The 2011 Richard C. Heyser Memorial Lecture: "Where Did the Negative Frequencies Go?" Nothing is Real

Nothing Is Real
It is a common put-down of audiophiles: "You're imagining things." But is this a meaningful criticism? Is there a real difference between "reality" and "illusion"? Or was Professor Dumbledore on to something?

I have been interested in human perception almost as long as I have been working in magazines. This sound is something with which everyone in this room will be familiar: a 1kHz tone at –20dBFS.

[Play 1kHz, –20dBFS sinewave tone]

What I'd like you to do now is to imagine the same tone for 10 seconds.

I believe a scan of your brain would show the same activity in both situations: with a "real" sound and with an "imaginary" sound. We can't directly experience reality; instead, our brain uses the input of our senses to construct an internal model that reflects that external reality, to a greater or lesser degree. So what is reality, what is the illusion? Internally, they are the same thing. That's why hallucinations are so unsettling—there is no way of knowing without further investigation that they don't correspond to anything in the outside world.

I am sure that some are shifting a little in their chairs, so I will demonstrate this conjecture with some music. A couple of years after the Abbey Road sessions I mentioned earlier, the band got back together to record an album for DJM Records. Here's a picture of us in 1974: three sharp-dressed men.


The Obie Clayton Band (L–R): John Atkinson, Michael Cox, Alan Eden

Baggies and platform shoes were mandatory in 1974, otherwise Mark Knopfler wouldn't have had anything to rail against in Dire Straits' "Sultans of Swing." Here's a needle-drop of a track from our LP, which was released in 1975, engineered by Jerry Boys (of subsequent Buena Vista Social Club fame), produced by Tony Cox at Sawmills Studio, and mastered by George Peckham. (Yes, it was a "Porky Prime Cut.") I am playing bass guitar, I'm one of the backing vocalists, and I supply the choir of clarinets in the bridge.

[Play Obie Clayton Band: "Blues for Beginners," needle drop from Obie Clayton LP, DJM DJLPS 458 (1975)]

Think about what you've just heard. I mentioned bass guitar, vocals, and clarinets. There is also a lead singer, a piano, guitars, drums, a harmonica. What's so unusual about that?

What is unusual is that none of this is real. There are no individual sounds of instruments being reproduced by the loudspeakers. Even though you readily hear them, there is no bass guitar, there are no drums, there is no lead vocalist. The external reality is that there are two channels of complex audio-bandwidth voltage information that cause two pressure waves to emanate from the loudspeakers. Everything you hear is an internal construct based on your culture and experience. The impression you get at 2:51 that someone is striking a match to light a cigarette at the right of the stage is something that exists only in your head, your brain back-interpolating from the twin pressure waves striking your ears that that must have been what happened at the original event.

I first heard this phenomenon described in a talk given by Meridian's Bob Stuart a quarter century ago, and it was discussed at length in Edmund Blair Bolles's A Second Way of Knowing: The Riddle of Human Perception (Prentice Hall Press, 1991). Your brain creates "acoustic models" as a result of the acoustic information reaching your ears. We do this so naturally—after all, it's what we do when our ears pick up real sounds—that it doesn't strike us as incongruous that the illusion of the sounds and spatial aspects of a symphony orchestra can be reproduced by a pair of speakers in a living room.

As with our experience of liquid water, the familiarity and apparent simplicity of perception hides depths of complexity. We just do it. Yet there is as of yet no measurement or set of measurements that can be performed on those twin channels of information to identify the sounds I have just described, and what you perceived with no apparent effort when you listened to that recording of my band.

So if the brain creates internal models to deal with what is happening in the "real" world, let's examine how those models work.


Live from the 131st AES Convention: JA throws a baseball for Stephen Mejias to catch.

I was at a Mets game a few years ago, thinking how difficult it is for an outfielder to catch a pop-up, given that when the ball leaves the bat, the fielder has almost no data with which to calculate where the ball will land. I was reminded of something Barry Blesser wrote in the October 2001 issue of The Journal of the AES (p.886). "The auditory system . . ." Blesser wrote, "attempts to build an internal model of the external world with partial input. The perceptual system is designed to work with grossly insufficient data."

Catching a ball illustrates Blesser's point, not just about the auditory system's but also the visual system's ability to use incomplete information. At first the fielder has very little info on which to create a model of the ball's trajectory. Certainly there is not enough information to program a robot to catch the ball (footnote 1). The robot needs to use math. By contrast, the fielder's brain continually updates the model with new information—a process of successive approximation, if you will—until, plop, the ball lands in his glove.

