NeuroFeedback and Electroencephalography

Persej

The Living Force
FOTCM Member
Remember that we are listening to MP3 sources, a far cry from audiophile! In particular, the first thing that MP3 encoding does in the interest of compressing is to clobber the high frequency range, only to have the decoder sort of mimicking it back in.
This means that a planar magnetic headphone’s excellent response and fidelity in the highs (up to 50kHz!) is for naught.
The experience might actually be unpleasant – assuming that your auditory system is young enough to perceive the crappy details in the highs: It so happens that we lose sensitivity to high frequencies as we get older.

In a nutshell, listening to NO’s MP3 source with a 300$ planar magnetic is akin to eating a fast food meal out of Joseon chinaware. IMO.
Ok, but what I'm interested is how fast can they deliver sound feedback based on brain waves compared to the ordinary headphones? Besides, we can always use our own music in FLAC if the MP3 becomes the problem.

Besides, all headphones have a fundamental shortcoming which makes many listeners tire rather quickly, become apathic and sometimes slightly nauseated. This because in the production studio, most stereo music is mixed in a way which optimizes the listening experience with external loudspeakers, trying to create a soundstage as wide as possible. To this end, instruments are positioned arbitrarily far apart, without any negative effect because with loudspeakers, both ears are “served” more or less the same sound except that one hears it a bit later, in attenuated and phase-shifted form. In other words, the combination of delay, attenuation and phase shift helps in locating the sound source in our natural way.

In contrast, with a headphone whatever the left channel says goes exclusively to the left ear, same for the right side. So in principle there is no spontaneous cross-feeding between channels to aid in reconstructing a somehow “familiar perception environment”. It seems that this is at the root of headphone listening fatigue.
That would explain why most of those headphones are open. Thanks for explaining that. In that case, HE400S is really the best option.

I don’t have an idea about how much of a factor music fidelity is in shaping NO’s efficacy. I can try and find out, subjectively of course.
It would be nice if you could. But what I'm interested is not music fidelity but speed of feedback that planar headphones give. You might not be able to perceive this consciously, but if there is a difference in speed of feedback, than perhaps the effect of the NO on your brain would be different. I remember that Val said that they worked on improving the audio feedback for the NO3 by making it longer. But perhaps they should've also work on making it faster. And to make it faster, you need faster headphones. Which is what they say that planar headphones are.
 
Ok, but what I'm interested is how fast can they deliver sound feedback based on brain waves compared to the ordinary headphones? Besides, we can always use our own music in FLAC if the MP3 becomes the problem.

That would explain why most of those headphones are open. Thanks for explaining that. In that case, HE400S is really the best option.

It would be nice if you could. But what I'm interested is not music fidelity but speed of feedback that planar headphones give. You might not be able to perceive this consciously, but if there is a difference in speed of feedback, than perhaps the effect of the NO on your brain would be different. I remember that Val said that they worked on improving the audio feedback for the NO3 by making it longer. But perhaps they should've also work on making it faster. And to make it faster, you need faster headphones. Which is what they say that planar headphones are.
Indeed FLAC would be a better choice. Or WAV for that matter. Ever increasing storage capacities at ever lower prices mean less justification for MP3 and the like.

An open headphone does not solve the problem, since the sound from one side cannot travel to the other: open does not imply that sound is radiated to the outside. As far as I can tell, the "open" feature is to avoid resonances inside the cup and the cup material, which might affect the sound especially at high frequencies.

Now to the speed of feedback from brain to NO to ear: it's a matter of a few orders of magnitude difference! Let me explain:
NO's first step is to extract the signal spectrum. Simplifying a bit and assuming all tricks in the book are used, this operation alone takes maybe a second worth of signal samples, and subsequent results will always lag behind the brain by about half that amount of time.

Leaving aside further steps in the algorithm, theoretically at best the audio "interruption" will be issued half a second after the brain "trigger".
A normal over-the-ear headphone reacts to signals within 50 microseconds, then the sound wave travels to the inner ear in say 100 more microseconds. From this you see that within the overall roundtrip, the magnet or membrane reaction speed is a negligible factor.

But even if we were to look at sampling rates (brain signal at 400 microseconds/sample, "interruption" width again 400us), we'd realize that the headphone delay cannot possibly have a meaningful influence.

Here's a neurofeedback session with a 2-5 seconds reaction time, no ten20, no wires, no PC, no MP3, and no cost:-P:-P:-P.
Enjoy!

 
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Divide by Zero

The Living Force
FOTCM Member
On a PC most of the delay is from the software which feeds audio into a sound card driver. There is also a buffer that induces delay because without the buffer- a slight spike in CPU use would make the audio skip.
The NO units use onboard audio ports on the laptops/tablets which has an extra step of slowdown- no dedicated audio hardware, it's done in software.

A cheap in the ear headphone has less delay than the ones that cover the ear, due to distance from the eardrum and a smaller "speaker" inside which has less inertia (and can react faster).

$300-600 for headphones is a bit insane. It's like those vaccuum tube radios and record players that the extreme audiophiles "believe" sounds better. Most of the issues with music is how the music was mixed at the editing studio!
 
A quick update, I've not been able to afford any new NO session since my 5th. I have to be patient. What I notice though is that I feel the need for more. I can see my obsessive tendencies when they point out and I really feel like it helps me deal with that. It's like I began to get away from some thought loops and attitudes but they are remnants. I tend to anticipate a lot still, also I am harsh on myself and still need constant reassurance. I just know more sessions are needed. Fortunately, my family is very comprehensive and communication is always improving between us.
 
