Perceptual Effects of Room Reflections

[oivavoi]

I became curious about this Robert Greene guy, and searched for his articles on TAS. Indeed, his reviews are some of the best hifi reviews I have read ever. Extremely illuminating. He doesn't content himself with saying if he likes things or not, but tries to explain how things sound, and why they sound that way.

In fact, two of his recent reviews are some of the best introducory texts I've read on reflections and speaker directivity.
Review of the Mur omni speaker: http://www.theabsolutesound.com/art...directional-electrostatic-hybrid-loudspeaker/
Review of the very directional electrostatic Sanders speaker: http://www.theabsolutesound.com/articles/sanders-model-10e-hybrid-electrostatic-loudspeaker/

Ultimately, he seems to prefer quite firmly the highly directional kind of speaker. But he engages in a very honest and illuminating way with the Mur omni, and the omni concept more generally, and the strengths and weaknesses it can have vs very directional speakers.

I share his experience, basically: I like both kinds of speakers! In the future I hope to have two different setups, 0ne directional and one omni, if budget and space allows it.

 

[Jakob1863]

You might like to visit his website:

http://www.regonaudio.com

 

[oivavoi]

You might like to visit his website:

http://www.regonaudio.com

Thanks! Reading it now, lots of interesting stuff.

 

[Scott Borduin]

I became curious about this Robert Greene guy, and searched for his articles on TAS. Indeed, his reviews are some of the best hifi reviews I have read ever. Extremely illuminating. He doesn't content himself with saying if he likes things or not, but tries to explain how things sound, and why they sound that way.

Glad you found him interesting. Greene is both a math professor and an advanced amateur violinist, and so brings a different perspective to reviewing. It is something of a miracle he's been allowed to present his contrarian points of view at TAS for 3 decades or so now. Not only does he depart from the party line on things like cables and electronics and magic BS, he's not shy about his opinions and not tolerant of fools. He also has no icons - he's very critical of Harry Pearson at times, but also skeptical of Floyd Toole's research along some lines.

The regonaudio.com site is a compilation of his writings through the years, and is pretty interesting. For instance, he just completely deconstructs the audiophile obsession with the old 3 mic RCA and Mercury recordings. He makes an interesting case that the 2 channel Blumlein recording setup is pretty much the only theoretically sound construct for stereo recording of an acoustical performance. And so on.

Anyway, he's an original thinker in this space and well worth reading and following.

 

[Wombat]

You might like to visit his website:

http://www.regonaudio.com

I will work my way through the articles. Thanks.

 

[Scott Borduin]

So I just read through the latest version of Toole's book. As with the previous version, a lot of great information and a mandatory read for anyone trying to develop a scientific perspective on audio.

Anyway, there is quite a bit of discussion on the subject of reflections. Toole feels he's been branded as sort of an ambassador for reflections, when in fact it's more complicated than that. It seems from the research that early reflections do tend to improve intelligibility of speech, and help reinforce the timbral signature of instruments. Also, reflections that are uncorrelated at the ears - primarily side reflections - tend to increase "apparent source width", which frequent concert goers will recognize as the sense of bloom around woodwinds, etc. in the orchestra (I have found this to be an elusive quality for stereo systems to reproduce, reflections or not). Reflections from the front and rear, on the other hand, can be detrimental. I think all of this has been discussed before.

Beyond that, he seems to suggest that the desirability of room reflections will depend somewhat on source material - well recorded Classical and other acoustic music typically contain a lot of uncorrelated reflections in the recording itself. I think this partly explains why I am fine with highly directive speakers - virtually all of my critical listening is Classical.

Toole also talks a lot about "envelopment", which I summarize as the sense of being immersed in a diffuse sound field in a performance space. I think striving for envelopment is probably why I like to sit more toward the near field, with wide speaker separation. I think the topic of envelopment perhaps deserves its own post.

