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Bass and subwoofers

I have been reading this thread with my limited knowledge of the science behind the acoustics, particularly after my recent comparison of a live afternoon orchestral performance in the wonderful acoustics of the Amsterdam Concertgebouw, and the TV broadcast of the exact same concert the very same evening.
Oh, Amsterdam Concertgebouw!
I too wrote this post #502 on my project thread in January 2022.

This post would be also of your reference and interest, I assume.
- Not only the precision (0.1 msec level) time alignment over all the SP drivers but also SP facing directions and sound-deadening space behind the SPs plus behind our listening position would be critically important for effective (perfect?) disappearance of speakers: #687
 
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Multi channel is not really on for me, with two large Quad 2805 electrostats as my main speakers. I would not want to have five (or more) of those, apart from the fact that there are so few multichannel music recordings.

Glorious venue, excellent loudspeakers - and to consider AE in this context is highly appropriate.

I did not mean to diss (real) stereo. As it stands, there is a better chance of conveying AE to stereo home listeners than to 3D home listeners, in case it was recorded, e.g. at places like Concertgebouw.

I would therefore not invest in 3D home playback until better or more scalable codecs have been developed. Linear audio and Dolby Atmos ADM in 3D production are reliable; but the lossy downstream chain is broken. Consumer Atmos and Apple Spatial are stripped of AE and other audio quality “details”. Then add in-room bass (mis)management to finish it off.

Regarding your stereo system, dipoles generally interact less strongly with the room at low frequency, so it would be interesting to test how reliably the setup conveys AE. You are welcome to DM me for some AE test samples.
 
To make sure I am understanding you correctly - is "Auditory Envelopment" (AE) the same as David Griesinger's stereo bass or what he calls "bassioussness"?

Our studies of AE were inspired by David, Francis Rumsey, JJ and others; as well as by audiology in general.

Unlike Listener Envelopment (LEV) in concert hall acoustics, however, AE is the elementary percept; and differently from the clinical focus, it is unrelated to pathology. Studies even found subjects with material hearing loss readily recognising and enjoying AE. There are more details in the other thread, including pointers to recent papers.
 
Our studies of AE were inspired by David, Francis Rumsey, JJ and others; as well as by audiology in general.

Unlike Listener Envelopment (LEV) in concert hall acoustics, however, AE is the elementary percept; and differently from the clinical focus, it is unrelated to pathology. Studies even found subjects with material hearing loss readily recognising and enjoying AE. There are more details in the other thread, including pointers to recent papers.

Thank you. I am completely ignorant about this field, so I downloaded your paper and i'm reading it. Fascinating. Needs its own thread.
 
@Thomas Lund This is excellent, appreciate the discussion. I have always preferred full range mains (particularly cardioid) to monitor plus sub setups and now I have a better understanding as to why! Even a monitor (or bookshelf) plus sub (monopole, dipole, etc) that supports <50Hz or so I do not experience the same level of “AE” (nice to have a term to ascribe to my experience) as true full range towers (floorstanders). Good stuff, thank you.
 
@Thomas Lund This is excellent, appreciate the discussion. I have always preferred full range mains (particularly cardioid) to monitor plus sub setups and now I have a better understanding as to why! Even a monitor (or bookshelf) plus sub (monopole, dipole, etc) that supports <50Hz or so I do not experience the same level of “AE” (nice to have a term to ascribe to my experience) as true full range towers (floorstanders). Good stuff, thank you.

There's no reason this shouldn't be the same with stereo subs, though. :)
 
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There's no reason this shouldn't be the same with stereo subs, though. :)
Agreed, should have mentioned that … but if you can have all in one cabinet without any other deleterious effects resulting, that is still my preference :)
 
This is all new to me, but from reading this thread and others, I have gotten the idea that for envelopment you want the subs to be located at your sides, or even a bit behind you on the sides, to get the effect best. Meaning subs co-located with the left and right mains in their traditional locations in front of the listener is not as good.
 
Remember my suggestion about nice bass (not sub but bass down to 30's) modules?
That's where is pretty much based on even if this paper was not out back then.

Seasoned audio people talk about it for decades,maybe empirically,maybe after actual study,etc
That's the way to have satellites working in their optimal range while bass do its thing.

