Does 'envelopment' exist? Can it be measured?

[john61ct]

The left, right, and even surround/atmos channels need to remain full range and than crossed externally into separate bass paths.

Yes, exactly.

Any mono LF content, whether encoded or derived, may simply not need reproducing at all.

or maybe only at say below 50Hz, dominated by / simply reinforcing the higher-frequency content left in stereo form within the L/R channels.

For films, center output set to relatively dominate, perhaps eliminated for music

 

[john61ct]

this whole concept is very difficult to implement in practical situations - which I pointed out several times in the thread, but no one seems to care at all.

I certainly care, that is what makes it a much more attractive goal

 

[Fidji]

As JJ and Lund have repeatedly pointed out, the vast majority of researchers are oblivious to the effect at LF. There has been next to zero research.
One of the few currently accessible due to not being on broken AES site https://audioroundtable.com/misc/icad2005F96.pdf

Good place to start - we are in alignment: nothing exists to clearly manifest AEV, and we can take all opinions on AEV for what they are—opinions.

This leaves us with the next best thing: measurements. Strong proponents of AEV should be able to demonstrate the principle through measurements, yet nothing is available. While it would likely be difficult to measure AEV directly, measurements would at least confirm whether what individuals describe as AEV is, in fact, not just a different set of timbral colorations caused by room resonances.

So it's possible in terms of dimensions of source from listener in a domestic sized room, but not possible with typical domestic type room decay times.
Thus controlling/lowering decays times in the room at LF 40-90hz must be done, unlike the majority of tests that were done and very little/no effect found. Classic GIGO scenario. The impetus for such research, other than Lund, seemingly no longer exists.

You raise the correct question: what is required to demonstrate AEV in domestic conditions?

It is incumbent upon proponents of AEV to produce at least some documentation, e.g. a white paper, "Optimal and Minimal Setup of Audio System for AEV." This should list optimal conditions to demonstrate the effect, including room size, acoustics, speaker placement, EQ, etc.. Additionally, the boundary conditions required to experience AEV must be defined. Again, nothing solid exists, even though it should theoretically be achievable. Providing this data would advance the cause of AEV and potentially justify professional or commercial consideration.

Once we have something tangible on AEV, only then serious discussion about which concept is better - summed or stereo bass and under which conditions, can start.

 

[john61ct]

Stereo bass is obviously just one of the factors.

And there is plenty to discuss about that configuration

Just as with the advantages of multichannel as opposed to stereo-only

Or the idea of big floorstanders vs bookshelf + sub(s), or one sub vs many.

All of these topics are valid points of discussion, completely separate from this thread's topic,

outside of the feelings (emotional dimension) evoked by that physical sensation.

 

[Keith_W]

This leaves us with the next best thing: measurements. Strong proponents of AEV should be able to demonstrate the principle through measurements, yet nothing is available.

You can't demonstrate AEV through measurements. It is a psychoacoustic phenomenon, so the only way to demonstrate it exists is to do experiments with human subjects (and yes, those studies are available). It is the same as being unable to measure soundstage. It's a construct of the brain, and it doesn't exist until the brain reconstructs it from audible cues. You can certainly measure differences in L/R phase, but that does not tell you anything about audibility.

Remember what Dr. Toole said - "an omnidirectional measurement microphone does not hear the same as a person with two ears and a brain". In this context, the actual measurements need to be interpreted in light of psychoacoustic knowledge.

 

[Fidji]

You can't demonstrate AEV through measurements. It is a psychoacoustic phenomenon, so the only way to demonstrate it exists is to do experiments with human subjects (and yes, those studies are available). It is the same as being unable to measure soundstage. It's a construct of the brain, and it doesn't exist until the brain reconstructs it from audible cues. You can certainly measure differences in L/R phase, but that does not tell you anything about audibility.

Remember what Dr. Toole said - "an omnidirectional measurement microphone does not hear the same as a person with two ears and a brain". In this context, the actual measurements need to be interpreted in light of psychoacoustic knowledge.

