Is Toole and Olive's Spinorama model incomplete and limited?

[Thomas_A]

This sounds to me like you are anticipating a perceptual synthesis of the two venues, the recording venue and the playback room, such that the playback room is in effect "a lounge with an opening to the venue of the musical event", presumably the cues of BOTH rooms being in play perceptually at the listening position.

In my opinion if the venue cues on the recording are perceptually dominant, you don't really get a "synthesis" of the two venues; instead you perceive the one and not the other. I realize this is somewhat counter-intuitive, and I don't have any directly applicable examples, but let me offer an example from a different area of psychoacoustics:

I assume you are familiar with the "Yanni vs Laurel" recording? If not, it's easy to Google.

Regardless of whether you perceive "Yanni" or "Laurel", BOTH SETS OF CUES are present! Your ear/brain system selects one set of cues as being the dominant set, and largely or entirely suppresses your awareness of the other set. I think something similar happens in the playback room, in situations where the venue acoustics in the recording are selected by the ear/brain system as being the more plausible set of acoustic environment cues.

It must be a synthesis. Otherwise there would be no audible difference between the anechoic room and the livingroom.

 

[Duke]

The floor reflex is debated. Toole suspects that, for evolutionary reasons, floor reflections do not affect the coloration of direct sound.
For me, there is possibly no coloration of the direct sound of the floor reflex via image shift according to the summation location principle in the vertical plane.

I agree that the floor bounce is perceptually fairly benign. It has little effect on imaging, and its theoretical detrimental effect on tonality is imo offset by the ceiling bounce, which is happening at a different frequency so the floor and ceiling bounces tend to fill one another in. If you go outdoors and talk to someone the floor bounce dip is still there but it is not filled in by the ceiling bounce (nor any other reflections significant), and so your voices will sound thinner outdoors. Most of us don't notice this because our ears have already adapted to their acoustic environment, but if you focus on it you can hear it.

It must emphasize that the spinorama of today has been a giant step towards a more objective description of box speakers in rooms.

Agreed!

It must be a synthesis. Otherwise there would be no audible difference between the anechoic room and the livingroom.

Could you elaborate? I don't want to guess at what you mean before replying.

 

[Inner Space]

Toole suspects that, for evolutionary reasons, floor reflections do not affect the coloration of direct sound.

A minor point, but this is implausible. Human hearing in its current iteration has likely evolved over the last half-million years, itself driven by the evolution of articulate and syntactical language since then. People have lived with flat, reflective floors for at best a few hundred years, and many still don't. Not nearly enough time for an evolutionary effect.

 

[Thomas_A]

Could you elaborate? I don't want to guess at what you mean before replying.

If you are placing a pair of speakers in an anechoic room, you will effectively remove the room reflections, and you will only hear what is on the recording including the venue reflections. Placing the same speakers in a normal room will add reflections from the room. If your brain choose to hear the reflections in the recording and filtering out what is in the room, you would hear the same sound in both situations. But that is not true. Anechoic stereo listening tend almost be headphone-like with cross-feed with sound "in your head". Not so in a normally reflective room.

 

[Duke]

If you are placing a pair of speakers in an anechoic room, you will effectively remove the room reflections, and you will only hear what is on the recording including the venue reflections. Placing the same speakers in a normal room will add reflections from the room. If your brain choose to hear the reflections in the recording and filtering out what is in the room, you would hear the same sound in both situations. But that is not true. Anechoic stereo listening tend almost be headphone-like with cross-feed with sound "in your head". Not so in a normally reflective room.

Thanks for clarifying.

The in-room reflections are the CARRIERS for the reverberation tails on the recording, and therefore can convey a sense of IMMERSION in the acoustic space of the recording because they arrive from all around, assuming the venue cues on the recording are the perceptually dominant package of cues.

