EEG shows brain can simultaneous encode two speech streams
130 points
5 hours ago
| 25 comments
| journals.plos.org
| HN
NalNezumi
35 minutes ago
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Related, but this reminds me of the story by Richard Feynman [1] when he practices counting up to 60 seconds in his head, and after many experiments around what he can do simultaneously conclude that he can simultaneously count and read but not speak. Later sharing this to John Tukey, he's told that Tukey can't read while counting but could speak while counting.

Turns out Tukey is visualizing looking at a tape, while he counts, while Feynman imagined himself talking to himself, so he couldn't speak while counting but Tukey couldn't read while counting

>By that experience Tukey and I discovered that what goes on in different people's heads. when they think they're doing the same thing - something as simple as counting - is different for different people. And we discovered that you can externally and objectively test how the brain works: you don't have to ask a person how he counts and rely on his ownobservations of him-self; instead, you observe what he can and can't do while he counts. The test is absolute. There's no way to beat it; no way to fake it.

>It's natural to explain an idea in terms of what you already have in your head. Concepts are piled on top of each other; this idea is taught in terms of that idea, and that idea is taught in terms of another idea, which comes from count- ing, which can be so different for different people!

>I often think about that, especially when I'm teaching some esoteric technique such as integrat- ing Bessel functions. When I see equations, I see the letters in colors-I don't know why. As I'm talking, I see vague pictures of Bessel func- tions from Jahnke and Emde's book, with light- tan j's, slightly violet-bluish n's, and dark brown x's flying around. And I wonder what the hell it must look like to the students.

[1] https://calteches.library.caltech.edu/3591/1/Feynman.pdf

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a_gopher
1 hour ago
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If reading aloud a children story, you may notice you are able to maintain an independent unrelated train of thought. While doing so, I notice that occasionally extra mistakes can "leak" into the story telling - e.g. you read a single word incorrectly, maybe substituting a word from your other train of thought.
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thedanbob
32 minutes ago
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When I was a kid, my dad (a physicist) would often read stories to me and my brother. He would sometimes fall asleep while reading, and we could tell when that was coming because suddenly our children's story would stop making sense and get filled with all these big physics terms.
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johnisgood
7 minutes ago
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Oh yeah, I have been sleep deprived so much that the things that I said made no sense. I still formulated sentences but they did not have any meaning. In fact, I noticed this myself and I was like "fuck, what I just said made no sense". This happened a few times. It is a pretty interesting experience.
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lqet
27 minutes ago
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The ability of the brain to do that gives me 15 min of quiet time to think about problems each evening. But you cannot follow the story in that mode, and the whole facade will collapse on a single innocent question...

> "Dad, why did he steal the biycle?!?!"

> ".... what?"

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Dibby053
16 minutes ago
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In school, our teachers made us take turns reading the textbook. When it was my turn, I focused entirely on how my voice sounded, trying to match my cadence and tone to the punctuation. The moment I finished the paragraph, I would have to quickly re-read it in silence just to understand what it actually said.

I think I still can't read a non-trivial text aloud while trying to make sense of it at the same time. I need the two streams just for one text.

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Neil44
46 minutes ago
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Yeah it's like I suddenly realise I haven't been thinking about the reading and I'm near the bottom of the next page somehow.
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Muhammad523
1 hour ago
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I can do that, and i notice that i kinda stop thinking about the reading and put more "brain resources" into the independent train of thought. Then i realize i was reading all the time without putting any effort in it
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barrenko
1 hour ago
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Interlinked.
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_ink_
1 hour ago
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I definitely cannot do that. Crazy.
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bell-cot
1 hour ago
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The ability may take time to develop. If you have a couple under-5 children handy, who'd love the ritual of having the same ultra-simplistic and repetitive books read to them every night, night after night after night, when your head is probably full of grownup stuff that you gotta get done...
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Marciplan
1 hour ago
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or any other reading for that matter!
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adverbly
7 minutes ago
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I wonder if parallel processing is related to musical training or ability.

I've always been jealous of people who can play the drums and sing or play piano with both hands and a foot while singing.

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DrScientist
2 hours ago
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If you couldn't process multiple streams ( audio/visual/other senses ) how would you ever be able to monitor the background for danger and context switch?

There is a difference between conscious experience and what's going on in the background.

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avianlyric
1 hour ago
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There’s a big difference between processing multiple streams, and processing multiple streams simultaneously.

You can achieve the former, without the latter, by doing time slicing. Spending a small amount of time processing stream A, then dropping that and processing stream B for a moment, then swapping back. Just like how a single core CPU can process multiple threads.