This internal modeling of reality is quirky. First, with visual stimuli, there is a latency of around 100 milliseconds while the brain processes new data. Visually, we experience the world as it existed a tenth of a second in the past. It has been proposed that we have evolved mechanisms to cope with that neural lag; in effect, our internal models predict what will occur one-tenth of a second in the future, which allows us to react to events in the present—such as catching a fly ball, or maneuvering smoothly through a crowd (footnote 2).

But certain situations can unmask that lag. Something that we must all have experienced is when we have glanced at a clock with a second hand or with a numeric seconds display: The first tick appears to take longer than subsequent ticks. But this isn't an illusion: the first tick does take longer—at least in your reality, as opposed to the clock's—because of the time required for the brain to accommodate new data into its model.

I remember discussing perception with Bob Berkovitz when I visited him at Acoustic Research in Boston, in the early 1980s. The conversation stuck in my mind because Bob, who was working with Ron Genereux on digital signal processing to correct room acoustic problems, defined audio as being "one of the few areas in which an engineer can work without the end product being used to kill people."

During that visit, Bob subjected me to a perceptual test. I sat in a darkened room with a red light flashing in the left of my visual field. At some point, Bob switched off the light on the left and turned on a similarly flashing red light on the right. The question is: What did I see?

The answer is not "A red light flashing on the left, then a red light flashing on the right."

What I saw was a flashing red light on the left that then slowly moved across my field of vision until it was on the right!

It was another moment of satori. The conflict between "reality" and what I perceived seemed to demonstrate that, once the brain has constructed an internal model, it is slow to change that model when new sensory data are received. The brain's latency in processing aural data is shorter than it is with visual data, but it still exists. Otherwise there wouldn't be the phenomenon of "backward masking," where a loud sound literally prevents you from hearing a quiet sound that preceded it.

Here's an audio example analogous to the clock's slower first tick with which everyone will be familiar. When you hook up a new component but with the channels reversed, at first, all you're aware of is that something is not quite right. The orchestral violins are on the left, as they should be, but their image wobbles, and is ambiguously positioned. You don't hear them on the right, where they now should be. Then, when you realize that Left=Right and vice versa, the imaging solidifies and is correctly heard as a channel-reversed image. The thought crystallizes the perception, not the other way around.

Although evolution has optimized the human brain to be an extremely efficient pattern-recognition engine that uses incomplete data to make internal acoustic models of the world, as this example suggests, that same evolutionary development has major implications when it comes to the thorny subject of sound quality.



Footnote 1: Following the lecture, I read in Steven Levy's 1984 book Hackers: Heroes of the Computer Revolution that students at MIT in the 1950s programmed a robot arm to catch a ball, but I don't have any further information on this. Also, on how a fielder manages to catch a ball, I am told that as part of the successive approximation process I describe, he adjusts his position to keep a constant angle between the ball and his eye.

Footnote 2: See, for example, the essay at www.luminous-landscape.com/tutorials/what_we_see.shtml.

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Comments
GeorgeHolland's picture
No you may address me as

No you may address me as George or Mr Holland. Georie is an attempt at making fun but then again that's about all you know to do anyway.

Please ask a relevant question or just shut it.

The lamb would first have to prove they can hear a difference with a dbt

The shepard can buy whatever he wants.

The big bad wolf tried to convince both that the expensive boutique amp was the one to buy

They told him to shove it and bought a less expensive but well built amp and they all lived happily ever after except for Mr Big Bad who soon folded his shop due to no sales.

ChrisS's picture
Mr Big Bad?

So Georgie,

Let's make this question relevant....

Let's say we're testing two amplifiers with two listeners. The first listener is an 18 year old young lady who is trained in classical piano at a Grade 10 music conservatory level. She can hear that Amp A has an excellent range 16hz-40khz through the test system, but even though Amp B doesn't have the same range, she likes the "sound" of it better.  The second listener is the shepherd boy who's grown up now. He's 54 years old, likes big band jazz, but his hearing has been damaged by working with heavy machinery without hearing protection. He can't hear a difference between the two amps.

 

Which amplifier should the ex-shepherd buy?

GeorgeHolland's picture
The 18 year old can hear to

The 18 year old can hear to 40KHz?  Were her parents bats?

"Like" doesn't have anything to do with blind testing. You don't pick which one you "like" you see if you can tell WHICH amp is playing. You don't even know how a dbt test is run I can see already.

 Who cares which amp they buy?  Maybe the people selling them do but that is completly irrevelant to dbt. You have no clue as to what blind testing is all about.

ChrisS's picture
Real World?

