I love the way that somehow you have turned things around so that those of us who do perceive phantom images correctly are considered by you to be the ones who have defective hearingThinking again the resent localisation tests with pink noises, and the reason why more than 50 % of the population are not able to hear the loudspeakers as a separete sound sources but they perceive some kind of unreal image in the middle, I have found some light into the matter:
"it has been shown that physiological differences may result in some listeners performing much better than others on auditory localization tasks."
Introduction to Psychoacoustics - Module 08B
Radugazon, this brings some confort to our kind !
It could very well be that those people who cannot locate the speakers as a separate sound sources are just lacking the physiological properties to do so ! Or, it could be that their available processing power is not up to the level of the task !
I would point out that we are perfectly able to locate the individual speakers as separate sound sources on un-correlated signals. Only a correlated signal will generate a phantom image, as it should.
Also you really need to stop throwing around unsubstantiated claims like "more than 50 % of the population are not able to hear the loudspeakers as a separete sound sources" based on an informal and uncontrolled test conducted within this thread.
In all the years I've discussed, read articles about and listened to audio, I've never even once heard of people or seen articles describing people who are unable to perceive phantom images as coming from the centre at high frequencies in the way you describe unless the speakers/room were very poorly set up. (Phasing errors in the speakers, extremely strong ipsilateral reflections etc)
You, on this forum, are the first time I have encountered this claim which leads me to think that either only a very small percentage (low single digits) of the general population has this "problem" or that there is something very wrong with the way you choose to set up your speakers and/or room.
I'd like to see some substantiation from outside references, articles, or research that corroborate your claim that a full 50% of the population are unable to perceive phantom images correctly at high frequencies, otherwise please lay off making this claim as fact continually through the thread...
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There was a resent design in german magazine with 25 pc of 3" elements:
Loudspeaker Kit Twentyfive
- Elias
There was a resent design in german magazine with 25 pc of 3" elements:
Loudspeaker Kit Twentyfive
- Elias
But that's just messing around!
McIntosh XRT2K Speaker, McIntosh XRT2K, McIntosh Loudspeaker XRT2K
Why it should ? Do you have an explanation of why ? Or you just take it as it's given to you ?
P.S. I know at least two other persons out of this forum who don't perceive phantom images. One is a musician (if that matters, who knows).
- Elias
I'm, not sure that I understand the question. Do you mean what is my listening distance? I don't know what you mean by "minimum".
The speakers disappear at all distances except when one gets very close, then the proximity and nearfield effects will make their location apparent, but beyond say 6 feet it's the same everywhere.
I did mean what is the minimum listening distance at which you consider your speakers to sonically disappear. So thanks, that answers my question.
That 25 driver tower looks almost exactly like Roger Russel's version. Apparently a copy, perhaps with different drivers, and the EQ appears to be done passively. Russel's system is apparently up towards $15K a pair (and uses active EQ ahead of the power amp), so it's nice that this copy may make affordable most of the benefit of this design with a total cost of around $2K-ish. I wish I could see the inside of that long closed cabinet. I wonder if Russel does that part differently (?). There would be an end to end resonance to deal with.
If you would study Keele's papers in detail you would see that there are different versions with different "curvature".
Let me turn that around on you, and ask you for an explanation of why we shouldn't perceive a phantom centre image?
Since the vast majority (if not all) people perceive phantom channel images on a properly set up system, the onus of proof is on you to show that this should not be the case.
If you look at the acoustic research you yourself have very recently linked, you should be able to work out how a phantom image forms.
When a mono signal is playing on two properly set up stereo speakers in a properly set up room, both ears will receive the same signal with the exact same amplitude, phase, and time delay.
At mid frequencies up to ~800Hz phase is compared to look for left-right positioning, because both ears are receiving the same signal in the same phase, this localizes the sound along the centre line.
(If only one speaker was playing there would be a phase difference between left and right ear, but with both speakers playing the phase of left and right speakers sum together at each ear to result in the signal at each ear being in phase)
Above 800Hz there is a combination of amplitude comparison and changes in frequency response contour from the pinnae - together the HRTF.
