Internal brain activity defines perception

[Swerd]

A recent scientific study addressed the interesting question that sometimes gets discussed here - What is the role of internal brain activity on perception? I point this out because so much of what we perceive in vision and hearing involves external and internal perception. This paper suggests that the relative part that internal brain activity plays is quite large, and requires prior exposure and learning. There are those in audio who prefer to ignore the internal aspect of perception, and describe hearing as only the external detection of sound waves by the ear and brain. I think they are oversimplifying things. Quite a lot happens between the ears, after the sound arrives at the eardrum. Neuroscience is only beginning to understand this process.

Published in the journal Nature: Fiser, Chiu, and Weliky Nature 2004, vol 431, pp 573-578 and also reviewed by ABC News http://abcnews.go.com/Technology/story?id=186091&page=1. I'll send a pdf copy of the Nature paper to anyone who wishes. Contact me by email or pm.

A few quotes I like:

"When we look at an object, 80% of what we see is internally driven while only 20% has to do with the real thing," said Weliky, the author. "The big question is, what is going on internally to create that picture?"

Weliky says this suggests that as we grow and mature, our brains learn to identify outside images by matching them with our internal understanding of the world. While a young ferret (or child) may notice static or movies, it can't distinguish between them. Adults, meanwhile, have a history of vision to be able to distinguish between the two.

What was surprising is it appears that internal workings of the brain make up 80% of how the adult ferrets interpreted the external world. If extended to people, Weliky says this means our understanding of the world around us must be extremely limited to our own capacity to interpret reality.

 

[Swerd]

Internal vs. external hearing

Usually when I post topics, I toss a rock in the pond, sit back, and let the waves travel on their own. I guess this topic was too abstract, or no one is reading here just after the elections.

This paper shows that as much as 80% of the activity of the brain is concerned with internal interpretation of visual signals. This function is learned through experience. There is no reason for neuroscientists to belive that the visual cortex of the brain differs from the auditory cortex in this aspect.

This paper provides evidence that refutes people who have decided that blind listening tests must be invalid because they don't allow for long-term listening. Usually they claim that their own individual impressions come only after long-term listening to subtle audio differences. If long-term listening is required to detect an audible effect, it is almost certainly because the listener has internally constructed an interpretation of what he is hearing. It is due to what I call internal hearing. It cannot come from the physical behavior of sound waves or the physiological reaction to those sound waves by our ears, what I call external hearing.

We have all heard audio gear that produces noticeably different sounding effects. We usually notice these differences right away or within several minutes. I maintain that these differences are heard by external hearing. I have yet to hear any audio gear that consistently produces in many listeners noticeably different effects that require long-term listenening (internal hearing) to detect the differences. Your internal interpretations may vary from mine, and neither will be wrong. This is how the brain works. No one is fooling himself, unless he concludes that the audio gear and not the brain is directly responsible for this.

 

[mtrycrafts]

Usually when I post topics, I toss a rock in the pond, sit back, and let the waves travel on their own. I guess this topic was too abstract, or no one is reading here just after the elections.

Not abstract, just not much to say afterwards Over 50 people did look at it.

This paper shows that as much as 80% of the activity of the brain is concerned with internal interpretation of visual signals. This function is learned through experience. There is no reason for neuroscientists to belive that the visual cortex of the brain differs from the auditory cortex in this aspect.

This paper provides evidence that refutes people who have decided that blind listening tests must be invalid because they don't allow for long-term listening. Usually they claim that their own individual impressions come only after long-term listening to subtle audio differences. If long-term listening is required to detect an audible effect, it is almost certainly because the listener has internally constructed an interpretation of what he is hearing. It is due to what I call internal hearing. It cannot come from the physical behavior of sound waves or the physiological reaction to those sound waves by our ears, what I call external hearing.

We have all heard audio gear that produces noticeably different sounding effects. We usually notice these differences right away or within several minutes. I maintain that these differences are heard by external hearing. I have yet to hear any audio gear that consistently produces in many listeners noticeably different effects that require long-term listenening (internal hearing) to detect the differences. Your internal interpretations may vary from mine, and neither will be wrong. This is how the brain works. No one is fooling himself, unless he concludes that the audio gear and not the brain is directly responsible for this.

Interesting, of course.

 

[warnerwh]

No doubt brain chemistry has a large influence on how we perceive music. When I'm in a great mood I enjoy music much more than when I'm in a bad mood. Then of course there's numerous other variables affecting the way we feel. The way we feel alters our perception of reality. A person who is depressed will see the world in a different light. You guys will need a trained shrink to go into detail as I don't remember much of college but suffice it to say I suspect everybody who listens to music seriously has noticed their mood affects the way their system can sound.
To make a statement that the system sounds different due to different speaker cabling over a period of time (days,weeks,months) of course cancels out any possibility of being truly objective. Humans are emotional and emotions have a large affect on the way we perceive the world be it color, sound etc.