Georgie,

Are you a real person or a computer generated figment from JRusskie's russian clone of an old IBM PC? Do you know anyone with normal hearing? Do you know how real people shop or do you isolate yourself in the sanctuary of your closed mind and order everything on-line after reading extensive reviews in Consumer Reports?

ChrisS's picture
Really?

You call those proper Double Blind studies?

GeorgeHolland's picture
Oh so you are an expert on

Oh so you are an expert on double or single blind studies. The ABX system is a proven dbt way to do things. Just because the results have you so upset, you claim the people doing the testing are doing it wrong? Laughable. Tell me some more jokes.

ChrisS's picture
"Hey There, Georgie (Boy)...

...Swinging down the street so fancy-free..."

 

In fact, Georgie, my major(s) for my undergraduate degree were in Developmental Psychology (including Perception) and Statistics (including Research Methodology). So yes, the set up and methodology shown in those links are crap and the results are laughable...

ChrisS's picture
Run Run, Georgie Boy!

Get thee to a local college and enroll in a first year research methodology course. Have fun learning!

GeorgeHolland's picture
Either address me as George

Either address me as George or STFU you stupid little boy. I think you majored in being a twit and smart ass. Who can take anything you say as serious? Grow the fuck up already. You act out like a lil boy with the IQ of a rock.

Go tell the people who make the ABX test system what you just said and see how they laugh you out of the room. You bring nothing to this discussion other than what you don't agree with , with zero facts to back up your claims. Come on show us all how the ABX test methods aren't any good or why the blind testing done in the othe link was faulty. Better yet tell Harman Kardon that their blind testing techniques are faulty and not worth doing.

ChrisS's picture
Go Ask Alice

Georgie,

You must be running out of neurons if you don't trust your own eyes and ears. Yes, the facts are out there.

JohnnyR's picture
Trusting Ears............

.is what SBT and DBT are all about. Using your eyes to test audio products? Well yes I can SEE that YOU would have to look so you would know which one is "better".

ChrisS's picture
Your ears?

Whose ears? Why?

John Atkinson's picture
Not what I have written

GeorgeHolland wrote:
I find it sad that Stereophile keeps saying that DBT or even SBT are not a valid way to test those claims.

Please do not put words in my mouth. That is not what I have said. What I _have_ written is that to design a blind test that limits the variables to just that which you are interrsted in and that produces valid results when there is a small but real audible difference is complicated and time-consuming. The literature is full of poorly designed and performed blind tests that have been proclaimed by audio skeptics as "proving" that there are no audible differences. Such people demonstrate both their ignorance of the Scientfiic Method and their unquesitoning faith in "Scientism."

John Atkinson

Editor, Stereophile

GeorgeHolland's picture
JohnnyR was right more

JohnnyR was right more EXCUSES.

It's pretty simple Mr Atkinson but then having the will or gumption to put a dbt into the line of testing is the first thing you have to have,

You obviously don't have that or just don't care so it's a moot point anyways.

JohnnyR's picture
George, He Never Has Cared.......

.nor ever will when money is involved.

dalethorn's picture
General observation

I would hate to see magazines and websites like Stereophile become intimidated by naysayers who demand "proof" of everything they say, in advance or after the fact. There's a lot of that in mainstream media, due no doubt to controversial topics and false information being fed to reporters. But come on, people - this isn't a mainstream news outfit reporting life or death stories. We have here an incredibly rich article full of facts that can be researched and questioned with references that are well established over time. Instead we have people questioning the author's motives or his pursuit of truth? I think people who are looking for "The truth" should be looking in a religious forum, not a hi-fi forum. There's very little you can "prove" on these topics - the value here is the very informed opinion that costs you nothing.

Ariel Bitran's picture
Hear Ye

nice comment Dale. as an attendee of this lecture, i can tell you it was surely enlightening.

GeorgeHolland's picture
I think you have it all

I think you have it all backwards there friend.....

"I think people who are looking for "The truth" should be looking in a religious forum, not a hi-fi forum. There's very little you can "prove" on these topics - the value here is the very informed opinion that costs you nothing."

Religion is based upon belief and subjectivists cling to their belief, they don't go looking for proof or the scientific method. No you can't prove very much when the reviewers use subjective say so instead of actually measuring the units. Opinons are a dime a dozen or even less than that and worth next to nothing. Just look at all the opinions here.

dalethorn's picture
No George

No, George, you don't get it. You're still stuck in religion, looking for proof of something. Here you get 'information' only, and if you want 'proof' of something, you have to do the work in proving it to yourself. What *you* believe, outside of yourself, is purely opinion. Perhaps all these people looking for truth or proof are just lazy, and trying to intimidate others into doing the work for them. Like bullies.