It's not for everyone I guess but some may want it (I sure like it,since you hear it you can un-hear it)
 
This is all new to me, but from reading this thread and others, I have gotten the idea that for envelopment you want the subs to be located at your sides, or even a bit behind you on the sides, to get the effect best. Meaning subs co-located with the left and right mains in their traditional locations in front of the listener is not as good.
I don't know if you read all the posts,Thomas describes that as a floorstander quality.
So probably works in front too if not only.
 
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This is all new to me, but from reading this thread and others, I have gotten the idea that for envelopment you want the subs to be located at your sides, or even a bit behind you on the sides, to get the effect best. Meaning subs co-located with the left and right mains in their traditional locations in front of the listener is not as good.
Why not have it all … my system that is being designed now will have full range cardioid mains up front, with monopole subs to the side and behind MLP ;)
 
This is all new to me, but from reading this thread and others, I have gotten the idea that for envelopment you want the subs to be located at your sides, or even a bit behind you on the sides, to get the effect best. Meaning subs co-located with the left and right mains in their traditional locations in front of the listener is not as good.

That probably can't be right, if it works well with floorstanders without subs.
 
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That probably can't be right, if it works well with floorstanders without subs.

Imo "it [creation of the sensation of envelopment] works well with floorstanders without subs" does not preclude "it works a bit better with subs positioned wide to the sides of the listening area".

Not saying such is necessarily always the case, but if the sensation of envelopment at low frequencies is to some extent a function of the phase differential at the two ears, then imo there is an argument to be made for subwoofer positioning which maximizes the perception of that phase differential.
 
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Thank you. I am completely ignorant about this field, so I downloaded your paper and i'm reading it. Fascinating. Needs its own thread.
Thank you for posting this. I had been looking for this occasionally on the Tonmeister Tagung website, but your pointer led me here, which also includes the presentation.

@Thomas Lund
This was extremely interesting! I assume tests A and B could be repeated with lower upper limits (<120 Hz, for example) with similar results, but along the lines of test D, perhaps decreasingly so <80 Hz? Tests C and D were quite interesting--certainly a best case scenario with fully uncorrelated (vs correlated) signal and proximal (~3 ft) sources located 180 degrees with respect to the listener, laterally with respect to the head in C.1 and C.4. I wonder how to extrapolate to varyingly decorrelated signal with more distal LF sources located +/- 30-45 degrees LF source separation from the median plane (as in typical listener setups) and in rooms where modal effects exist--probably cautiously at best, as suggested by figure 5 and the ensuing discussion.

Young-Ho
 
Thank you for posting this. I had been looking for this occasionally on the Tonmeister Tagung website, but your pointer led me here, which also includes the presentation.

@Thomas Lund
This was extremely interesting! I assume tests A and B could be repeated with lower upper limits (<120 Hz, for example) with similar results, but along the lines of test D, perhaps decreasingly so <80 Hz? Tests C and D were quite interesting--certainly a best case scenario with fully uncorrelated (vs correlated) signal and proximal (~3 ft) sources located 180 degrees with respect to the listener, laterally with respect to the head in C.1 and C.4. I wonder how to extrapolate to varyingly decorrelated signal with more distal LF sources located +/- 30-45 degrees LF source separation from the median plane (as in typical listener setups) and in rooms where modal effects exist--probably cautiously at best, as suggested by figure 5 and the ensuing discussion.

Young-Ho
It was tested lower if that's what you mean,except the 72Hz where everyone identified it.
It was tested at below 54Hz where seven of the subjects identified it,below 41Hz where three of the subjects identified it and below 30Hz where no one could identify it.
 
It was tested lower if that's what you mean,except the 72Hz where everyone identified it.
It was tested at below 54Hz where seven of the subjects identified it,below 41Hz where three of the subjects identified it and below 30Hz where no one could identify it.
No, the study population was different in terms of total number (31 vs 10) and likely age range (I'm assuming that the five from tests A and B who went on to participate in tests C and D were not the 6 or 96 year old, for example). The generalizability of tests A and B is much clearer to me than from tests C and D, especially since five of the ten in C and D were described as "experienced listeners."

Young-Ho
 
Imo "it [creation of the sensation of envelopment] works well with floorstanders without subs" does not preclude "it works a bit better with subs positioned wide to the sides of the listening area".

Not saying such is necessarily always the case, but if the sensation of envelopment at low frequencies is to some extent a function of the phase differential at the two ears, then imo there is an argument to be made for subwoofer positioning which maximizes the perception of that phase differential.