The anechoic case you mentioned is a completely different animal, wherein ALL of the venue cues arrive ONLY from the direction of the loudspeakers, which is the WORST POSSIBLE direction from a perceptual standpoint. So under anechoic conditions there are zero "playback room cues", BUT the presentation of the venue cues on the recording leaves a LOT to be desired because their arrival direction is very UNNATURAL.

 

[Inner Space]

Anechoic stereo listening tend almost be headphone-like with cross-feed with sound "in your head".

I don't find that to be the case. I hear a stereo panorama spread out in front of me, many feet outside my head. Have you actually tried it?

 

[Thomas_A]

Thanks for clarifying.

The in-room reflections are the CARRIERS for the reverberation tails on the recording, and therefore can convey a sense of IMMERSION in the acoustic space of the recording, assuming the venue cues on the recording are the perceptually dominant package of cues.

The anechoic case you mentioned is a completely different animal, wherein ALL of the venue cues arrive ONLY from the direction of the loudspeakers, which is the WORST POSSIBLE direction from a perceptual standpoint. So under anechoic conditions there are zero "playback room cues", BUT the presentation of the venue cues on the recording leaves a LOT to be desired because their arrival direction is very UNNATURAL.

Yes agreed. But the reflections in the lounge room comes from both the direct and reflected sound of the venue. Normally these reflections of the direct sound would be strong, e.g. a singing voice that is 2 meters from the lounge room.

 

[Thomas_A]

I don't find that to be the case. I hear a stereo panorama spread out in front of me, many feet outside my head. Have you actually tried it?

Not in a complete anechoic room, but one very heavily damped room. 30 years ago though, but it was not pleasant.

 

[dlaloum]

Yes, but the OP seems to think it favors box speakers over dipoles and omnis. It doesn't, as far as I can tell.

Dipoles and Omnis require a different setup, you have to consciously use the sound going out the back (and sides) - and you need to have sufficient distance from both rear and side walls, for those reflections not to interfere with the main imaging/soundstaging... so that means the speakers need to be ideally 2m / 6ft out from the rear wall, and a minimum of 1m (preferably 2m ) from side walls.

Use of absorbing/reflecting materials tends to be different, as does the positioning of the speakers themselves.

The test room is set up for mono-directional box speakers - in the testing, only a single solitary example of a dipole electrostatic was used - and was rated very poorly. But there are numerous ELS's and omnis that have been ranked very highly by audiophiles and speaker designers, and this setup does not allow them to achieve their potential.

Having said that, 90% of buyers have no interest in dipoles and omnis, 90% of the market is made up of box speakers - it has its validity, but its validity is limited to the category it was designed for - box speakers.

If I had not been exposed to Quad ESL's in my early 20's - I would have merrily followed the crown, and gone with box speakers....

But once I had heard the Quad ESL63 & ESL57, and the Martin Logan CLS ... there wasn't much out there that came close (circa 1985).

Yes, the average level of quality of box speakers has risen over the years - the mass market speakers are much better than they were back in the day ... but the top end, hasn't moved as much as people think - the best of the 80's and 70's is still very very good indeed.

And yeah those ESL speakers were always demonstrated well out into the listening space - often 3m from the wall behind them and to the side.

 

[dlaloum]

And according to a study done by Wolfgang Klippel (yes, THAT Wolfgang Klippel!) and cited by Floyd Toole starting on Page 185 of the 3rd edition of his book, sound quality and the "sense of space" both contribute equally to the perception of "naturalness", while the "sense of space" slightly dominates the perception of "pleasantness".

By way of example, consider the Polk Audio Stereo Dimensional Array (SDA) speakers, whose extraordinary spatial characteristics only exist in stereo operation. Imo the "rules of the game" should not be applied in a way that works against even ONE outlier speaker which advances some important aspect the art in a worthwhile way. If our priority is exceptional results, we should be inclusive towards exceptional solutions.

I could not agree more !!

The thing that ESL's and Omni's do exceptionally well - and which most box speakers struggle with - is that "sense of space" - much of which is created by the delayed reflections.