Again amplitude will be identical in both ears at high frequencies, which strongly localizes the sound to the centre line.
The only conflicting cue is that the pinnae response is somewhat different at 30 degrees than at 0 degrees, however research that someone else posted a few pages back (I can't find it now unfortunately) suggested that the amplitude comparison is the dominant factor out to a certain angular azimuth, and that if there is a conflict between pinnae response and amplitude comparison the amplitude comparison wins.
In the case of a single speaker at 30 degrees offset we have both the pinnae response change and a large amplitude shift of high frequencies towards the near ear (largely a loss of high frequencies from the far ear) so the sound is localized at 30 degrees.
In a 60 degree stereo triangle there may still be some pinnae response shift, but there is no amplitude imbalance between ears - both ears are receiving equal amplitude high frequencies with the same frequency response contour, so one major left right localization cue is eliminated, forming an image in the centre.
It's true that the precise frequency response contour will be different than an actual directly ahead single sound source, something that's been discussed in this (?) and other threads in relation to errors in tonal balance of stereo, but without the amplitude imbalance between left and right ear to signal an off centre sound source, how can the brain distinguish this reliably from only the pinnae's modification to the frequency response ? I think the answer is that it can't, at least not at narrow angles.
The pinnae response of the left ear says 30 degrees to the left, the pinnae response of the right ear says 30 degrees to the right, and obviously both cannot be true at once. The amplitude comparison says directly ahead or behind, and because the pinnae response is in the forward hemisphere the brain selects directly forward as the only sensible location for the image.
At much wider angles approaching 90 degrees the pinnae response becomes much more dominant, and it may be the reason why the phantom image starts to pull apart beyond a certain angular separation. (just my hypothesis)
Yes the phantom channel is an auditory illusion which plays tricks on our natural perception of sound localization, so what ? That doesn't make it any less real or valid.
So that's your proof ? Just an anecdote ? No research papers then, on the question of why half the population apparently can't perceive phantom images properly ?
Show me even one piece of research attempting to compare subjects ability to localize phantom centre channel images correctly under controlled conditions which shows that a large percentage of people are unable to do so on the same properly set up stereo speaker system that other people can.
The problem with the informal "test" that was done in this thread should be obvious. Neither listener nor speaker were controlled properly.
We have:
* People who only tested one speaker system with one listener. Of these, some people reported correct perception of phantom images, some did not. As neither listener or speaker was controlled, this tells us nothing about whether the difference was the listener or the speaker set-up. (Everyone was using wildly different speaker designs with different directivity in different rooms)
All we know from this is that two possible perceptions exist, but not whether its a physiological cause or a speaker/room set-up cause.
* Multiple people tested on the same speakers. In this case the results were all uniform for a given speaker/room set-up. In other words there wasn't a different perception for different listeners of the same system. Some systems uniformly provided strong centre images for all tested listeners, while other systems uniformly did not provide strong centre images for all tested listeners.
I shouldn't need to point out how obviously this points the finger at speaker design and speaker/room set-up, not differences in perception between different listeners.
* The final necessary control of the same listeners testing multiple speaker/room set-up's to identify if there were any people unable to perceive phantom images under any circumstances was not carried out.
For this test to be valid they need to be systems not set up or chosen by the test subject, to avoid listener bias in selecting certain types of systems they prefer.
(For example if someone preferred flooders, and therefore only tested different types of flooders, and then doesn't hear strong phantom channel images because flooders may not be able to produce them, this is not a valid test)
I don't disagree that some people may be slightly more critical about the speaker/room setup conditions that are required to give convincing phantom centre channel imaging, due perhaps to differences such as the shape of the head and ears, but I do not believe that there are any significant percentage of people (definitely not 50%) who simply cannot perceive good phantom images regardless of good room/speaker setup that works for other people, nor do I see any evidence for it.
I think that the differences experienced by those in this thread can easily and fairly obviously be explained by differences in speaker design and speaker/room setup.
So I'm calling BS on your continually repeated claim that 50% of the population can't perceive phantom channel images properly on well set up stereo systems.