Proving the brain is continuously processing and encoding multiple streams simultaneously is an interesting finding that helps us better understand how our brains handle multitasking. That’s absolutely something worth studying and understanding, even if the headline discovery “feels” obvious. It the precise mechanism that’s interesting, not the effect the mechanism produces.

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gala8y
1 hour ago
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When I meditated a lot, I was able to sit in a cafe and listen to 3 conversations without switching and be able to understand them and remember them all. It happened to me few times. Also, once, sleeping in a tent, a voice from a dream interfered with sound of raindrops and became distorted and I woke up scared only to quickly get what just happened.
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aatd86
31 minutes ago
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Not sure why you are downvoted. Well it probably doesnt require meditation because split attention is somewhat common here. My mother can follow multiple discussions like have a phone conversation and understand what I tell her. In general I can't.

So a bit harder for me. I can focus on work and follow some podcasts but not speak and at the same time listen to a full parallel convo.

I do believe brain to brain communication exists from experience too. People will be quick to call it schizophrenia and indeed it can be maddening because it evidently reuses your neurotransmitters for information propagation. That includes dopamine and can lead to the same issues some diagnosed people have, but actually a couple at the same time.

Without visual hallucinations but the brain gets a bit taken still, since it has to share processing. So it can induce adhd like symptoms, loss of phantasia, nucleus acumbens becoming nucleus incumbered :D, impaired motivation, etc.. But it is transient and you can argue it within yourself with some amount of relief. If you notice and start a loop of wondering where it comes from you are toast though.

Anyway, probably saying too much. You have to experience it. Probably someone playing with AI and neurochemistry. Still can't figure out the actual transport system. It does not make much sense from a wavelength point of view. Even if merely HF acoustic waves (since they can be more directed) not quite sure. Should ask whoever big galaxy brain created the havana effect... \sarcasm

At the same time people already know publicly how to decode brain signals and turn them into movements and Computer Interface actions. So the brain is not a complete blackbox. Some people might be further along...

Anyway... we will know eventually what is this all about..

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coldtea
2 hours ago
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This is about multiple speech streams.

More specific from the mere ability to process multiple sensory streams in general.

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21asdffdsa12
1 hour ago
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There is also a different quality of processing. Textunderstanding and danger deciphering of signals.
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subhro
4 hours ago
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As a pilot and a radio officer, I have always been able to process and service 2 audio streams simultaneously. So not surprised with this finding.
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TobTobXX
3 hours ago
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That tracks. As a teacher I sometimes find myself conversing with multiple kids simultaniously as well. If it's nothing too deep that requires full focus, it works. (Though I do find it tiring and avoid it.)
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junon
4 hours ago
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Perhaps a dumb question but are they center panned (or mono, i.e. talking over each other) or is it split left ear/right ear when they come through the headset?
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sigmoid10
3 hours ago
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Airplane radios are generally broadcasting and receiving mono. There are modern headsets that can also play stereo, but only for onboard music or intercom purposes, if the plane supports it. But in planes with 2 radios you can usually configure their I/O individually. So you can listen (and also talk, although that makes sense less often) on two frequencies at the same time.
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junon
3 hours ago
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Yes of course, the transmitted audio would be mono. I meant one radio in one ear and another radio in the other ear, or if you mix them and they both play in both ears. But it sounds like they're mixed (talking over each other in a single audio stream).
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subhro
3 hours ago
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They are mono, but I was trying to say that with practice, you can process 2 independent audio streams simultaneously irrespective of whether they are mono or stereo. For example, I am able to keep track of 2 people talking at the same time. I obviously can't respond to both but can maintain independent contexts.
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CompoundEyes
2 hours ago
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I think it was wondered whether you were having the independent streams panned hard to the left and right ears and if that had something to do with hemispheres of the brain and the processing efficiency.
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ndr
3 hours ago
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I wonder if piano players find that easier too, compared to lay people.
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stavros
1 hour ago
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I do it too, but I "buffer" one person's speech while I process the other's, and vice versa. Do you process both at once?
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HPsquared
58 minutes ago
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I wonder if reading techniques (i.e. human TTS) are also a bit like this. You have to "read ahead" and maintain a mental buffer, in order to parse the sentences so that you can put emphasis in the correct places, timing etc. So the eyes and mind are ahead of the speech.
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ChrisRR
1 hour ago
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I had assumed this was already well known.

My issue is that I can't stop processing other speech streams. It seems other people can tune out conversations around them when talking to a person but I have to hear every word

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dr_dshiv
3 hours ago
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“Bilocation” was one of the legendary superpowers of Pythagoras (he was miraculously able to lecture in two cities at the same time).

