Announcement. AES Presentation on “What is Accuracy” by our very own member @j_j_ or James D. (jj) Johnston - Chief Scientist - Immersion Networks

[Sal1950]

Most? No you don’t. Most never existed on Discrete Quad. And most quad mixes were an after thought.

I guess your not aware of Vocalion-Rhino-Quadio reissues of the classic quads on 24-192 BluRays
Another batch of 4 is set for release this month
Most of the Pink Floyd catalog have been reissued in 5.1 or Atmos and included copies of the original quad issue
if the existed. Alan Parsons original quad mix of Dark Side of the Moon is one of my favorite.
You do have to know a little about what your talking about before running your mouth.

 

[Cbdb2]

Not originals but the ones I've heard are very close.

New SW classic album remixes available now - Steven Wilson

Steven’s new stereo / 5.1 surround sound remixes of both Yes “Close to the Edge”, and XTC “Nonsuch” are now in stock and shipping from Headphone Dust. Both come in a choice of Blu-Ray / CD or DVDA / CD editions, each containing new stereo and 5.1 mixes, and the original stereo mix, all flat...

stevenwilsonhq.com

 

[Justdafactsmaam]

I guess your not aware of Vocalion-Rhino-Quadio reissues of the classic quads on 24-192 BluRays
Another batch of 4 is set for release this month

I’m quite aware of them. 4 you say? 4!?!? You were claiming MOST of the entire span of commercially recorded music was available in quad or “better” your words “I got most of that on discrete quad or better, no problem.”

Might want to check your math. You don’t have most.

Most of the Pink Floyd catalog have been reissued in 5.1 or Atmos and included copies of the original quad issue
if the existed.

The remixes are not true to the originals. The original quad mixes are documented as not being to the liking of the artists. You really don’t have much to listen to if you are committed to accuracy to the original recordings and artists’ intent.

Alan Parsons original quad mix of Dark Side of the Moon is one of my favorite.

I’m happy you find it fun and engaging. But it ain’t high fidelity to the original recording. It was an afterthought that the band did not care for. But it’s ok to like it even if it bears little or no resemblance to the artists’ original intention.

You do have to know a little about what your talking about before running your mouth.

Maybe more than just a little. Just a little doesn’t seem to be serving you here.

 

[AdamG]

Everyone dial down the aggression and please treat each other with respect and dignity. It’s not a big ask and if you don’t you will ruin my very calm and relaxing Sunday morning. Take a break if you need. It’s just a Forum. I love the passion and energy in this conversation so let’s go with that instead. We all can learn something new everyday. OK, well most of us mortals can….

Happy Sunday Shipmates.

 

[MattHooper]

I think he is referring to the work behind the 2nd paper here in this collection of 1934 articles. They had done the work in 1933.

https://www.aes.org/aeshc/docs/bell.labs/auditoryperspective.pdf

Auditory perspective- Physical factors starting on page 6 of this pdf.

Short summary is they used tests where people listened to microphones linked to speakers with 2 channels or 3 channels (a center). It found good correspondence with reality using 3 channels, but distortion of spatial positioning with 2 channels or with 2 channels having a mono'd center speaker added.
They had started with many microphone across a soundstage fed to many speakers across a listening room. Obviously not terribly practical. They found most of that benefit was preserved with 3 channel recording/playback, but not with 2 channels.

First, thanks very much for that link!

I went through a good portion of the section you cited. What I took away (hopefully correctly) among the results, was that 2 channel reproduction tended to produce a more recessed sound, where the listeners marked it as the apparent sound source occurring at greater depth. The 3 channel sound with the center channel produced impressions with less center depth, which were more accurate to the actual position of the real sound reference. (Though the paper concludes neither 2 nor 3 channel is sufficient to fully reproduce all the real positional cues accurately).