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There's way too much wiggle in the high frequency response for that to be a reflection free window period, so I'm not sure that that tells us much.Simon, this is for you personally. These are the nearfield EZEQ changes with just the stereo mains on:
Gated above, not gated below.
Simon,
I very much agree to what you've said and also suspect the speaker/room system to cause localization problems because adjusting the toe-in of my speakers results in better or worse center phantom localization.
I know of one person that claims not to hear phantom images at all or at least has problems perceiving a stable phantom image. His solution was to add more speakers (7 front speakers and 8 surrounds).
Lynn Olson also reported that there's one guy he knows with this "condition".
For an unknown reason those people probably can't suppress pinna cues effectively. It's like learning to see side-by-side stereoscopic pictures where one has to release focus and convergence of the eyes (see Stereoscopy - Wikipedia, the free encyclopedia). Some people just can't do it.
I very much agree to what you've said and also suspect the speaker/room system to cause localization problems because adjusting the toe-in of my speakers results in better or worse center phantom localization.
I know of one person that claims not to hear phantom images at all or at least has problems perceiving a stable phantom image. His solution was to add more speakers (7 front speakers and 8 surrounds).
Lynn Olson also reported that there's one guy he knows with this "condition".
For an unknown reason those people probably can't suppress pinna cues effectively. It's like learning to see side-by-side stereoscopic pictures where one has to release focus and convergence of the eyes (see Stereoscopy - Wikipedia, the free encyclopedia). Some people just can't do it.
I wouldn't call it a copy as putting a large series of drivers in a row is not a design so much as a configuration, if I can make a subtle distinction.
If you are of the camp that high directivity and minimization of the room is a good thing then the line array may suit you. It certainly is a good thing that lateral reflections are essentially unchanged relative to a single driver, while floor and ceiling bounces disappear. At the same time the internal length modes would also disappear, since the drive is continuous along the length.
I was the department manager for Mac Loudspeakers from 92 to 95. I am the evil loudspeaker manager that Roger refers to. Nice to be able to write your own history.
David
Simon, this is for you personally. These are the nearfield EZEQ changes with just the stereo mains on:
Gated above, not gated below.
Dan
Strong reflection with 1 meter delay (3.35 ft or 2.9 mSec) based on an average of 340 Hz between peaks.
David S.
Any time I set up speakers in a new room, strength, focus, and stability of the centre phantom image is one of the criteria I'm evaluating when trying different positioning, toe in, room treatment and so on, and it has to be weighed up against other factors like spaciousness, WAF, etc, so there is no doubt that improper room/speaker set-up can damage or even destroy perception of a coherent and stable phantom channel image. I've certainly heard it myself enough times to recognise the fact.
Some speaker designs also tend to produce very strong well focused phantom images even in the face of adverse room conditions, while some other design approaches can fail to produce a coherent well focused phantom channel image even in the best of conditions. Some of the more "exotic" and unusual designs that aim to provide primarily a diffuse field will tend to do this on purpose.
I've heard examples of speakers that have incredible phantom channel imaging almost to the holographic "reach out and touch it" degree, and others that give very little sense of a phantom channel at all - many integrated consumer mid-fi systems I've heard fall into this category - I suspect at least partly due to very mediocre crossover designs in the mid to tweeter crossover region that make no attempt to ensure driver phase tracking or a reasonably flat response through the presence region...
The fact that there is such a variety of speaker designs (especially roll-your-own DIY designs that probably account for most of the speakers owned by this forums members) and variety of rooms and placement options makes it inevitable that some people will be experiencing strong phantom imaging in their current listening set-up and some will not.
I don't discount the possibility that there is a very small percentage of people that either have difficulty perceiving a solid phantom image unless conditions are nearly ideal, or maybe even don't perceive one at all. Some people are colour blind after all, sometimes in subtle ways like red-green.
To claim as fact that it's 50% of the general population without any research or carefully controlled listening tests with a large sample size is preposterous though.
So is advocating the abandonment of stereo as a useful medium on the basis of a few people who don't perceive it the same way as the majority. Should we not bother making colour TV's because a few people are colour bind and can't get the full benefit from them ?