Whenever I’m in multiple conversations at once in a social setting, I think of Pythagoras

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lokimedes
3 hours ago
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Many mindfulness practices seem to direct attention at two place at once, to quiet the inner voice. Perhaps this relates to more than just speech, but to attention itself. George Gurdjieff's "The Fourth Way" deals with self remembering, and his pupil, P. D. Ouspensky, has a very vivid description in [1] of how focusing on two things at once leads to a changed state of consciousness, that seems like meditation, and comes from the saturation of the two streams of attention.

[1] https://en.wikipedia.org/wiki/In_Search_of_the_Miraculous

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Gehinnn
2 hours ago
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I believe this is why fugues are such a pleasure to listen to!
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mulhoon
42 minutes ago
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Anecdotally, I have 3 young kids who sometimes all talk to me at once. It's impossible to process, but with 2, I've noticed it IS kinda possible process.
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saidnooneever
42 minutes ago
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ask any dj who doesnt use modern sync tools and they will tell u, u can follow 2 entire songs out of sync of eachother fine, it takes practice but your brain can get used to these kinda tasks. (ofc very unscientific here :D)
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shtack
32 minutes ago
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I’ve actually found that I’m able to process two speech streams and one music stream independently from those. At least for me, music seems to have a dedicated sub-processor of sorts.
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t23414321
3 hours ago
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Then it is known that if you play to someone with small delay what he says he will be lost on both - so he can't think about and listen to what he is saying if it's not one stream.
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cheschire
1 hour ago
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Supported by the empirical evidence of cube farms, post COVID in the early “return to office” days, when office etiquette was completely forgotten and people were listening to all their meetings on speaker, but we were still having all our meetings at our desks.

I would constantly hear people around the cube farm stumbling through sentences because they could hear themselves through a neighbors computer with a slight delay.

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moezd
2 hours ago
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Yes, and you can also write two different sentences using two different pens in your hands.
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jvvw
2 hours ago
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When my son was about 4 or 5 he used to draw pictures with pens in both hands simultaneously which I was always amazed he could do!
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markdown
2 hours ago
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When I was an infant I'd waddle through my mothers garden to my favourite fruit tree... a chilly bush. I'd pick the red chillies and eat them with gusto. My mouth would turn red but that didn't bother me. These were very hot chillies that my parents couldn't eat even when they were green.

Sadly, I lost that super power at some point. I love a spicy curry, but I don't think I'd make it through a Hot Ones episode as a guest.

Does your son still have his ability?

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xamuel
53 minutes ago
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And you can subvocalize (that is, think them in your mind) two different voices at once if you deliberately try to, and it's a skill that gets easier with practice. Though, no matter how much I practiced it, I was never able to get to where it would take place automatically without my forcing it.
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runtime_lens
4 hours ago
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This makes me wonder how much of paying attention is really prioritization rather than filtering everything else out. We probably process far more than we're consciously aware of.
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Lomlioto
3 hours ago
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I def process more than I want.

Its def a spectrum.

In the easiest look at people like me who complain very quick if something is wrong like to warm to cold to sweaty etc. and others not even ackknowliding it at all

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noelwelsh
3 hours ago
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Absolutely. Take a look at "unconscious perception".
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londons_explore
3 hours ago
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Listening to two talkers at a time is certainly doable...

As is talking whilst listening to another conversation - eg. Giving a lecture whilst eves dropping on the people talking at the back of the lecture theatre.

However, having a two way conversation with one person whilst listening to another is really hard.

Not sure why.

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MomsAVoxell
2 hours ago
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I'm a native English speaking pinball freak living as an expat in a German-speaking country, and I find myself often listening to English speakers on the train, while also carrying on a conversation in German .. and I have observed that the same part of my mind that can handle multi ball-pinball events, where during a pinball session multiple balls are in play, 'feels' active.

Its a kind of context juggling mechanism in both cases, and it feels like the same mental muscle being exercised in both cases.

I wonder if there is a worthwhile experiment to be conducted wherein an EEG'ed pinball player gets to play pinball with easy multi ball targets, while also listening to German and English speakers, and then passing a test at the end of it .. because I sure have been preparing for that kind of scenario lately ..