You can use head and torso with binaural recording to get good approximation of human hearing. And for sure you can demonstrate that what is perceived as AEV vs summed bass is not just adding random resonances and colorations. I am confident there are enough smart people out there, able to design measurements needed to get solid picture.

My understanding is that current trade-off is timbral fidelity of summed bass vs envelopment of stereo bass.

BTW - setup like this could work very well for AEV and one should be able to hear clear benefits if there are any. There is multisub array between the speakers, so it should not be complicated to do comparisons of AEV vs mono-bass and also at which frequency mono-bass stops to be a problem [my guess at around 50-60Hz]

@8x24 inch - what say you> ;-)

https://www.audiosciencereview.com/...h-a-few-words-and-or-links.56410/post-2532832

 

[john61ct]

And again Dr Toole, get a double-blind SPL-matched test set up, with enough biased / fallible humans and enough iterations to get statistical significance

and those subjective opinions turn into scientifically valid results to show which factors are most influential on the preferred / most pleasurable results.

You may not be closer to "defining" the feeling (any more than defining nostalgia or romantic infatuation) but over time the causative elements could maybe be identified.

If only large scale funding were available...

 

[john61ct]

My understanding is that current trade-off is timbral fidelity of summed bass vs envelopment of stereo bass.

Can you link to where that was proposed?

My impression is that the advantage of mono subs (besides lowering costs and space required) is flexibility in placement, making tackling resonance issues like room modes easier.

As with "pinpoint soundstage imaging" being in conflict with expanding the size of the "sweet spot", giving 3-4 people an averaged "not so bad" experience being "muddier" than a precise MLP for a single listener.

 

[dagfinn]

Once we have something tangible on AEV, only then serious discussion about which concept is better - summed or stereo bass and under which conditions, can start.

If you don't accept plain stereo separation as better than mono, there is really no point talking about AEV. If you really can't hear plain stereo, you can just forget AEV. If you accept sacrificing one, the other will go with it. No point of further discussion. Enjoy your mono.

Then those who can hear it and enjoy it, develop and refine it and weed out the destructive parts. Arguing about existance is not productive, particularly when you accept killing stereo, the original recording and premise for AEV.

 

[Fidji]

If you don't accept plain stereo separation as better than mono, there is really no point talking about AEV. If you really can't hear plain stereo, you can just forget AEV. If you accept sacrificing one, the other will go with it. No point of further discussion. Enjoy your mono.

Then those who can hear it and enjoy it, develop and refine it and weed out the destructive parts. Arguing about existance is not productive, particularly when you accept killing stereo, the original recording and premise for AEV.

I have already said it several times, but I will repeat. I am not against anything and I can hear stereo ;-).

After testing several combinations of up to 7 subwoofers to create stereo bass, based on all the research mentioned here [including placing subs at +-110dg] I am of the opinion that in most of domestic environments it is suboptimal solution. I am aware of all of research mentioned here since years and I also love it as a concept. Who does not wish to get "affective touch" from BIllie EIlish? ;-)

I am crossing Waveforming bass to L-R at 60Hz and I can hear all this bass gimmick in Billie Eilish and also in this song, that you posted. So really only things I am missing compared to you are resonances, dips and coloration below 60Hz. I can switch to stereo bass down to 15Hz in 3 seconds if I want, Trinnov allows it. But is not worth it. I get best result with employing customised upmix on stereo recordings - I am adding envelopment via reverb [basically] without creating resonances.

But - as said - hopefully, this times, after all this years that stereo bass idea is out there, something changes and breakthrough comes. But my personal opinion - if it would be so great, somebody would already sell it. There might be several reasons - global conspiracy, vested interests of industry members, technical limitations or simple ignorance. Or maybe, just maybe - it might be not be the best idea after all. But let’s see, looking forward to promised progress from Thomas.

As a side note - as you were posting measurements - try to fix this dip, it is for sure audible and robs you of lot of envelopment. I had something similar in the past and getting it right was great improvement. Can you describe your setup, please - as one of the reasons might be overdamping on mid/upper bass.