For those people who might have difficulty with phantom channel perception there is always the option to process a 2 channel recording into discrete L+C+R to be reproduced by a 3 speaker system. Most AV receivers can already do this.
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Sound Wave Interference Applet
Given that above 2Khz intensity differences between the ears are the
dominant cue for localization, would please someone explain to me how
stereo is working >2Khz for listeners not listening exactly in the
median plane ?
A few cm difference in listener's distance to left and right speaker makes
a large difference in how the soundfield at the two ears looks like.
It depends largely on the nature of the signals and the kind of stereo
recording technique, whether stereo works at home (at all !).
It is a system, which is very dependent on a multitude of factors not in
the scope of control of the user and thus being error prone.
Please keep in mind, only audiofreaks, professionals and speaker
(developer) nerds (poster explicitly included) are often sitting exactly
in the median plane while listening.
The vast majority of listeners does not. So stereo at least
above 2Khz has nothing but contradicting localization cues for those
listeners.
Broadband signals help, side reflections may help ...
prefereably "later" and "contralateral" but that may to some extent be
the case because common speakers simply have too small DI in upper bass
and midrange: They cannot create early side reflections in highs
without messing up timing information derived from upper bass and midrange
at the same time.
And because radiating highs in a nondiffuse manner, for most speakers early
reflections even in highs will cause coloration due to combing in the very
critical range above 2Khz.
To control directivity in bass and midrange is more costly in development
and production that is why it is not more commonly used, that is how
i explain matters to myself. Sometimes i prefer the more simple explanations.
Given that above 2Khz intensity differences between the ears are the
dominant cue for localization, would please someone explain to me how
stereo is working >2Khz for listeners not listening exactly in the
median plane ?
A few cm difference in listener's distance to left and right speaker makes
a large difference in how the soundfield at the two ears looks like.
It depends largely on the nature of the signals and the kind of stereo
recording technique, whether stereo works at home (at all !).
It is a system, which is very dependent on a multitude of factors not in
the scope of control of the user and thus being error prone.
Please keep in mind, only audiofreaks, professionals and speaker
(developer) nerds (poster explicitly included) are often sitting exactly
in the median plane while listening.
The vast majority of listeners does not. So stereo at least
above 2Khz has nothing but contradicting localization cues for those
listeners.
Broadband signals help, side reflections may help ...
prefereably "later" and "contralateral" but that may to some extent be
the case because common speakers simply have too small DI in upper bass
and midrange: They cannot create early side reflections in highs
without messing up timing information derived from upper bass and midrange
at the same time.
And because radiating highs in a nondiffuse manner, for most speakers early
reflections even in highs will cause coloration due to combing in the very
critical range above 2Khz.
To control directivity in bass and midrange is more costly in development
and production that is why it is not more commonly used, that is how
i explain matters to myself. Sometimes i prefer the more simple explanations.
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I know its been pointed out before, but please don't underestimate the degree of left-right cross talk cancellation above 2Khz afforded by the head and pinnae.
Simple sound wave interference apps like the one you've linked to assume 100% cross-talk between left and right speakers at all frequencies (eg, single omni microphone) which is not how we hear.
We have a head. We have an ear on each side of our head. The ear on one side of our head is occluded from sounds coming from the other side, which leads to a high level of attenuation at high frequencies for sounds from the wrong hemisphere.
Provided that the angular separation of the speakers is great enough, there is enough cross-talk reduction above 2Khz to minimize comb filtering. Because relative phase shift between left and right ear is ignored above 2Khz, only the amplitude variations at each ear caused by comb filtering are important.
If there's very little treble from the left speaker reaching the right ear canal to sum with the signal from the right speaker, there will be very little comb filtering and thus very little amplitude change with lateral head movement.
Without this natural high frequency cross-talk reduction, stereo as we know it would be unusable. What is of interest is whether the same degree of separation is needed for different listeners, I would suggest that it's not, and that it depends on the shape of your ears and head, since its based on occlusion of the pinnae by the head.
(If you had a narrow face and pinnae that stick out sideways a lot, the pinnae can "see" further around into the wrong hemisphere than someone with a broad face and flatter pinnae, and you would probably require wider speaker separation)
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