Why not just say whatever comes to mind? Sounds very scientific.
Sorry, but you seem to be making fun of the NO project as having no credibility. Just not sure about your's either.
Sorry goyacobol if I came across as making fun. The 100us come from my guesstimate of 3cm distance between driver membrane and eardrum. Depending on a person's anatomy this may be more, or less. That's why the "say 100us" bit. Not whatever came to mind.
BTW as Divide By Zero pointed out, that distance is much shorter in the case of earbuds.

To NO's credibility: I don't understand your point. The topic was whether faster (i.e. higher frequency capable) headphones could improve on the efficacy of NO. I say no, pointing out that in the overall NO signal processing chain a few tens of microseconds are a tiny, negligible quantity. Nothing to do with believability, just facts.
Having said that, after over 30 sessions in the last year I do have many nice things to say about NO, plus a few critical observations. But before posting them here I want to wrap up my homework, IOW make sure I am not going to "say whatever comes to mind". The schnauzer tapping video is part of that homework. All the best,
 

Persej

The Living Force
FOTCM Member
An open headphone does not solve the problem, since the sound from one side cannot travel to the other: open does not imply that sound is radiated to the outside. As far as I can tell, the "open" feature is to avoid resonances inside the cup and the cup material, which might affect the sound especially at high frequencies.
You are right about avoiding resonances, but they do emit sound to the outside.

A cheap in the ear headphone has less delay than the ones that cover the ear, due to distance from the eardrum and a smaller "speaker" inside which has less inertia (and can react faster).
Well, at least that would be easy to test to see if it makes any difference.
 

goyacobol

The Living Force
FOTCM Member
Sorry goyacobol if I came across as making fun. The 100us come from my guesstimate of 3cm distance between driver membrane and eardrum. Depending on a person's anatomy this may be more, or less. That's why the "say 100us" bit. Not whatever came to mind.
BTW as Divide By Zero pointed out, that distance is much shorter in the case of earbuds.

To NO's credibility: I don't understand your point. The topic was whether faster (i.e. higher frequency capable) headphones could improve on the efficacy of NO. I say no, pointing out that in the overall NO signal processing chain a few tens of microseconds are a tiny, negligible quantity. Nothing to do with believability, just facts.
Having said that, after over 30 sessions in the last year I do have many nice things to say about NO, plus a few critical observations. But before posting them here I want to wrap up my homework, IOW make sure I am not going to "say whatever comes to mind". The schnauzer tapping video is part of that homework. All the best,
It's my misinterpretation asino. It did just sound like guesswork and it seems there is no exact idea of the lag time in the software/hardware of the laptops or iPads while using them in the sessions not even counting the earphones response times.

Maybe just like in the dog video (which was actually very cool) the response time does not have to be super fast to get benefits from the feedback. You shouldn't have to walk on eggshells with your posts and I am sorry I jumped to conclusions.

My apologies as well.
 
Maybe just like in the dog video (which was actually very cool) the response time does not have to be super fast to get benefits from the feedback.
Exactly. I find it highly improbable that in our brains and at that subliminal level, microseconds can make a difference. You could say we are slow learners not robots! And besides, time is an illusion...

You shouldn't have to walk on eggshells with your posts and I am sorry I jumped to conclusions.
No problem, but on this forum at least, "eggshells" is my middle name. And this our exchange seems to prove the need to be reasonably precise in order to avoid misinterpretations.
All the best,
rickenbackerpascal :cool:
 

Persej

The Living Force
FOTCM Member
On a PC most of the delay is from the software which feeds audio into a sound card driver. There is also a buffer that induces delay because without the buffer- a slight spike in CPU use would make the audio skip.
The NO units use onboard audio ports on the laptops/tablets which has an extra step of slowdown- no dedicated audio hardware, it's done in software.
Can we use this with NO?

 

Divide by Zero

The Living Force
FOTCM Member
Exactly. I find it highly improbable that in our brains and at that subliminal level, microseconds can make a difference. You could say we are slow learners not robots! And besides, time is an illusion...
I've been watching the series The Brain with David Eagleman and in the first episode you learn how a sound takes around 300ms to process and visual information much longer. There are neurofeedback systems that use visual cues and still they work. So, I think trying to shave microseconds will not really do much if the slower visual path works for neurofeedback too.
 

Persej

The Living Force
FOTCM Member
Well, if our brains process the sound much faster than visual information, than I think that that only says that we should pay attention to audio lag, because many people can feel the difference between monitors in several categories which are sometimes only different in a couple of milliseconds.

For example, they feel the difference in refresh rate - 60Hz (16.67ms per frame) and 120Hz (8.33ms). Some people report feeling the difference with even higher refresh rates, like 144Hz (6.94ms) or even 240Hz (4.16ms).

Then, there is response time - cheaper monitors have 5ms, best ones 1ms (grey to grey).

Then, there is input lag - they range from more than 100ms to less than 10ms.

Of course, it depends on what are you doing. If you are just watching a movie than you don't need more that 24Hz or low response time or input lag. But if you are playing some fast paced game than you could feel the difference. Or so they say so.

And if it does make a difference for people who play video games, which is about visual feedback, than I think it might also make a difference in a neurofeedback with an audio feedback, which is processed even faster.

Maybe you are right that the gains would be negligible, but I think that it's worth experimenting, because gamers showed that sometimes milliseconds can make a big difference.
 
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