 

[garbulky]

So I just read through the latest version of Toole's book. As with the previous version, a lot of great information and a mandatory read for anyone trying to develop a scientific perspective on audio.

Anyway, there is quite a bit of discussion on the subject of reflections. Toole feels he's been branded as sort of an ambassador for reflections, when in fact it's more complicated than that. It seems from the research that early reflections do tend to improve intelligibility of speech, and help reinforce the timbral signature of instruments. Also, reflections that are uncorrelated at the ears - primarily side reflections - tend to increase "apparent source width", which frequent concert goers will recognize as the sense of bloom around woodwinds, etc. in the orchestra (I have found this to be an elusive quality for stereo systems to reproduce, reflections or not). Reflections from the front and rear, on the other hand, can be detrimental. I think all of this has been discussed before.

Beyond that, he seems to suggest that the desirability of room reflections will depend somewhat on source material - well recorded Classical and other acoustic music typically contain a lot of uncorrelated reflections in the recording itself. I think this partly explains why I am fine with highly directive speakers - virtually all of my critical listening is Classical.

Toole also talks a lot about "envelopment", which I summarize as the sense of being immersed in a diffuse sound field in a performance space. I think striving for envelopment is probably why I like to sit more toward the near field, with wide speaker separation. I think the topic of envelopment perhaps deserves its own post.

Nice post! I love this stuff. Melding perception with objective data.
Though I haven't done any measurements I do experiment extensively with hideous looking room treatments to the dismay of my wife. I have a small living room so I guess the reflections are early.

 

[Sal1950]

I do experiment extensively with hideous looking room treatments to the dismay of my wife.

That's a man's job,
To upset the delicate sensibilities of the female persuasion.

 

[Wombat]

That's a man's job,
To upset the delicate sensibilities of the female persuasion.

Have you ever gone to buy a car with your nearest and dearest and all goes well until the color-chart is presented and it doesn't have the right shade of xxxxx?

 

[Fitzcaraldo215]

Glad you found him interesting. Greene is both a math professor and an advanced amateur violinist, and so brings a different perspective to reviewing. It is something of a miracle he's been allowed to present his contrarian points of view at TAS for 3 decades or so now. Not only does he depart from the party line on things like cables and electronics and magic BS, he's not shy about his opinions and not tolerant of fools. He also has no icons - he's very critical of Harry Pearson at times, but also skeptical of Floyd Toole's research along some lines.

The regonaudio.com site is a compilation of his writings through the years, and is pretty interesting. For instance, he just completely deconstructs the audiophile obsession with the old 3 mic RCA and Mercury recordings. He makes an interesting case that the 2 channel Blumlein recording setup is pretty much the only theoretically sound construct for stereo recording of an acoustical performance. And so on.

Anyway, he's an original thinker in this space and well worth reading and following.

I have read Greene over the years, and I participated in his forum for awhile. I was expelled, but not because I was uncivil. I do not believe I was. I was merely trying to explain to him the standards for and errors in his setup procedures for multichannel, a topic he was very much interested in but, surprisingly, totally ignorant of, especially considering his theoretical and technical knowledge in other areas.

Some of his writings are very good. Others, not so good, in my opinion. But, no one is perfect.

I see no huge "audiophile obsession" with 3 channel RCA and Mercury recordings. Yes, some find those recordings in stereo to be wonderful, such as friend Art Lintgen, who praises them frequently in TAS reviews. I have some remastered on SACD, and I am able to compare the 3 vs. 2 channel versions from the same disc, since I have a Mch setup. Not too many audiophiles have that opportunity. I distinctly prefer the 3's, but there are numerous modern, discretely recorded 5.0/.1 channel recordings that are far better. Comments by Kal Rubinson of Stereophile, Andy Quint of TAS, and other friends, all quite agree about the 3's, as well as modern 5.0/.1's. Meanwhile, at least up to then, Greene never had a center channel speaker in his Mch setup. He absolutely did not want to know why that was important, not just for the 3 channel recordings, but for Mch in general.

