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Post by Audiophile Neuroscience on Oct 28, 2019 16:24:41 GMT 10
Yes, David agree with almost all you say I only disagree on one thing in your above two posts - If the same difference is consistently perceived between two soundfield then there must be some physically tangible difference between these soundfields which auditory perception can perceive. A measurement of this difference should be possible but may never emerge unless we understand a lot more about auditory perception & there is enough interest/energy/money to develop measurements based on this knowledge. Somehow I doubt this will happen. Hi John yeah you raise a very interesting point. I also believe you're probably right in most cases and certainly this is the traditional way of thinking about the genesis of audible differences i.e. a change in the eliciting stimulus results in a change of the perceived sensation. In a nutshell I suppose this is what psychophysics is about, the relationship between the stimulus and the sensation. I have no problem with this or in measuring the stimulus with the expectation that one will logically follow-on from the other i.e. stimulus and response. However it still is a somewhat reductionist model or put more accurately bottom-up processing, as opposed to top-down processing. Where I am heading with this is that it doesn't take into account that two people can have a different perceptual experience generated from the exact same stimulus. Their top-down processing is different. There may be different central modulation of the signal. It gets a bit crazy because it brings up all sorts of philosophical questions about what is real, or whose version of reality is real. If I take this outside of the audio arena and we look at medicine and specifically pain, this has been widely studied and reported. There is both peripheral and central modulation of pain that occurs differently in people caused by the exact same painful stimulus. Most people with chronic pain syndromes have developed what is called a central sensitisation syndrome meaning that they experience more pain given the same painful stimulus (hyperalgesia) and also can experience the sensation of pain from a non-painful stimulus (allodynia). It is known that multiple other factors influence the experience of pain from emotions to attentional factors and so on. These can not only modulate the neurological signal and amplify pain but a vicious circle and feedback loop from top-down processing actually starts changing the physical structure of the nervous system, a bit like a muscle grows bigger when you exercise it, the nervous system responds in this case in a maladaptive fashion to more or less permanently enhance the experience of pain. A cruel trick. So I suspect similar phenomena potentially adaptive or maladaptive can occur in auditory processing and change the way one individual processes a sound field compared to another. If so, there needs to be no variation in the stimulus between the two observers.
All that said I see no particular reason to proffer a permanent change in the central neurological processing of sound in order to explain perceptual differences of individuals. We all perceive things differently for a variety of reasons and I submit without any necessarily tangible difference between the physical stimulus. I agree that if the change in perception has occurred within the one individual when listening to different sound fields then you would expect that the sound field has changed. I don't think it necessarily has to be that way as it would logically follow from the above model that even within the same individual something else may have changed in the central processing of the neurological signal within that same individual. This for example could explain why an individual can quite easily hear significant differences but when placed in a blind test pressure situation the central processing of the signal collapses and poof, the perception collapses. Personally I am just as happy with this explanation causing false negatives in blind testing as I am the possibility of expectation bias causing false positives.
David ----------------------------------------------------------------------------------------------------------------------------- "All music is folk music. I ain't never heard no horse sing a song." - - Louis Armstrong
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jkenny
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Post by jkenny on Oct 28, 2019 22:39:38 GMT 10
Right, I see your point, David - I guess I was talking about agreement among many people in agreement about how they perceive a particular soundfield. My belief being that this is a bottom-up process caused by the signals in the soundfield but a measurement has not yet been discovered/developed.
What you are talking about is an individual's top-down processing which I completely agree with & I've made this point in the past - what's the true reality if when someone does a blind test of some device & finds no audible difference & yet when they then go back to their normal listening they consistently find an audible difference with this device? Nobody ever replied to this but the true reality for that individual is the latter.
It's similar to what SAM was stating about illusions - it doesn't matter how much we "know" that it's an illusion if our perception always sees the illusion & not "the reality" - the straight lines will always appear bent, the lips will always appear to say "Fah" rather than "bah"
One has to accept that our perceptions work in the way they work. There's no point in trying to make unnatural situations to test our perceptions when they have developed to act as a useful interface to the world, not necessarily a 100% accurate interface & some, Donald Hoffman for instance, would say that our senses/perceptions present us with a very nuanced/inaccurate version of "what's out there" but a version that serves its main purposes of survival & procreation. He likens perception to a computer interface i.e an abstraction of what's going on in the background - so dragging a file to an icon of a waste basket hides a lot of the underlying reality but allows us to interact with this reality.