That was interesting especially as it seems to track pretty well with my own experience comparing stereo vs L/C/R in my system. The stereo tends to have the greater feeling of depth. And to that end, while there are certain other advantages to having the center, one advantage to the 2 channel could be a more convincing sense of space behind the plane of the front loudspeakers. So for instance if you are playing an orchestral recording, without a center channel those distant trumpet, tympani, percussion et may not be as accurately reproduced in terms of "the recording" but the extended sense of depth could be more "accurate" in recreating the sensation of depth to those instruments vs the others. In other words, anything that expands the apparent scale and depth of the orchestra is going to be a bit more like the real thing. I dunno, but that seems to track pretty well with what I hear comparing two channel to L/C/R.

It seems one note in the conclusions leaves room for this prospect:


6. The application of acoustic perspective to orchestral reproduc-
tion in large auditoriums gives more satisfactory performance than
probably would be suggested by the foregoing discussions. The
instruments near the front are localized by every one near their cor-
rect positions. In the ordinary orchestral arrangement, the rear
instruments will be displaced in the reproduction depending upon the
listener’s position, but the important aspect is that every auditor
hears differing sounds from differing places on the stage and is not
particularly critical of the exact apparent positions of the sounds so
long as he receives a spatial impression. Consequently 2-channel
reproduction of orchestral music gives good satisfaction, and the
difference between it and 3-channel reproduction for music probably
is less than for speech reproduction or the reproduction of sounds
from moving source

 

[Blumlein 88]

First, thanks very much for that link!

I went through a good portion of the section you cited. What I took away (hopefully correctly) among the results, was that 2 channel reproduction tended to produce a more recessed sound, where the listeners marked it as the apparent sound source occurring at greater depth. The 3 channel sound with the center channel produced impressions with less center depth, which were more accurate to the actual position of the real sound reference. (Though the paper concludes neither 2 nor 3 channel is sufficient to fully reproduce all the real positional cues accurately).

That was interesting especially as it seems to track pretty well with my own experience comparing stereo vs L/C/R in my system. The stereo tends to have the greater feeling of depth. And to that end, while there are certain other advantages to having the center, one advantage to the 2 channel could be a more convincing sense of space behind the plane of the front loudspeakers. So for instance if you are playing an orchestral recording, without a center channel those distant trumpet, tympani, percussion et may not be as accurately reproduced in terms of "the recording" but the extended sense of depth could be more "accurate" in recreating the sensation of depth to those instruments vs the others. In other words, anything that expands the apparent scale and depth of the orchestra is going to be a bit more like the real thing. I dunno, but that seems to track pretty well with what I hear comparing two channel to L/C/R.

It seems one note in the conclusions leaves room for this prospect:


6. The application of acoustic perspective to orchestral reproduc-
tion in large auditoriums gives more satisfactory performance than
probably would be suggested by the foregoing discussions. The
instruments near the front are localized by every one near their cor-
rect positions. In the ordinary orchestral arrangement, the rear
instruments will be displaced in the reproduction depending upon the
listener’s position, but the important aspect is that every auditor
hears differing sounds from differing places on the stage and is not
particularly critical of the exact apparent positions of the sounds so
long as he receives a spatial impression. Consequently 2-channel
reproduction of orchestral music gives good satisfaction, and the
difference between it and 3-channel reproduction for music probably
is less than for speech reproduction or the reproduction of sounds
from moving source

That fits with J_J's comment that this applies to moderate field (not far field and not near field) distance cues.

I do wonder how that all would work out with various microphones techniques. In the old work they used condenser mikes which were omnidirectional (or close to it) with wide spacing. How would it work with say an ORTF pair and some sort of center mike? I have done some mid-side recordings which are not spaced and they do work pretty well if you extract the mid part for the center channel. Doing well means a pleasant recording, but I haven't with any rigor tried to ascertain if that is more accurate in terms of distance cues.

There are actually plenty of papers on various 5 or 7 channel surround miking for accuracy or sometimes preference. They often are contradictory about which method is best. My take away from it is for a general pleasant sound MCH makes it less critical for a pleasant illusion whether it is accurate or not.