 

[Keith_W]

You can use head and torso with binaural recording to get good approximation of human hearing.

Well just because you can measure it doesn't mean you can hear it. Remember what Dr. Toole said, we don't hear the same as microphones, and it's not just the HRTF. Microphones hear SPL measured in dB, we hear loudness measured in Phons and Sones. Microphones hear frequency, we hear pitch. Microphones can plot the frequency response in exquisite and minute detail, but we hear in chunky blocks called ERB's. There is of course a relationship between the two in each case, but the relationship is a nonlinear one and our hearing can be fooled with all sorts of illusions.

And of course, we are much better than microphones at directional hearing. For example, if you hear a sound coming from your left, you can also tell how far away it is. This ability is a combination of several mechanisms, and it's much more than the HRTF, ILD, and ITD. It also involves loss of phase coherence (nearer sounds = more phase coherence) and for us to know the difference between a twig snapping 2m away vs. 30m away, we need to have heard it before and remember what that sounds like. Then there's body positioning, which is tied in with the change in HRTF when the ears change position relative to the sound source.

Unfortunately, our ability to measure with a microphone stops at the eardrum. Further processing in the brain still happens, and that affects our perception, but it can not be measured. We get a whole heap of data in our measurements which somewhat correlate with what we hear. A whole chunk of what we measure can be safely ignored because we won't hear it. But what is relevant, and what is not? The only way to tell is by experimenting on human subjects.

 

[Fidji]

Well just because you can measure it doesn't mean you can hear it. Remember what Dr. Toole said, we don't hear the same as microphones, and it's not just the HRTF. Microphones hear SPL measured in dB, we hear loudness measured in Phons and Sones. Microphones hear frequency, we hear pitch. Microphones can plot the frequency response in exquisite and minute detail, but we hear in chunky blocks called ERB's. There is of course a relationship between the two in each case, but the relationship is a nonlinear one and our hearing can be fooled with all sorts of illusions.

And of course, we are much better than microphones at directional hearing. For example, if you hear a sound coming from your left, you can also tell how far away it is. This ability is a combination of several mechanisms, and it's much more than the HRTF, ILD, and ITD. It also involves loss of phase coherence (nearer sounds = more phase coherence) and for us to know the difference between a twig snapping 2m away vs. 30m away, we need to have heard it before and remember what that sounds like. Then there's body positioning, which is tied in with the change in HRTF when the ears change position relative to the sound source.

Unfortunately, our ability to measure with a microphone stops at the eardrum. Further processing in the brain still happens, and that affects our perception, but it can not be measured. We get a whole heap of data in our measurements which somewhat correlate with what we hear. A whole chunk of what we measure can be safely ignored because we won't hear it. But what is relevant, and what is not? The only way to tell is by experimenting on human subjects.

To sum it up - we cannot measure AEV, there is no controlled testing, only reports of emotional bliss from unreliable sources, works only in undefined special conditions. One could find lot of similarities to magic cables here ;-) .

Back being serious - if we are able to hear it, we are able to measure it, with proper setup, unless whole AEV is just a psychoacoustic illusion. We do understand mechanics of how AEV is created in the brain, so I really do not see a reason not to be able to replicate it in measurements design. And we should be able to correlate measurements to perception. Single sweep with UMIK-1 will not be enough, that is for sure.

I would also argue, that we are better than microphones in directional hearing - something like this is pretty precise https://sorama.eu/products/cam1k/ [we used similar thing in our company for leaks detection], even simple 4-capsule Trinnov mic is much better in localising sound direction than me.

EDIT: to be clear - I am referring to simple “stereo-bass” vs “mono-bass” measurements, that i for sure not that complicated. And we are being told that stereo bass is THE way forward.

 

[goat76]

You can't demonstrate AEV through measurements. It is a psychoacoustic phenomenon, so the only way to demonstrate it exists is to do experiments with human subjects (and yes, those studies are available). It is the same as being unable to measure soundstage. It's a construct of the brain, and it doesn't exist until the brain reconstructs it from audible cues. You can certainly measure differences in L/R phase, but that does not tell you anything about audibility.