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Post by Audiophile Neuroscience on Oct 29, 2019 11:24:01 GMT 10
Right, I see your point, David - I guess I was talking about agreement among many people in agreement about how they perceive a particular soundfield. My belief being that this is a bottom-up process caused by the signals in the soundfield but a measurement has not yet been discovered/developed. What you are talking about is an individual's top-down processing which I completely agree with & I've made this point in the past - what's the true reality if when someone does a blind test of some device & finds no audible difference & yet when they then go back to their normal listening they consistently find an audible difference with this device? Nobody ever replied to this but the true reality for that individual is the latter. It's similar to what SAM was stating about illusions - it doesn't matter how much we "know" that it's an illusion if our perception always sees the illusion & not "the reality" - the straight lines will always appear bent, the lips will always appear to say "Fah" rather than "bah" One has to accept that our perceptions work in the way they work. There's no point in trying to make unnatural situations to test our perceptions when they have developed to act as a useful interface to the world, not necessarily a 100% accurate interface & some, Donald Hoffman for instance, would say that our senses/perceptions present us with a very nuanced/inaccurate version of "what's out there" but a version that serves its main purposes of survival & procreation. He likens perception to a computer interface i.e an abstraction of what's going on in the background - so dragging a file to an icon of a waste basket hides a lot of the underlying reality but allows us to interact with this reality. Hi John totally agree that the bottom-up processing scenario where there is a change in the audio signal being perceived but not as yet measured can result from failure of the test and/or its application. It will depend on the sensitivity and specificity of the test et cetera.
If someone does a blind test and finds no audible difference but the difference is audible under normal listening circumstances then the "true reality" depends on how you look at it. From a scientific point of view there are all the usual possibilities as discussed in audio fora. I believe them to be valid possibilities. Philosophically I agree with you that the "reality" for the person, if you like, has shifted. But my point would be that both versions of reality, both experiences at the time, are equally "true" for that individual. It really then comes down to what school of philosophy you prefer as to determining what is real and what is not real. With tongue-in-cheek just a little, how do you know what is real? The only way you can determine that something an illusion – even a commonly shared illusion – is by comparing it to another perception i.e. another observation. Who's to say which perception is real? Illusions can be shared by many people and then other people come along and demonstrate by their different shared observations a different so-called reality.
Esse est percipi in a nutshell perception is reality (to be means to be perceived), reality is a perception, perception is subjective, reality is subjective. The reality of the outside world is contingent on the knower. I guess similar to agnostic existentialism, the concept of existence is subjective. And then you have Plato's allegory of the cave and so forth, memes like "reality is an illusion albeit a persistent one" said to be attributed to Einstein but perhaps apocryphal.
So it's kind of a moot point in many ways to talk about " illusion if our perception always sees the illusion & not "the reality". One man's illusion is another man's reality and vice versa. I think though on a much more practical level there is a reality that we all agree upon or at least we all accept as reality. We simply benchmark this version so that by default we can call anything else either an illusion, delusion or hallucination. Having worked briefly in neuropsychiatry its fun to have discussions about what is "normal". At the end of the day the psychiatrists look up a book called DSM 5.
David ----------------------------------------------------------------------------------------------------------------------------- "All music is folk music. I ain't never heard no horse sing a song." - - Louis Armstrong
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jkenny
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Post by jkenny on Oct 30, 2019 10:37:40 GMT 10
Yea, the whole delusion, illusion, reality thing is in some ways a philosophical argument but is also a practical one. Our agreed upon reality is simply an acceptance of how our perceptions work, flaws & all. For instance our eyes are a basic wrong design - the nerve fibres run in front of the rods & cones except in the region of the small area called the Fovea. Hence we have a central focus point & peripheral vision which is out of focus. Obviously, this is wrong design & is not so in some other creatures where nerve fibres are behind rods & cones. So starting with this design flaw, I'm not sure people actually understand what is meant by our brains processing of signals creates what we perceive. This can seems like a simple statement but is actually profound (applies to auditory perception also). There is no image as such - my simplistic understanding/description of visual perception will no doubt be corrected by more knowledgeable here but what I understand of it is that the brain receives parallel streams of nerve impulses which represent various aspects/characteristics (colour, motion & form) of the original image & which need to be bound together to create the visual objects in the vista. A good introduction here theconversation.com/how-do-our-brains-reconstruct-the-visual-world-49276And here's an interesting experiment www.newscientist.com/article/2131864-our-brains-prefer-invented-visual-information-to-the-real-thing/Another interesting experiment here discovermagazine.com/1993/jun/thevisionthingma227 which gives more detail about the working of visual perception
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sandyk (RIP Alex, 1939 - 2021)
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Synchrodyne PLL AM tuner (Phase Lock Loop),Stereo Tape Deck, Amplifiers including I.C. types, Class A, Class AB 100W/Ch. (ETI5000) 240W/Ch. Mosfet (AEM6000) ,several DACs , numerous PSUs including VERY low noise (<4uV) types etc.for myself and friends
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Post by sandyk (RIP Alex, 1939 - 2021) on Oct 30, 2019 12:10:30 GMT 10
Yea, the whole delusion, illusion, reality thing is in some ways a philosophical argument but is also a practical one. Our agreed upon reality is simply an acceptance of how our perceptions work, flaws & all. For instance our eyes are a basic wrong design - the nerve fibres run in front of the rods & cones except in the region of the small area called the Fovea. Hence we have a central focus point & peripheral vision which is out of focus. Obviously, this is wrong deign & is not so in some other creatures where nerve fibres are behind rods & cones. So starting with this design flaw, I'm not sure people actually understand what is meant by our brains processing of signals creates what we perceive. This can seems like a simple statement but is actually profound (applies to auditory perception also). There is no image as such - my simplistic understanding/description of visual perception will no doubt be corrected by more knowledgeable here but what I understand of it is that the brain receives parallel streams of nerve impulses which represent various aspects/characteristics (colour, motion & form) of the original image & which need to be bound together to create the visual objects in the vista. A good introduction here theconversation.com/how-do-our-brains-reconstruct-the-visual-world-49276And here's an interesting experiment www.newscientist.com/article/2131864-our-brains-prefer-invented-visual-information-to-the-real-thing/Another interesting experiment here discovermagazine.com/1993/jun/thevisionthingma227 which gives more detail about the working of visual perception Hi John You aren't by any chance also a B.Sc ? Kind regards Alex
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jkenny
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About Me: Audio equipment designer forever in pursuit of more realistic & engaging music reproduction purely because of the extra enjoyment of music created by such reproduction.