 

[mtrycrafts]

No doubt brain chemistry has a large influence on how we perceive music. When I'm in a great mood I enjoy music much more than when I'm in a bad mood. Then of course there's numerous other variables affecting the way we feel. The way we feel alters our perception of reality. A person who is depressed will see the world in a different light. You guys will need a trained shrink to go into detail as I don't remember much of college but suffice it to say I suspect everybody who listens to music seriously has noticed their mood affects the way their system can sound.
To make a statement that the system sounds different due to different speaker cabling over a period of time (days,weeks,months) of course cancels out any possibility of being truly objective. Humans are emotional and emotions have a large affect on the way we perceive the world be it color, sound etc.

This should certainly put an end to the long term listeing claims as the mood varies over time and is not very well repeatable

On the other hand, rapid switching would almost guarantee that your mood didn't change in the past few seconds
But real researchers know this and stick to short period, rapid switching protocol.

 

[dlorde]

A post I recently made to another forum might possibly be of interest here (the other forum members just yawned and said "Not interested, let's move on...")

The problem with spending a week or two listening to new kit or layout then swapping back to the old, is that over this kind of period our perception habituates (in the physiological, psychoaccoustic sense), i.e. we become accustomed to the new sound. The effect is much as if you turn the bass boost up high and listen for an hour or two - it no longer sounds so loud, and when you reset it to normal levels, it sounds thin and weedy. Habituation effects occur in pretty much all our senses, in differing ways and over differing timescales. I'm pretty sure this is the expanation behind many of the 'burn-in required' claims. As I understand it, physics/electronics suggests that only mechanical or valve-based components burn-in over periods greater than a few milliseconds, and for mechanicals, the burn-in period should be short and should be achieved during factory testing or very shortly thereafter.

It seems to me that if we don't have some reasonably well-trusted method of comparing different components or layouts over short periods (surely this is what techniques like tune-dem are for?), we find ourselves in a catch-22 situation. If we listen to the new setup for several days, we will become habituated to its sound. If we switch back to the old system, it will sound different until we have habituated to the current one. This means we can't make an unbiased decision based on what we percieve immediately after switching systems if we don't have a means of assessment that is reasonably independent of these effects. Further, if we leave it for another few days, we are in the situation where several days have elapsed since we heard the other system fully habituated. Even if we have rated each system on some scale and kept a written record, there is no guarantee that our physiological and mental state is comparable over each rating period, even assuming the room itself is unchanged (moving furniture, books, or stacks of magazines, etc., can noticeably affect perceived sound). It doesn't take very much to alter our perceptions - a change in mood, exercise, tiredness, full or empty stomach, etc., may all affect how we perceive and how we rate our perception. The majority of these problems will not arise during comparisons over a short time.

Of course, a major difficulty with any comparison over a short timeframe is that, apart from not being able to assess our 'overall enjoyment' of the sound in a thoroughly relaxed state, we generally compare our current system (to which we are habituated) with a new one, so the problem of being habituated to the old system but not the new arises

I believe a technique such tune-dem gives the best chance of achieving useful short timeframe comparisons that are minimally affected by habituation effects, because it is directed less at the emotional response and more at how well we can make out the tune, instruments, etc. I agree that ultimately it is the emotional response that is the objective, but for the reasons above, I don't believe that we can reliably judge between two systems on this basis on either short or long timescales - however I do believe that the system that rates best for tune-dem is more likely to be the system that provides greatest enjoyment long term.

These are arguments based on little more than a smattering of theory, logic and vaguely related experiment (my degree thesis was on physiological response and habituation to environmental noise), and I'm making informed guesses as to the relevant timeframes over which habituation to the sound of a hifi system will occur, so it's all open to question, but it's the best I can do for now

 

[Swerd]

I believe a technique such tune-dem gives the best chance of achieving useful short timeframe comparisons that are minimally affected by habituation effects, because it is directed less at the emotional response and more at how well we can make out the tune, instruments, etc.

I have never heard of the tune-dem technique that you mentioned. Could you fill us in?

 

[Vancouver]

I like to compare your preception of audio and video to drinking wine. If you drink cheap wine for a long time you wont know what you are missing, but as soon as you taste a bottle of '82 bordoue, or St. Francis '97 reseve Zin your palet immidiate develops and the cheap stuff just doesnt cut it any more.

Your brain then learns better taste and since humans by nature are NEVER stasified, so starts the quest to get better and better.

I agree its all preception...the more wine I drink the more refined my perception gets the more I appreciate the suttle differences in good wine. Just like the better sound equipment I listen to the more I realize the suttle differences in audio/video equipment and the more I appreciate it.

You guys dont help either...you are like wine somoliers. (spelling?)

 

[dlorde]

I have never heard of the tune-dem technique that you mentioned. Could you fill us in?