Being a math professor makes him value pure, exquisite theory very highly. Hence, his obsessional embrace of Blumlein and other coincident pair mike techniques. He worked with Kavi Alexander at Water Lily on numerous recordings using that technique. One was done here with the Philadelphia Orchestra under Sawallisch in the old Academy of Music. Not a single person I know who has heard that orchestra in that hall thinks it is a good recording, though Greene consistently argued it was. He also made an SACD of the (then) Leningrad Philharmonic under Temirkamov with Kavi, where he added synthesized surround channels to Kavi's Blumlein fronts. Friends and I have it. It is terrible in Mch, and not even that great in plain stereo.

Blumlein and other coincident or near-coincident miking is beautiful and elegant in theory, compared to spaced omnis. But, talk to most any classical recording engineer, as I have with a few, and they will tell you they are well aware of it. They may also bend your ear on the many reasons why it fails in practice and why they refuse to use it. That is not even to mention the weird 90 degree speaker layout needed to listen to it properly, when most all other recordings are miked and mixed for the more conventional 60 degree nominal layout. Greene solved this by advocating two listening chairs, one for each angular layout. Just change seats and move more into the near field!

So, good luck with Blumlein, especially with finding those recordings. I have got a whole lot more really excellent, discretely recorded Mch recordings to listen to, myself. And, Blumlein ain't making a big comeback any time soon, I do not believe.

 

[Scott Borduin]

Some of his writings are very good. Others, not so good, in my opinion. But, no one is perfect.

Indeed. Since I wrote that post, I reread Toole's book in it's latest version. I'm not sure I'd have written that post had I read it before, certainly not with the same words

I see no huge "audiophile obsession" with 3 channel RCA and Mercury recordings. Yes, some find those recordings in stereo to be wonderful, such as friend Art Lintgen, who praises them frequently in TAS reviews. I have some remastered on SACD, and I am able to compare the 3 vs. 2 channel versions from the same disc, since I have a Mch setup. Not too many audiophiles have that opportunity. I distinctly prefer the 3's, but there are numerous modern, discretely recorded 5.0/.1 channel recordings that are far better. Comments by Kal Rubinson of Stereophile, Andy Quint of TAS, and other friends, all quite agree about the 3's, as well as modern 5.0/.1's. Meanwhile, at least up to then, Greene never had a center channel speaker in his Mch setup. He absolutely did not want to know why that was important, not just for the 3 channel recordings, but for Mch in general.

Back in the day, I was a big TAS reader, and the 3 channel RCAs and Mercs were Harry Pearson's references (talk about the circle of confusion!). For a time, original era LP pressings were going for 100s of dollars. I never found most of them particularly convincing - compressed and distorted at loud levels, often overly bright. More comments on Mch below.

Being a math professor makes him value pure, exquisite theory very highly. Hence, his obsessional embrace of Blumlein and other coincident pair mike techniques.

Yes. REG would not like to hear this, but he's a much better theoretician than scientist. Toole, for example, runs rings around him as a scientific thinker and also as a practical guide to improving your own experience. But REG has been one of the few voices in the high end consistently preaching the primacy of frequency response, loudspeaker response and radiation pattern, etc. His theoretical background keeps him from being seduced by audiophile magic thinking, and brings an analytical bias to subjective experience.

Blumlein and other coincident or near-coincident miking is beautiful and elegant in theory, compared to spaced omnis. But, talk to most any classical recording engineer, as I have with a few, and they will tell you they are well aware of it. They may also bend your ear on the many reasons why it fails in practice and why they refuse to use it. That is not even to mention the weird 90 degree speaker layout needed to listen to it properly, when most all other recordings are miked and mixed for the more conventional 60 degree nominal layout. Greene solved this by advocating two listening chairs, one for each angular layout. Just change seats and move more into the near field!

So, good luck with Blumlein, especially with finding those recordings. I have got a whole lot more really excellent, discretely recorded Mch recordings to listen to, myself. And, Blumlein ain't making a big comeback any time soon, I do not believe.