That very "sense of space" which completely collapses if a dipole/omni gets placed up against a wall - and which is magnified once they are well into the listening space, and with a reflective wall behind them. Also a bit of side front reflection can be a positive as long as the wall is far enough out to ensure the reflection does not smear the direct sound.

 

[dlaloum]

CEA 2034-A-2015 is about tonality, it misses things like compression. But it's a good start. You can complain about the room all you want, but measurements have shown that the estimated in-room response is pretty darn accurate.

For the type of speakers modeled/tested ... which don't include dipoles or omnis

 

[dlaloum]

And, at that time, many thought so.

And some (I) still do...

 

[Frgirard]

For the type of speakers modeled/tested ... which don't include dipoles or omnis

How many brands sell dipoles or omni?
The models tested are reprensative of what is sold in the market.

 

[dlaloum]

How many brands sell dipoles or omni?
The models tested are reprensative of what is sold in the market.

Then this should be clearly stated .... if you are using an average speaker in an average room - this is a decent approximation.

But if you have sought out something different, perhaps something exceptional - then this probably is not a reasonable reference.

And yes 90% of the market is monopole box speakers.... but when you put together lists of "best ever speaker experiences" - there are lots of planars and omnis that pop up on peoples lists - those speaker types are highly disproportionately represented in the top end... and with good reason.

Many top speaker designers kept a Quad ESL57 as a reference point.... even though they were making box speakers for the mainstream market...

And even among box speakers, many have found alternate means to provide some of the benefits of the planars - usually, a tweeter on the back - Mirage, Definitive Technology, or the legendary Infinity IRS were/are all dipoles/bipoles. (and that is ignoring Quad's, Martin Logans, Magnepans, Acoustats, MBL, Duevel, Ohm Walsh, - all of which are very well regarded / legendary speakers )

This model does not cater for any of these speakers - it is incomplete.

It ignores an entire category (strictly speaking, several categories) of speakers.

 

[Scgorg]

A minor point, but this is implausible. Human hearing in its current iteration has likely evolved over the last half-million years, itself driven by the evolution of articulate and syntactical language since then. People have lived with flat, reflective floors for at best a few hundred years, and many still don't. Not nearly enough time for an evolutionary effect.

Even if we haven't lived with perfectly flat and reflective floors for very long, we've always stood on ground. I think the reflection coefficient of a grassy plain, a rock, sand dunes and more is pretty high in the range of human speech. Doesn't confirm nor disprove Toole's conjecture, but I don't think "implausible" is the term I'd use.

 

[Inner Space]

I think the reflection coefficient of a grassy plain, a rock, sand dunes and more is pretty high in the range of human speech.

You think? We'd need data. A minor point, as I said, but I predict results would show mostly absorption for soft irregular surfaces, and diffusion for hard irregular surfaces - certainly nothing approaching "pretty high" reflectivity in the articulation range. Perhaps that's why we evolved such sensitivity there - why else would we? Ascribing the anomaly to "evolution" strikes me as lazy handwaving.

 

[Scgorg]

You think? We'd need data. A minor point, as I said, but I predict results would show mostly absorption for soft irregular surfaces, and diffusion for hard irregular surfaces - certainly nothing approaching "pretty high" reflectivity in the articulation range. Perhaps that's why we evolved such sensitivity there - why else would we? Ascribing the anomaly to "evolution" strikes me as lazy handwaving.

Yes "I think". I'd love to have data for this, but I am unable to find anything. I am very much struggling to see why hard irregular surfaces would meaningfully diffuse through most of the range of human speech, the variations in geometry simply wouldn't be deep enough. As for absorption - that seems more plausible, especially at the higher ranges of human speech, but as long as we don't have any solid data to go off, this is all just guesswork from both of us.