JohnnyR's picture
Way To Spin........

......the facts there pal. Your "arguement" is FLAT.  The only "info" Stereophile shows us is what the WANT to show us. Cables, power cords, magic bowls are off the list of even testing them in anyway what-so-ever. The reason? Ohhhhh we really don't know how to test those duhhhhh. How lame an EXCUSE is that?  Stereophile is SUPPOSED to be a magazine for information NOT excuses.

"Perhaps all these people looking for truth or proof are just lazy, and trying to intimidate others into doing the work for them. Like bullies."

 BWAHAHAHAHAH!!! that has to be on my "Top 10 WTF Things of 2012"

 You DIDN'T just say that did you???? So let me get this straight, Stereophiles job as you see it is to just fling out "say so" and it's up to the readers to wade through the muck and mire of those reviews to try and grasp one little bit of truth? Yeah right, you must really love it then because they rarely show any truth at all.

Ariel Bitran's picture
Why

why is it so hard to accept that double-blind listening tests are difficult to achieve as JA has explained in his lecture?

the fact that our existences are commandeered by individual perception based on thousands of variables makes it very easy for me to understand, just as how one person may enjoy spicy foods but not grapefruit or where some may hear too much bass and others not enough. so many VARIABLES!!! culture, upbringing, what sounds you are surrounded by, traffic signals, your genetic structure, your actual physical position when listening. perception is a learned skill that we do not choose to accept, it just happens and it is different for every single person.

i think THESE are the sort of differences between individuals that make DBT difficult: everyone hears differently. there is no absolute sound.

the best example of how an ear and sonic preference can change is in the study of language and sounds. the chinese language has a completely different set of sounds to that of the english language, thus their speaking intonation, laughter, and music reflect their cultural and sonic inclinations. eastern and western and andean and greek and celtic and ... and ... all use completely different scales based on their preferences of sound learned over time through language and their environments.

Thus, i often wonder do hi-fi listeners across the globe prefer different sounding systems based on their installed sonic memory? or is there a constant in terms of preference across the globe? probably not. or even more interestingly, can one find similarities in preferences in sound based on linguistic sounds of an individual region? are the frequencies accented in the german language more easily noticed by a german in his hi-fi? DBTs are a waste of time. instead of focusing why not, it is much more fun to focus on the why.

the heart of all of this lies within JA's question: where do the negative frequencies go? there are aspects to our perception of sound that simply cannot be measured because they are based on individual perception which is different for every single one of us.

GeorgeHolland's picture
If blind testing is so

If blind testing is so difficult then how did the people that I linked to manage to do so?  Harman Kardon does blind testing at the drop of a hat. Go ask them how they do it so easily. Mr Atkinson's refusal to do so is simply an excuse as to not have to bring up why cables, power cords and other snake oil is indeed snake oil. He can merrily go along his way as he has for years now ignoring such products and letting his reviewers say whatever BS they want about the sham products and not have to worry one bit. He just doesn't care is the bottom line.

ChrisS's picture
Puddin' and Pie

Georgie Porgie,

That you cite these links as authoritative sources indicates the level of your understanding of testing methodology.

JohnnyR's picture
ChrisSy You Cite..........

......nothing to back up whatever it is you are trying to say but it is amusing.

ChrisS's picture
Some book learnin'

Research methodology courses are taught in colleges and universities all over the world, even Russia...

Let us know when you and Georgie take one.

JohnnyR's picture
Still Nothing ChrisSy??????

Nothing to cite other than your own wandering silly posts? Thought so.

Regadude's picture
At least Chris...

Well little Johnny, at least Chris is A REAL psychologist. He's not a, you know, a hobbyist like yourself...

JohnnyR's picture
I Haven't Seen Any.........

........credentials from ChrisSy just say so. Oh lets see I think I'll be a nuclear scientist now just because I say I am on the forums. There now it's a done deal. Besides how he acts out is more like a 3 year old than an adult. Some professional he is and tell us all again just what your expertise is? Trolling perhaps?

Regadude's picture
I haven't seen any...

...credentials from Johnny the hobbyist speaker designer. Let's see some pictures of your Johnny brand speakers! Post some pics, or provide a link to a site where we can see these speakers of yours.

I demand to see these speakers of yours! 

ChrisS's picture
If A = B and C = B...

If JRusskie has a misguided and limited understanding of DBT, and....

Georgie has a misguided and limited understanding of DBT, then....

Are JRusskie and Georgie one and the same person?

Has anyone seen them in the same room together? Hmmmm.

Please, one of you (I guess it doesn't matter which...) ask Harman Kardon how they do their DBT's and how they use the results.

Thank you.

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