The basic problem with Blumlein is that it's stereo. "Theoretically perfect stereo" is an oxymoron, given the arbitrary and fundamentally limiting nature of two channel reproduction of a 3D sound field. If recording engineers find it necessary to deviate from the theoretical ideal in order to partially overcome the perceptual deficiencies of stereo, as they obviously do, well then god bless them. The basic mental model shift I've carried away from reading Toole and another recent AES book on immersive sound is that the stereo paradigm is badly in need of replacement.

I chased the multichannel thing for many years, through a couple of generations of Meridian gear. Better than stereo in some ways, particularly the addition of the center channel with Meridian version of Trifield processing. True 5.x multichannel, though, never exactly lived up to it's promise for me. I think there might be some simple reasons for that, which I'm mentally organizing for another post. It would be great for you and other Mch veterans to chime in when I get that post up.

 

[Kal Rubinson]

Back in the day, I was a big TAS reader, and the 3 channel RCAs and Mercs were Harry Pearson's references (talk about the circle of confusion!). For a time, original era LP pressings were going for 100s of dollars. I never found most of them particularly convincing - compressed and distorted at loud levels, often overly bright.

AFAIK, he did not listen to them in 3-channels, but in stereo.

I chased the multichannel thing for many years, through a couple of generations of Meridian gear. Better than stereo in some ways, particularly the addition of the center channel with Meridian version of Trifield processing. True 5.x multichannel, though, never exactly lived up to it's promise for me. I think there might be some simple reasons for that, which I'm mentally organizing for another post. It would be great for you and other Mch veterans to chime in when I get that post up.

Looking forward to that.

 

[Fitzcaraldo215]

Indeed. Since I wrote that post, I reread Toole's book in it's latest version. I'm not sure I'd have written that post had I read it before, certainly not with the same words



Back in the day, I was a big TAS reader, and the 3 channel RCAs and Mercs were Harry Pearson's references (talk about the circle of confusion!). For a time, original era LP pressings were going for 100s of dollars. I never found most of them particularly convincing - compressed and distorted at loud levels, often overly bright. More comments on Mch below.



Yes. REG would not like to hear this, but he's a much better theoretician than scientist. Toole, for example, runs rings around him as a scientific thinker and also as a practical guide to improving your own experience. But REG has been one of the few voices in the high end consistently preaching the primacy of frequency response, loudspeaker response and radiation pattern, etc. His theoretical background keeps him from being seduced by audiophile magic thinking, and brings an analytical bias to subjective experience.



The basic problem with Blumlein is that it's stereo. "Theoretically perfect stereo" is an oxymoron, given the arbitrary and fundamentally limiting nature of two channel reproduction of a 3D sound field. If recording engineers find it necessary to deviate from the theoretical ideal in order to partially overcome the perceptual deficiencies of stereo, as they obviously do, well then god bless them. The basic mental model shift I've carried away from reading Toole and another recent AES book on immersive sound is that the stereo paradigm is badly in need of replacement.

I chased the multichannel thing for many years, through a couple of generations of Meridian gear. Better than stereo in some ways, particularly the addition of the center channel with Meridian version of Trifield processing. True 5.x multichannel, though, never exactly lived up to it's promise for me. I think there might be some simple reasons for that, which I'm mentally organizing for another post. It would be great for you and other Mch veterans to chime in when I get that post up.

Great, Scott! (Pardon the pun.)

I, and I am sure Kal, would love to discuss Mch further with you and others. Yes, like Toole, we agree that the 2 channel stereo paradigm has served us well for many decades, as mono did before that. But, it is far from the end of the road in terms of improved sound quality if we wish to get closer to the ideal of providing a plausible image of live music performance in the hall. Kal and I, among at least a few others, believe that a breakthrough has been achieved in the last decade or more for Mch music, principally via discrete recordings on the Mch SACD, and bolstered by parallel, compatible developments in Mch home theater technology and equipment.