 

[Sal1950]

I do wonder how that all would work out with various microphones techniques. In the old work they used condenser mikes which were omnidirectional (or close to it) with wide spacing. How would it work with say an ORTF pair and some sort of center mike? I have done some mid-side recordings which are not spaced and they do work pretty well if you extract the mid part for the center channel. Doing well means a pleasant recording, but I haven't with any rigor tried to ascertain if that is more accurate in terms of distance cues.

There in are the big questions.
Except in rare release instances we have no idea of the microphone techniques, let alone mic types or positioning.
And much of today orchestra recordings are done with techniques far removed from 2 mic purist types.
Talk about a circle of confusion, as a non-classical listener, from the outside this all looks like a huge guessing game.
How do we fold the knowledge gained from those listening results into just about anything being played now?
Just sayin,

 

[MattHooper]

Here's another question concerning imaging/localization:

As I've mentioned before, I want as much density and palpability to the sonic images as I can get from 2 channel. And my biggest gripe is how, due to the various deficits often pointed out in stereo, the phantom stereo images tend to have a phasey, see-through "not really there" quality vs the very dense acoustic power of a real voice or instrument occupying the same space.

I can play with two channel vs L/C/R either by playing music on my surround system (and just flipping between stereo and strictly L/C/R output), or I sometimes add the center channel to my 2 channel system, and flip back and forth between just stereo and with the center channel in play.

While I lose some depth with the center channel, I gain a sense of image solidity and palpability particularly for centered images. Which makes sense. A centered vocal is no longer a gauzy phantom image as with stereo, but it's now an actual sound source, coming from a speaker in that position.

In trying to get the best of both worlds, the depth and precision of imaging from my 2 channel system with more of that image density, I now often use a curved diffusor placed on my center channel (or in front of it). Which places that diffusor between my stereo speakers and several feet behind. The most obvious effect this seems to have, aside from slight changes in timbre/tone, is that images, especially towards the center, seem to solidify and become more dense - very much like the effect of when I engage the actual center channel! So a vocalist for instance now sounds more dense and focused and solid. Not quite to the degree of using a center, but certainly better than without the diffusor when playing stereo.

If my perception is real and not pure imagination, I wonder what explains this.

One of my intuitions goes: I've placed a large reflective object, the diffusor, between the speakers. So now the diffusor has added some directional energy to the reflections - I'm hearing sound bouncing off that diffusor, coming from that direction, and so it's creating something a bit like a center channel effect.

Alternatively, diffusors aren't supposed to produce discrete reflections but diffuse them, so what is instead happening is just a spectral/reflection/distortion balance in the overall sound, which may end up having a similar perceptual effect in the apparent image density.

Anything to those hunches?

 

[j_j]

There in are the big questions.
Except in rare release instances we have no idea of the microphone techniques, let alone mic types or positioning.

And, very importantly,how the miked material, however it was captured, is actually inserted into the final master.

I have much to say and demonstrate on that point, but I am presently unable to do so.

 

[Sal1950]

Nor originals but the ones I've heard are very close.

New SW classic album remixes available now - Steven Wilson

Steven’s new stereo / 5.1 surround sound remixes of both Yes “Close to the Edge”, and XTC “Nonsuch” are now in stock and shipping from Headphone Dust. Both come in a choice of Blu-Ray / CD or DVDA / CD editions, each containing new stereo and 5.1 mixes, and the original stereo mix, all flat...

stevenwilsonhq.com

Ah, Steven Wilson's mixing-mastering genius has brought us so many beautiful remasters of the rock classics.
Along with tons of original recordings of his own band, solo releases, and others.
So much of it in 2ch and the various multich formats.
He's been a true gift to the audiophile community!

Anything to those hunches?

IMO, Absolutely! Anything that would change the reverberate properties of your room will have an effect on your image perception.
It's my opinion that the High End media makes way too big an issue of "imaging". Just about anything you do with your rig is going to effect it.
Move the speakers, in-out, up-down, apart-together, angle to, distance from, on and on changes it some.
When we move beyond tonality, timing and the rest, we should probably feel free to go for what we prefer for image focus, there is no standard to judge by.
One of the few times I thought we could come close was with some of Mario,s Play Classic's recordings where he detailed just about everything about the setups.
It was fun and interesting but applicable only to his stuff.