It's very simple - trivially, when comparing two systems, you listen to the music to see how easy it is to follow the tune. How easy is it to 'sing along' to, how easy is it to follow an instrumental line. It's not so much a question of listening for any particular attribute such as 'clarity', 'punch', 'veil', 'air', or 'presence', etc., but for how much of the tune comes across from individual instruments and all together.

I heard about it when I was buying my current system - Linn recommend this technique for comparing components.

See Jim Tate's How To Judge Hi-fi for a better explanation. Linn say "The Tune Dem is how we recommend that our products are demonstrated. When carrying out an A-B demonstration, it is sometimes possible to be confused by extraneous factors such as loudness & tone. The tune dem is a way to compare the two products and decide on how easy it is to follow the tune and appreciate the musical piece as a whole on each one – this allows you to hear quite clearly which product sounds better.
The method involves silent repetition of the sound from the loudspeakers, silently singing along simultaneously with the sound from the speaker. The easier this is to do, the more accurate the system performance."

It works pretty well for me - it's something simple and clear to focus on instead of trying to assess and juggle a whole bunch of vague audio adjectives, or decide which I 'enjoy' more - I don't seem very good at that kind of judgement when trying to choose between systems

 

[dlorde]

I should also say, like many simple ideas, tune-dem gets a lot of over-hyping and a lot of criticism. I see it as just another way to try and discriminate between systems. If you see what it's trying to get at and find it effective, well and good. If not, then use a different way...

 

[Mudcat]

but as soon as you taste a bottle of '82 bordoue, or St. Francis '97 reseve Zin your palet immidiate develops and the cheap stuff just doesnt cut it any more

What's "bordoue"? Does it have a screw on top? Is it a southern Lewsiana version of Bordeaux?

 

[mtrycrafts]

It's very simple - trivially, when comparing two systems, you listen to the music to see how easy it is to follow the tune. How easy is it to 'sing along' to, how easy is it to follow an instrumental line. It's not so much a question of listening for any particular attribute such as 'clarity', 'punch', 'veil', 'air', or 'presence', etc., but for how much of the tune comes across from individual instruments and all together.

I heard about it when I was buying my current system - Linn recommend this technique for comparing components.

See Jim Tate's How To Judge Hi-fi for a better explanation. Linn say "The Tune Dem is how we recommend that our products are demonstrated. When carrying out an A-B demonstration, it is sometimes possible to be confused by extraneous factors such as loudness & tone. The tune dem is a way to compare the two products and decide on how easy it is to follow the tune and appreciate the musical piece as a whole on each one – this allows you to hear quite clearly which product sounds better.
The method involves silent repetition of the sound from the loudspeakers, silently singing along simultaneously with the sound from the speaker. The easier this is to do, the more accurate the system performance."

It works pretty well for me - it's something simple and clear to focus on instead of trying to assess and juggle a whole bunch of vague audio adjectives, or decide which I 'enjoy' more - I don't seem very good at that kind of judgement when trying to choose between systems

Well, at least you know what the other board thinks or doesn't. Their clgged brains are not interested in such discussions

As to your listening technique: You still need bias controlled conditions, no if ands or buts. If you can consistently pick one component over the other to be significant, then this system works too

 

[dlorde]

Well, at least you know what the other board thinks or doesn't. Their clgged brains are not interested in such discussions

Yes, up to a point... oddly enough, it was a Linn-o-phile board - I was just trying to point out some of the things to be aware of when choosing systems and why tune-dem might have an advantage. I know we are illogical, irrational beings at heart, but I feel that unless you can attempt a rational, logical explanation for your approach to choosing hi-fi, you may as well say nothing. They preferred to say nothing...

As to your listening technique: You still need bias controlled conditions, no if ands or buts. If you can consistently pick one component over the other to be significant, then this system works too

Yes, absolutely, and let's be honest - if we can't consistently pick one component over the other by ear, the choice (if made) will depend on other things (price, appearance, reliability, manufacturer, warranty, etc) - there's no shame in that, it's how we should choose any hardware.

 

[mtrycrafts]

if we can't consistently pick one component over the other by ear, the choice (if made) will depend on other things (price, appearance, reliability, manufacturer, warranty, etc) - there's no shame in that, it's how we should choose any hardware.

Exactly. I have nothing against preferences. I have them too

 

[Fate]

An idea

I have an idea. I mean think about it. Fact one: music is all over the brain reacting with everything. Fact two: the brain uses electronic pulses to control itself and the body. Fact three: music is effectively waves or "pulses" running through the air. When this becomes electronic...
It fits all the facts. I mean, why do we dance? We can feel the "motion of the music" (hasn't anyone famous put it something like that before?). I think that the body is hearing these movement orders and choosing to react to them. And if there is some fast music the listeners generally get excited. And some note combonations do not strike these cords in the body and are not pleasing. Is there anything more simple?