I also wanted to bring up the similarities between AEV and soundstage, as neither of them is measurable as they are both psychoacoustic phenomena. As long as we don't have an advanced program that can simulate all aspects of our hearing apparatus, it will be impossible to measure.

@Fidji, have you ever seen anyone being able to measure soundstage, and do you have a suggestion on how such a measurement could be done? If you come up with an easy way to do that, I hope I would be able to provide you with the measurement you are asking for.

 

[olieb]

You can't demonstrate AEV through measurements. It is a psychoacoustic phenomenon, so the only way to demonstrate it exists is to do experiments with human subjects (and yes, those studies are available).

I would agree, that a psychoacoustic phenomenon cannot be measured, unless one has identified the patterns of sound characteristics that might invoke that phenomenon first (if one is able to identify those, which might be hard to do). For that one has to investigate through (controlled) experiments with humans. (In the same way as Toole investigated the "sound preference" that loudspeakers can bring.)

I tried to find papers about such studies but could not find any.
To me the concept of "AEV" as a fundamental (new) "percept" seems rather hypothetical.
Can you point me to these studies, that you obviously know of? As an audio science illiterate I do not have access to AES papers, but the abstracts would already help a lot. (And maybe in a discussion about those papers there are people here with access who can bring in specifics.)

 

[Keith_W]

I would agree, that a psychoacoustic phenomenon cannot be measured, unless one has identified the patterns of sound characteristics that might invoke that phenomenon first (if one is able to identify those, which might be hard to do). For that one has to investigate through (controlled) experiments with humans. (In the same way as Toole investigated the "sound preference" that loudspeakers can bring.)

I tried to find papers about such studies but could not find any.
To me the concept of "AEV" as a fundamental (new) "percept" seems rather hypothetical.
Can you point me to these studies, that you obviously know of? As an audio science illiterate I do not have access to AES papers, but the abstracts would already help a lot. (And maybe in a discussion about those papers there are people here with access who can bring in specifics.)

All these PDF's are free to download:

"Spatial Auditory Display Using Multiple Subwoofers in two Different Listening Environments", Martens et al, McGill University 2005 Link
"Auditory Envelopment: An Undervalued Precept", Thomas Lund Link. Please see his list of references at the end for more studies.
"General Overview of Spatial Impression, Envelopment, Localization, and Externalization", David Griesinger 2000 Link
Floyd Toole's post on ASR Link

There are more papers and I am a bit too lazy to dig them up right now. A good way to find them is to do a member search for "Thomas Lund", scan his posts, and see if he cites any studies.

 

[Oddball]

Well just because you can measure it doesn't mean you can hear it. Remember what Dr. Toole said, we don't hear the same as microphones, and it's not just the HRTF. Microphones hear SPL measured in dB, we hear loudness measured in Phons and Sones. Microphones hear frequency, we hear pitch. Microphones can plot the frequency response in exquisite and minute detail, but we hear in chunky blocks called ERB's. There is of course a relationship between the two in each case, but the relationship is a nonlinear one and our hearing can be fooled with all sorts of illusions.

And of course, we are much better than microphones at directional hearing. For example, if you hear a sound coming from your left, you can also tell how far away it is. This ability is a combination of several mechanisms, and it's much more than the HRTF, ILD, and ITD. It also involves loss of phase coherence (nearer sounds = more phase coherence) and for us to know the difference between a twig snapping 2m away vs. 30m away, we need to have heard it before and remember what that sounds like. Then there's body positioning, which is tied in with the change in HRTF when the ears change position relative to the sound source.

Unfortunately, our ability to measure with a microphone stops at the eardrum. Further processing in the brain still happens, and that affects our perception, but it can not be measured. We get a whole heap of data in our measurements which somewhat correlate with what we hear. A whole chunk of what we measure can be safely ignored because we won't hear it. But what is relevant, and what is not? The only way to tell is by experimenting on human subjects.

I like this. Next time I post my findings, I will cite psychoacoustics. Much easier that bloody REW and arguing about interpreting results.