I do not want to appear totally dismissive or antagonistic to REG. He was, for example, an early proponent of DSP room EQ, another breakthrough Kal and I find "essential" in REG's word. Also, I found his essay, as follows, among some others, to be generally illuminating and excellent:

http://www.regonaudio.com/Records and Reality.html

 

[Sal1950]

principally via discrete recordings on the Mch SACD

Sadly under utilized is the BluRay media which offers the ability to add more dircrete channels for doing immersive recordings, etc.
SACD was a great medium in it's day, offering backward compat with CD, etc.
But time has moved on and SACD should be put to bed. IMO

 

[Kal Rubinson]

Sadly under utilized is the BluRay media which offers the ability to add more dircrete channels for doing immersive recordings, etc.
SACD was a great medium in it's day, offering backward compat with CD, etc.
But time has moved on and SACD should be put to bed. IMO

I agree with you in principle. However, I really doubt that, until there is a vast advance in engineering that will allow room surfaces to be an array of transducers, that music reproduction will really move beyond 5.1/7.1 channels. Another possibility is the advance in immersive audio by DSP that will allow a limited number of transducers to simulate the activity of multiple sources.

 

[Fitzcaraldo215]

Sadly under utilized is the BluRay media which offers the ability to add more dircrete channels for doing immersive recordings, etc.
SACD was a great medium in it's day, offering backward compat with CD, etc.
But time has moved on and SACD should be put to bed. IMO

Yes, BD is used for 7.1 audio, even for "3D" music with even more channels than that. But, even with videos, there is surprisingly little comparatively in 7.1 vs. 5.1. I do have a 7.1 system and I have listened to music and watched videos with it. My opinion is that I wasted money on 7.1 vs. 5.1.

Higher channel counts might add to the effect or potential realism of the result, but the law of diminishing returns always prevails. 7.1 simply does not add significantly over 5.1, unlike stereo vs. mono. And, the demos I have heard of Auro 3D are not breathtaking compared to 5.1. So, those who discount today's 5.1 Mch because we "need" even more channels for music will be waiting for a very long time to see more than a handful of music releases. If there is ever a mature music market with significant numbers of available releases beyond 5.1, I will have been long dead. So, I ain't gonna wait, and 5.1 is too much better than 2.0 now to do so.

It is Mark Twainism about SACD among many, exaggerated rumors of death. Or, even worse now, death wishes. I understand that it can appear to be dead to myopic, ego-centric rock 'n rollers in terms of available, especially newer, releases. And, frankly, Mch does not do much for studio-mixed pop music except introduce the gimmick of panning performers to back channels. Take my word for it, that is not at all what Mch does for classical music. A niche of classical music lovers realizes that.

But, why do you want to put it death? Is it bothering you that it pleases some of us? What is the problem? It takes nothing whatsoever away from the the music you prefer in whatever channel layout or disc format you wish. So, time has moved on, but you wish to kill the only successful source of Mch music, a newer set of ideas? Hey, if your choice is to stick with compressed pop on CD, streaming and downloads, I have no objection. Why do you need to object to what I like with a death wish?

 

[Sal1950]

I agree with you in principle. However, I really doubt that, until there is a vast advance in engineering that will allow room surfaces to be an array of transducers, that music reproduction will really move beyond 5.1/7.1 channels. Another possibility is the advance in immersive audio by DSP that will allow a limited number of transducers to simulate the activity of multiple sources.

Pity the poor audiophile, he's been fighting the "wife acceptance factor" since the introduction of separate components, let alone stereo. LOL
It is a shame we yearned for so many years to have really good fully discrete multich technology available, and now that we do, so few care or are willing to supply the recorded media to take advantage of it.