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gleenn
3 hours ago
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Listening and responding are likely pretty different mental activities
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taneq
2 hours ago
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You're using one of the streams for yourself. :P
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alkyon
1 hour ago
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The same is true for music, otherwise canons and polyphony wouldn't work.
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thelastgallon
2 hours ago
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"humans have only one language processor" -- this is what I remember from Patrick Henry Winstons lecture
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coldtea
1 hour ago
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Async-programming style single-core concurrency would still look like parallelism to an outside observer :)
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latentframe
3 hours ago
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The simultaneous neural representation is very interesting result here
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vanderZwan
2 hours ago
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Come on guys, the contribution of the research is that it made measurements of how the processing of multiple inputs is represented in EEGs, not whether or not we can handle multiple inputs. Stop acting snarky, it just shows you didn't read beyond the headline.
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bitwize
48 minutes ago
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My wife's brain could probably do that. I'm not so sure about mine.
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broccoluvr
3 hours ago
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you guys telling me you still listening to only 1 podcast at the time?
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awestroke
4 hours ago
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This is maybe only tangentially relevant to the linked study, but I've noticed I can read aloud from a book on autopilot while thinking about other things or even thinking back on past conversations. I could not do this a few years ago, but now it happens on its own. I wonder how that relates to attention and speech streams
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Perz1val
3 hours ago
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Not reading out loud, but I've caught myself a few times on reading and not processing that, because I was thinking about something else. Like I still did the reading, but straight to /dev/null of my brain
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cevn
2 hours ago
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I think everyone does this. It reminds me of a possible related phenomenon. The act of remembering what you do takes a few extra brain cells, to enable the “recording function “. If you are on complete autopilot, doing a routine task, you will often forget to turn on the recording function. Like the other day I tried to remember whther I had run the dryer and realized it had been completely optimized out of my memory.
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topato
2 hours ago
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Welcome to a glimpse into the pathetic life [if one can even call it a life…] of a sad and wretched creature — the poor humans born with a deficiency of attention and an abundance of activity. This is a universal experience for the lost souls who stumble through life, burdened with a despicable and perverted simulacrum of a normal human’s brain, condemned with a condition more commonly known as…

The Dangerously Corrupted and Criminally Insane Mind of the ADHD Afflicted!

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m12k
4 hours ago
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I experienced this too, when I started reading out loud more. At first, it was just that my eyes would scan ahead a bit from what I was saying, to help me get the right emphasis by knowing where the sentence was going. It felt like I had "handed off" saying the words out loud to a "subroutine", so my attention could be on what I was reading. Then that "readahead" extended to a whole sentence. And at that point it was like I was so far ahead of what I was saying that I had time to think about it a bit. And then at some point it was like the "reading the words" part got handed off to a "subroutine" too, so my attention could mostly stay on whatever I was thinking
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surfsvammel
4 hours ago
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This is something that has been studied and is apparently more common when reading out loud. I have this as well. I can read to my kids and at the same time plan the upcoming day. Pretty neat!
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baxtr
3 hours ago
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Sometimes I read a book out loud and think about something completely different.

I wonder if reading aloud might be like walking. I can be walking and speaking to a person at the same time.

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j45
3 hours ago
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The DJ is explained.
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thenthenthen
2 hours ago
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Many dj mixers offer the option to split the main mix to one ear and the cue’d track to the other, i have never been able to mix like that, only with cue on headphones and main mix out in the room/monitors. Weird
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throwawaysjskdk
2 hours ago
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yep, my wife does this routinely
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skor
4 hours ago
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parents tend to yell at the same time and it needs simultaneous processing
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vanderZwan
2 hours ago
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Your example is needlessly bleak, but in general: yes, we're a social species and being able to process multiple speech streams seems obviously pretty important in many social contexts involving more than two people.
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eurekin
4 hours ago
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Also explains why we like music with two simultaneous distinct sections (bass + the rest). One without the other doesn't feel as complete
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junon
3 hours ago
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This is a completely different phenomenon. Your ear/brain are tuned to rhythmic beats in the lower frequencies (footsteps). We're better at pattern recognition with the lower frequencies.

Also, our brains will encode the differences in registers to evoke emotion differently, which is often used by horror films to make a scene scarier[0]. Evolutionarily this is probably to detect screams or babies crying, a rustling bush, etc.

Speech encoding, at least per this article, has little to do with that. We don't have music encoding so much as we have pattern recognition, instinctual emotional respond to sound, etc.

Another great video about how music is perceived in animals is [1], just while we're on the topic.

[0] https://www.atlasobscura.com/articles/how-the-hidden-sounds-...

[1] https://youtu.be/0ZYhyewNQMo?is=0mWSRAzObOD2p32E

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jimbob45
2 hours ago
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If you can listen to someone play the piano with two hands, it’s a short hop to get to speech.
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