 

[youngho]

@j_j
1. You mentioned a codec issue where the same issue caused 70% to observe pre-echo (nearly all of the people who worked in studios) and 30% to observe messed-up imaging (those who have done a lot of work in live sound). Can you please comment further on characteristics of these groups? I was reminded about how musicians and audio professionals seem to be more sensitive to lateral reflections, but I don't assume any correlation to what you're describing.
2. In your discussion about transducers, you briefly alluded to the reflections off the back of the room, and your slide indicated that these rear wall reflections would be similar to the on-axis sound. Does that lack of spectral or timbral distortion change the perceptual significance of these rear wall reflections, compared with lateral, floor, and ceiling reflections that would usually expected to differ with frequency from the on-axis response?

Regarding the second, I'm wondering about a comment from Griesinger: "t is well known that a prompt early reflection can augment speech and musical instruments…Often in a room where localization and proximity is poor a seat in the very last row, up against the back wall, will sound much better…In practice I had found that your ears had to be within two and a half feet of the wall for the trick to work…The results showed that a reflection at 5ms which was 6dB less strong than the direct sound did augment the loudness and the localizability of a source without detrimental effects on timbre…” Also, Joachim Gerhard (previously of Audio Physic) had proposed listener placement <1m of the wall behind him/her, arguing that “From experience that this reflection is not so objectionable for phantom image perception.”

It seemed to me, as a naive low-level student of these phenomenon, that these similar thresholds seem to align with the transition from fusion to localization dominance and discrimination suppression, so perhaps arrival of a similar spectrum reflection more than 0.63-1 ms or so (beyond which loudness compresses within the ERBs) up to about 5 ms or so (beyond which fusion seems to fail for most listeners for clicks, though speech or especially music would be longer) could be perceptually "beneficial" through:
A. Loudness enhancement as noted, since the very early rear wall reflection would be perceptually "added" to the direct signal, perhaps with comb filtering but otherwise nearly identical. The ERB loudness compression at around 1 ms would emphasize the leading edges of the direct signal, while the rear wall reflection would arrive early enough to avoid adversely affecting localization?
B. The very early nature of the rear wall reflections could relatively preserve envelopes without scrambling them, again not adversely affecting localization?
C. Depending on listening proximity to the rear wall and system setup, could head shadowing effects potentially enhance localization by reducing interaural cross-talk, i.e. could the head itself when in close enough proximity to the rear wall block to some degree the signal from one loudspeaker from reflecting off the rear wall and reaching the other ear? I'm assuming that would be expected to enhance localization.

Thanks in advance for your time and consideration,

Young-Ho

[edit: italics removed]

 

[j_j]

@j_j
1. You mentioned a codec issue where the same issue caused 70% to observe pre-echo (nearly all of the people who worked in studios) and 30% to observe messed-up imaging (those who have done a lot of work in live sound). Can you please comment further on characteristics of these groups? I was reminded about how musicians and audio professionals seem to be more sensitive to lateral reflections, but I don't assume any correlation to what you're describing.
2. In your discussion about transducers, you briefly alluded to the reflections off the back of the room, and your slide indicated that these rear wall reflections would be similar to the on-axis sound. Does that lack of spectral or timbral distortion change the perceptual significance of these rear wall reflections, compared with lateral, floor, and ceiling reflections that would usually expected to differ with frequency from the on-axis response?

Regarding the second, I'm wondering about a comment from Griesinger: "t is well known that a prompt early reflection can augment speech and musical instruments…Often in a room where localization and proximity is poor a seat in the very last row, up against the back wall, will sound much better…In practice I had found that your ears had to be within two and a half feet of the wall for the trick to work…The results showed that a reflection at 5ms which was 6dB less strong than the direct sound did augment the loudness and the localizability of a source without detrimental effects on timbre…” Also, Joachim Gerhard (previously of Audio Physic) had proposed listener placement <1m of the wall behind him/her, arguing that “From experience that this reflection is not so objectionable for phantom image perception.”