 

[Sal1950]

But, why do you want to put it death? Is it bothering you that it pleases some of us? What is the problem? It takes nothing whatsoever away from the the music you prefer in whatever channel layout or disc format you wish. So, time has moved on, but you wish to kill the only successful source of Mch music, a newer set of ideas? Hey, if your choice is to stick with compressed pop on CD, streaming and downloads, I have no objection. Why do you need to object to what I like with a death wish?

My my, aren't we touchy about the little obsolete piece of optical disc media. Yes, time has moved on, but feel free to also join the vinyl revival gang, get yourself some SQ, QS, and CD4 LP's and really go retro with your mch sources. Maybe you could launch a whole renaissance in quad vinyl gear, it would be great for the industry.
How kool to get some Rice Krispies mixed with your 4 channel sound.

And what did any of that have to do with throwing mud at anyone's musical genre preferences?
You are a testy ole codger aren't ya.

 

[Wombat]

Yes, BD is used for 7.1 audio, even for "3D" music with even more channels than that. But, even with videos, there is surprisingly little comparatively in 7.1 vs. 5.1. I do have a 7.1 system and I have listened to music and watched videos with it. My opinion is that I wasted money on 7.1 vs. 5.1.

Higher channel counts might add to the effect or potential realism of the result, but the law of diminishing returns always prevails. 7.1 simply does not add significantly over 5.1, unlike stereo vs. mono. And, the demos I have heard of Auro 3D are not breathtaking compared to 5.1. So, those who discount today's 5.1 Mch because we "need" even more channels for music will be waiting for a very long time to see more than a handful of music releases. If there is ever a mature music market with significant numbers of available releases beyond 5.1, I will have been long dead. So, I ain't gonna wait, and 5.1 is too much better than 2.0 now to do so.

It is Mark Twainism about SACD among many, exaggerated rumors of death. Or, even worse now, death wishes. I understand that it can appear to be dead to myopic, ego-centric rock 'n rollers in terms of available, especially newer, releases. And, frankly, Mch does not do much for studio-mixed pop music except introduce the gimmick of panning performers to back channels. Take my word for it, that is not at all what Mch does for classical music. A niche of classical music lovers realizes that.

But, why do you want to put it death? Is it bothering you that it pleases some of us? What is the problem? It takes nothing whatsoever away from the the music you prefer in whatever channel layout or disc format you wish. So, time has moved on, but you wish to kill the only successful source of Mch music, a newer set of ideas? Hey, if your choice is to stick with compressed pop on CD, streaming and downloads, I have no objection. Why do you need to object to what I like with a death wish?

"If you prefer to stick with compressed pop on CD". What a snobbish(Classical?) rash generalisation. Not all CDs are compressed any more than other formats.
My impression is that Sal1950 interests I are much wider than' pop', as are mine. I have no issue with pop as it is presented to its audience. It is also offered on higher Q media. I get the impression that you can't distinguish between the many music genres outside of your chosen ones or relate to other musical preferences..

 

[Kal Rubinson]

Pity the poor audiophile, he's been fighting the "wife acceptance factor" since the introduction of separate components, let alone stereo. LOL
It is a shame we yearned for so many years to have really good fully discrete multich technology available, and now that we do, so few care or are willing to supply the recorded media to take advantage of it.

It is not a matter of WAF.

Most people in this world listen with earphones or to whatever is built into their TVs. Tiny pod speakers, too. For all the multichannel AVRs and home theater kits that are sold, few are installed properly and, probably, fewer are ever used for music. ATMOS? That hasn't changed anything since, again, few are installed properly and, probably, fewer are ever used for music. Audiophiles are a minute niche of the market and many (most?) are traditionalists who will not consider going beyond 2 channels, turntables and tubes.

The exception to all this are the very, very few who appreciate the value that multichannel can bring to music enjoyment and, of those, some would embrace expansion to "immersive" systems if it was worth the bother. But they, we, are not a significant number, have no leverage in the mainstream and, because of that, no significant recorded media exist. Why would I bother to pay for, install and maintain a 11.2 channel system when there's nothing to play on it?