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Post by jkenny on Oct 30, 2019 19:31:45 GMT 10
Yea, the whole delusion, illusion, reality thing is in some ways a philosophical argument but is also a practical one. Our agreed upon reality is simply an acceptance of how our perceptions work, flaws & all. For instance our eyes are a basic wrong design - the nerve fibres run in front of the rods & cones except in the region of the small area called the Fovea. Hence we have a central focus point & peripheral vision which is out of focus. Obviously, this is wrong deign & is not so in some other creatures where nerve fibres are behind rods & cones. So starting with this design flaw, I'm not sure people actually understand what is meant by our brains processing of signals creates what we perceive. This can seems like a simple statement but is actually profound (applies to auditory perception also). There is no image as such - my simplistic understanding/description of visual perception will no doubt be corrected by more knowledgeable here but what I understand of it is that the brain receives parallel streams of nerve impulses which represent various aspects/characteristics (colour, motion & form) of the original image & which need to be bound together to create the visual objects in the vista. A good introduction here theconversation.com/how-do-our-brains-reconstruct-the-visual-world-49276And here's an interesting experiment www.newscientist.com/article/2131864-our-brains-prefer-invented-visual-information-to-the-real-thing/Another interesting experiment here discovermagazine.com/1993/jun/thevisionthingma227 which gives more detail about the working of visual perception Hi John You aren't by any chance also a B.Sc ? Kind regards Alex
You found me out, Alex
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sandyk (RIP Alex, 1939 - 2021)
Global Moderator
Posts: 226
About Me: Retired ex Principal Telecommunications Technical Officer with 43 years at Telstra (Australia)
I am also a Moderator in Hi Fi Critic Forum
Electronics hobbyist for >65 years with DIY projects including Loudspeakers, Stereo FM tuner, S/W Regen Receiver, Superhet AM ,
Synchrodyne PLL AM tuner (Phase Lock Loop),Stereo Tape Deck, Amplifiers including I.C. types, Class A, Class AB 100W/Ch. (ETI5000) 240W/Ch. Mosfet (AEM6000) ,several DACs , numerous PSUs including VERY low noise (<4uV) types etc.for myself and friends
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Post by sandyk (RIP Alex, 1939 - 2021) on Oct 30, 2019 20:05:02 GMT 10
Hi John Alzheimers hasn't quite set in yet .
Regards Alex
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sandyk (RIP Alex, 1939 - 2021)
Global Moderator
Posts: 226
About Me: Retired ex Principal Telecommunications Technical Officer with 43 years at Telstra (Australia)
I am also a Moderator in Hi Fi Critic Forum
Electronics hobbyist for >65 years with DIY projects including Loudspeakers, Stereo FM tuner, S/W Regen Receiver, Superhet AM ,
Synchrodyne PLL AM tuner (Phase Lock Loop),Stereo Tape Deck, Amplifiers including I.C. types, Class A, Class AB 100W/Ch. (ETI5000) 240W/Ch. Mosfet (AEM6000) ,several DACs , numerous PSUs including VERY low noise (<4uV) types etc.for myself and friends
Audio Industry Affiliation: NIL
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Post by sandyk (RIP Alex, 1939 - 2021) on Jan 9, 2020 18:24:56 GMT 10
An interesting visual illusion.
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jkenny
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About Me: Audio equipment designer forever in pursuit of more realistic & engaging music reproduction purely because of the extra enjoyment of music created by such reproduction.
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Post by jkenny on Feb 7, 2020 3:12:26 GMT 10
We probably have all seen this before but it's central messages are the same as Donald Hoffman: - our perceptions have not evolved to present accuracy of the outside world to us internally but rather to present what's useful to us in interacting with the world - illusions show us the workings of perceptions which revolves around our learning of the behaviour of objects in the world & is, as a result, all context based
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