I think I’m a bit lucky with the phase differences that occur in my setup where my main floorstanding speakers are not positioned symmetrically in my room, and the subwoofers in a stereo configuration are positioned close by outside each main speaker, which puts them fairly wide in relation to the sweet spot listening position.

The above setup definitely gives me a better sensation of envelopement than I previously had with a single subwoofer, and I guess it has to do with the Auditory Envelopment. I’m not sure the phase differences are maximized, but with some recordings it definitely sound wider and more enveloping than what I have experienced before this stereo setup of subwoofers.
 
Hello @Thomas Lund I have read your study. It appears that if we want "Acoustic Envelopment", we need uncorrelated bass signal, ideally with subwoofers placed on either side of the listener. I have a few questions.

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The first is about the test signal. Pink noise has equal energy per octave, so an uncorrelated test signal would have the same equal energy per octave as the correlated signal. But music is not like this - it does not necessarily have the same equal energy per octave across both channels. So I wonder whether your uncorrelated pink noise was played at the same SPL in both channels, and how much the effect is dependent upon SPL per channel.

Second, the effect of AE was not studied in an enclosed space. To very quickly summarise your findings: with the headphone listening test (Test B), the listeners reported that the correlated signal sounded "small", "constricted", etc. while the uncorrelated signal sounded more "open" and "free". With the subwoofers in the open field (Test C), the same result was reported, but the sensation was more pronounced when the subwoofers were on either side of the listener's ears (Test C1 and C4). And finally, Test D showed that sensitivity to bass direction dropped with longer wavelength with fewer listeners able to identify the difference between correlated and uncorrelated signal.

I wonder whether the effect would still be as pronounced in a listening room, and whether the sensitivity to the effect would start dropping off at shorter wavelengths than those thresholds you found in test D. We already know from other studies (like those of your colleague Makivirta) that sensitivity to group delay is poor for longer wavelengths, and those studies were conducted with headphones and not in a listening room. I imagine it would be even worse in a listening room.

So if it is not uncorrelated SPL that produces the sensation of AE (or more precisely, we don't know since uncorrelated SPL was not tested), it should be uncorrelated timing. But enclosed spaces mess up the timing.

Please don't get me wrong, I really appreciate you doing this research and advancing our knowledge. I am concerned about the generalisability of your findings for typical applications - i.e. people who listen to music in listening rooms.
 
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Hello @Thomas Lund I have read your study. It appears that if we want "Acoustic Envelopment", we need uncorrelated bass signal, ideally with subwoofers placed on either side of the listener. I have a few questions.

View attachment 420710

The first is about the test signal. Pink noise has equal energy per octave, so an uncorrelated test signal would have the same equal energy per octave as the correlated signal. But music is not like this - it does not necessarily have the same equal energy per octave across both channels. So I wonder whether your uncorrelated pink noise was played at the same SPL in both channels, and how much the effect is dependent upon SPL per channel.

Second, the effect of AE was not studied in an enclosed space. To very quickly summarise your findings: with the headphone listening test (Test B), the listeners reported that the correlated signal sounded "small", "constricted", etc. while the uncorrelated signal sounded more "open" and "free". With the subwoofers in the open field (Test C), the same result was reported, but the sensation was more pronounced when the subwoofers were on either side of the listener's ears (Test C1 and C4). And finally, Test D showed that sensitivity to bass direction dropped with longer wavelength with fewer listeners able to identify the difference between correlated and uncorrelated signal.

I wonder whether the effect would still be as pronounced in a listening room, and whether the sensitivity to the effect would start dropping off at shorter wavelengths than those thresholds you found in test D. We already know from other studies (like those of your colleague Makivirta) that sensitivity to group delay is poor for longer wavelengths, and those studies were conducted with headphones and not in a listening room. I imagine it would be even worse in a listening room.

So if it is not uncorrelated SPL that produces the sensation of AE (or more precisely, we don't know since uncorrelated SPL was not tested), it should be uncorrelated timing. But enclosed spaces mess up the timing.

Please don't get me wrong, I really appreciate you doing this research and advancing our knowledge. I am concerned about the generalisability of your findings for typical applications - i.e. people who listen to music in listening rooms.
The enclosed space effect has already been observed, Matthew Poes for example has already replied to this thread.
Problem with in room measurenets is the same with any other measurement and experiment cause rooms are different and what we observe in one of them is different than another.Can't produce valid results this way.
 
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