to the listener through headphones. True
> binaural sound cannot be achieved with loudspeakers, only headphones.
> When loudspeakers are used it is two channel stereophonic sound."

I'm sure this was written before the crosstalk cancelling systems and
HRTF filters that have led to loudspeaker binaural. The dividing line
is not whether the sound is reproduced on loudspeakers, but whether or
not there is intended to be a signal for each ear. With binaural, each
ear gets the output of only one channel, whether it be from headphones
or loudspeakers; with stereophonic, both ears are allowed to hear both
speakers - and this is not a mistake or error, it is part of the
system.

> And, Q - 2.114: "What is a stereophonic sound system? - A system
> using two or more microphones with a separate amplifier and
> loudspeaker for each microphone channel. With such an arrangement of
> equipment, the sound travels from one speaker to the other as the
> principals move across the stage. Such a system permits an orchestra
> to be reproduced closer to its proper perspective."

Notice that it says "two or more." I take this to mean any field-type
system which is meant to be played back in a normal room (as opposed
to an anechoic chamber), including three channel and surround sound.

> While some aspects of these definitions might have been a little
> clearer had the authors used slightly different wording, I believe
> they adequately describe "binaural reproduction" (through headphones)
> Vs "stereo reproduction" through loudspeakers.

Are you thinking that these are the key points in the definitions,
John? Do you rule out loudspeaker binaural and 3-D sound? Or do you
claim they are field-type systems?

> The belief held by some that large amounts of time-delayed
> reflections from listening room boundaries are beneficial and or
> necessary for accurately reproducing the original sound field of an
> orchestra by a stereo playback system is simply not true! While
> loudspeakers with near-omni directivity can sometimes create the
> illusion of the listener being "surrounded by sound", this can hardly
> be described as an accurate recreation of the original recorded
> soundstage or the "stereo imaging" as it was intended to be heard by
> competent recording and mastering engineers (which seldom, if ever,
> use omni-directional loudspeakers).

Apparently, the many times I have stated that we are not "doing"
accuracy with field-type systems has not even registered with
Mr. Dunlavy - i.e., he does not realize that I said it. Or refuses to
address it.

> (However, it must be admitted that a wide and diffuse sound field,
> created by omni or quasi-omni loudspeakers within a typically
> reverberant listening room, can appeal to many kinds of listeners -
> until they eventually recognize that such a sound field is not
> realistic and often becomes tiring after a relatively long listening
> session.)
>
> Further, the diffuse spatial qualities produced by loudspeakers with
> quasi-omni directivity should never be likened to the spatial
> qualities of a "binaural recording" heard through headphones. They
> simply are not the same - period!

No, of course not. But why do you mention it?

> Nor should the diffuse soundfield
> created by nearly omni-directional loudspeakers ever be referred to
> as being more "accurate" than the "stereo soundstage" attainable
> within a good listening room when listening to truly accurate
> loudspeakers possessing symmetrical, relatively narrow radiation
> patterns in both vertical and horizontal planes.

See what I mean?

>
> Anyway, my time limit for internet chatter has been reached for
> today. Perhaps, a few others will find time to post their own
> references, experiences and opinions regarding the audible
> differences between very wide and relatively narrow loudspeaker
> directivity patterns and how each impacts upon our perception of
> "realism" when reproducing well-recorded music within a typical
> audiophile listening room.
>
> Many thanks to John Ongtooguk, Robert Salvi, Thomas Nulla, Stewart
> Pinkerton, Paul Macca, et al, for their many cogent and informed
> comments.

Hey - you have left my name out, Mr. Dunlavy - I have probably had the
most input on this thread, and caused you the most thought. Probably
just an innocent mistake. I understand! Thanks anyway!

Gary Eickmeier