It seemed to me, as a naive low-level student of these phenomenon, that these similar thresholds seem to align with the transition from fusion to localization dominance and discrimination suppression, so perhaps arrival of a similar spectrum reflection more than 0.63-1 ms or so (beyond which loudness compresses within the ERBs) up to about 5 ms or so (beyond which fusion seems to fail for most listeners for clicks, though speech or especially music would be longer) could be perceptually "beneficial" through:
A. Loudness enhancement as noted, since the very early rear wall reflection would be perceptually "added" to the direct signal, perhaps with comb filtering but otherwise nearly identical. The ERB loudness compression at around 1 ms would emphasize the leading edges of the direct signal, while the rear wall reflection would arrive early enough to avoid adversely affecting localization?
B. The very early nature of the rear wall reflections could relatively preserve envelopes without scrambling them, again not adversely affecting localization?
C. Depending on listening proximity to the rear wall and system setup, could head shadowing effects potentially enhance localization by reducing interaural cross-talk, i.e. could the head itself when in close enough proximity to the rear wall block to some degree the signal from one loudspeaker from reflecting off the rear wall and reaching the other ear? I'm assuming that would be expected to enhance localization.

Thanks in advance for your time and consideration,

Young-Ho

I believe you're mildly mistaken on the "back of the room" comment. They most certainly affect sensation, but I don't think "back of the room is the same" was my point, rather that delayed reflections like that can mess up articulation.

I'm not in agreement with the "early reflections" crowd, I think, rather, using a proper time and amplitude pan is an entire superior approach, of course, you can't fold that down to mono so nobody does it. (yes,there are better ways to make mono, please,than fold-down) If you think about the time structure of those "early reflections" they have a striking similarity to actual time domain panning, yes?

The rest of your questions are not well suited to the 3 more minutes I have before I head out for dinner, sorry. I don't quite come to your conclusion, but then again, I think you're heading in a reasonable direction.

 

[youngho]

I believe you're mildly mistaken on the "back of the room" comment. They most certainly affect sensation, but I don't think "back of the room is the same" was my point, rather that delayed reflections like that can mess up articulation.

I'm not in agreement with the "early reflections" crowd, I think, rather, using a proper time and amplitude pan is an entire superior approach, of course, you can't fold that down to mono so nobody does it. (yes,there are better ways to make mono, please,than fold-down) If you think about the time structure of those "early reflections" they have a striking similarity to actual time domain panning, yes?

The rest of your questions are not well suited to the 3 more minutes I have before I head out for dinner, sorry. I don't quite come to your conclusion, but then again, I think you're heading in a reasonable direction.

Thank you--I was a little confused on this topic in your presentation, since the slide seemed relevant for a listener with their back to the rear wall, while your passing comment in the talk seemed to indicate what you were observing as the speaker facing the rear wall. I think I understand about the "early reflections" in general, but I'm still wondering whether in some cases the rear wall reflection could be considered as perceptually distinct from others due to direction (I'm thinking about effects front-back reversal or confusion, also not "enhancing" lateralization or contributing to ASW) and probably maximal similarity to on-axis sound compared with any other early reflection.

Would appreciate any other thoughts you have in any available time! Very helpful for my learning...

 

[youngho]

@j_j

Also, mention in Stereophile @Jim Austin
https://www.stereophile.com/content/assessing-sonic-illusions

 

[Cbdb2]

@j_j

Also, mention in Stereophile @Jim Austin
https://www.stereophile.com/content/assessing-sonic-illusions.

That is well put. I say an album is to a concert what a film is to a play. A recording should use any technology that helps the artist express the art. Would you be happy to watch movies that are just unedited single camera single shot of a play? Trying to get "live" sound at home would often be trying to get bad sound at home.