And again, this is conjecture, Toole admits so himself. He found that listeners aren't very sensitive to aberrations in the floor reflection and formed a simple hypothesis for why that might be. As with many things concerning evolution it's pretty much impossible to make a test which would conclusively give us an answer of whether or not that is the case. Personally I wouldn't consider making a reasonable hypothesis and not testing it (if it even can be tested) handwaving, but that's a matter of personal opinion.

 

[krabapple]

Toole's 'hypothesis' is neither 'his' alone nor presented as a hypothesis , nor does it involve evolving to adapt to built environments. For accuracy's sake it's always good to refer to what he actually wrote

The Fraunhofer Institute in Germany constructed an elaborate listening room in which different room surfaces could be changed (Silzle et al., 2009). “Regarding the floor reflection, the audible influence by removing this with absorbers around the listener is negative— unnatural sounding. No normal room has an absorbent floor. The human brain seems to be used to this.”
Some of this is anecdotal, not the result of thorough scientific investigation. But there is an intriguing logic to the notion that humans evolved while standing on something, and most of what we hear includes reflections from what is under our feet. Wherever we are, reflections from what is under our feet have been useful in gauging distance, among other things. Floor reflections are a part of symphonic performances, jazz club performances, conversations at home or on the street. Is that a problem, a virtue or just a fact of life?

- Toole, Floyd E.. Sound Reproduction (Audio Engineering Society Presents) (p. 193). Taylor and Francis. Kindle Edition.

And btw regarding lateral reflections he refers to 'Barron data' at one point so I don't doubt he's aware of the work. (p 212 of the Kindle versions of the 3rd edition -- it doesn't include a cite for it in the bibliography, so I wonder if that got lost in an edit from the 1st to 3rd editions).

Finally, this thread is seriously mistitled; it has little or nothing to do with the Toole/Harman Spinorama, which is a setup and method for measuring loudspeakers from multiple angles in an anaechoic chamber (analogous to a Klippel), NOT for testing preference for them or for any other acoustic variable. The last Harman listening room employs a "shuffler" device to move speakers rapidly into positions, but this is NOT the 'spinorama'. Listener preference models were developed from experiments in the listening rooms.

 

[Duke]

Then this should be clearly stated .... if you are using an average speaker in an average room - this is a decent approximation.

But if you have sought out something different, perhaps something exceptional - then this probably is not a reasonable reference.

Yes!

I suspect that Harman's research was designed to kill two birds with one stone: To not only advance the industry's knowledge of "what really matters" in loudspeaker design (which was VERY brave of them because, for all they knew, their competitors might take full advantage of their expensive research for free and thereby compete successfully for far less investment), but also to check out how their products fared against specific competitors.

And yes 90% of the market is monopole box speakers.... but when you put together lists of "best ever speaker experiences" - there are lots of planars and omnis that pop up on peoples lists - those speaker types are highly disproportionately represented in the top end... and with good reason...

For twenty-something years I have been a dealer for a speaker which shows up on many people's "best" list, the big SoundLab electrostats. And informed by what the SoundLabs do well, the best of my own designs have been controlled-pattern multidirectional speakers.

And even among box speakers, many have found alternate means to provide some of the benefits of the planars - usually, a tweeter on the back - Mirage, Definitive Technology, or the legendary Infinity IRS were/are all dipoles/bipoles. (and that is ignoring Quad's, Martin Logans, Magnepans, Acoustats, MBL, Duevel, Ohm Walsh, - all of which are very well regarded / legendary speakers )

The first-generation Revel Salon had a rear-firing tweeter!

My understanding is that listening tests during the development of the Salon II found the rear-firing tweeter did not make a difference in preference. IF that conclusion was arrived at by testing in the Shuffler room, the speakers being positioned in front of an absorptive surface (I'm assuming that curtain along the front wall is absorptive at high frequencies, whether or not there is further acoustic treatment behind it) may have rendered the perceived benefit of the rear-firing tweeter negligible.

 

[Kal Rubinson]

The first-generation Revel Salon had a rear-firing tweeter!

As did the first-generation Revel Studio.