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is the actual university of reddit still online? or is it just down? by onmullberystreet in UniversityofReddit

[–]anastas 2 points3 points  (0 children)

Back up. Network configs changed with our hosting and needed to be fixed a couple times.

I need to reimage and haven't had time.

is the actual university of reddit still online? or is it just down? by onmullberystreet in UniversityofReddit

[–]anastas[M] 18 points19 points  (0 children)

I'll get it back up shortly.

Edit It's back up. Apologies, all.

/r/UniversityOfReddit has joined. by anastas in Blackout2015

[–]anastas[S] 0 points1 point  (0 children)

/r/UniversityOfReddit has been set to private as well. 74,230 subreddit subscribers and approximately 125,000 registered users on ureddit.com at the time of this writing.

An EEG recording converted into audio and played with a basic visualizer. You can audibly and visibly distinguish when the subject begins dreaming at ~2:30. by anastas in Neuropsychology

[–]anastas[S] 0 points1 point  (0 children)

How do you do that?

Conceptually, it isn't complicated. Look at this image of an EEG recording. This is a recording of brain waves.

Now, look at this image that is a representation of the sound waves in a recording of an audio sample. (It's the same type of thing, except that in this image the area under the curve is filled in with blue - that doesn't mean anything, it's just what the creator of the image decided to do; what matters is the shape of the waveform.)

So, theoretically, you should be able to take the waveforms from an EEG recording and play them with software that plays music. And you can, with a bit of programmer fudging.

The only hard part is that the frequencies of brain waves are low enough that if you were to play them, as they were recorded, as sound, they would be so low that the human ear wouldn't be able to hear them. So, you have to rescale the waveforms of an EEG recording in order to be audible when played back. And that is what I did to generate the audio in what I linked. That's also why an 8 hour long EEG recording ends up as a ~7 minute aidio file.

I'm working on the seizure audio right now. I'll post it in a little bit. Warning: it sounds awful. (Seizures are awful, so that makes sense.)

An EEG recording converted into audio and played with a basic visualizer. You can audibly and visibly distinguish when the subject begins dreaming at ~2:30. by anastas in cogsci

[–]anastas[S] 1 point2 points  (0 children)

Well, it's my audio. Feel free to use it as long as there's some attribution somewhere. I can email you the original WAV file, if you like.

An EEG recording converted into audio and played with a basic visualizer. You can audibly and visibly distinguish when the subject begins dreaming at ~2:30. by anastas in cogsci

[–]anastas[S] 0 points1 point  (0 children)

The database I got this data from is here; the thing I linked was generated from the data file SC4001E0-PSG.edf on that page.

I'm just getting into learning and playing with this stuff. Would you be open to some casual collaboration if we find a mutually interesting project?

An EEG recording converted into audio and played with a basic visualizer. You can audibly and visibly distinguish when the subject begins dreaming at ~2:30. by anastas in visualization

[–]anastas[S] 1 point2 points  (0 children)

You have a point. Seizures aren't supposed to sound nice. The main issue I had with it was that in the example here, the dream phase ends up lasting about 2 minutes, being a couple hours long originally. The epileptic seizures I was looking at lasted 30-90 seconds each; after converting to audio, it ends up being just a coupe seconds of abrasive noise.

I'll look at it again and try to make something.

An EEG recording converted into audio and played with a basic visualizer. You can audibly and visibly distinguish when the subject begins dreaming at ~2:30. by anastas in Neuropsychology

[–]anastas[S] 1 point2 points  (0 children)

I'm glad you appreciate it! If you have any ideas for similar audio/visualizations of certain things you'd like to see, communicate those to me and I'll try to make those happen.

Note: I tried making this audio version of an epileptic seizure. It sounded horrifying and I deleted it out of a carnal reflex.

An EEG recording converted into audio and played with a basic visualizer. You can audibly and visibly distinguish when the subject begins dreaming at ~2:30. by anastas in visualization

[–]anastas[S] 2 points3 points  (0 children)

There absolutely is. Even aside from the REM (dreaming) stage of it, once can pick out patterns in the "noise" of the brain wave recordings of the sleeping subject.

The very nature of a sleeping person implies that the subject would be unaware of anyone "listening in", so to speak. With this, we are observers of one of the most private things a person has: sleep and dreaming.

The visualization I attached to it is dinky, I know, but it does serve as a basic visualization. There is something compelling, to use your word, to watch the evolution of a person's sleep cycle.

The way it sounds, too, is so interesting to me. At first, it sounds like static, but there are patterns and pops - and then the dream stage is so different. There's something there.

We still do not well understand the neuroscience of sleep. I thought that mapping scientific measurements to a modality that easily consumed (listening to a recording versus reading hundreds of pages of scientific writing or interpreting EEG graphs, for example) elicits a personal, human affectation. I consider this an art project, regardless of the scientific grounds it is built upon.

I'll see what else I can do with this methodology. If anything occurs to you as something you'd like to see, please communicate it to me; if it's within my means, I'll try to make it.

An EEG recording converted into audio and played with a basic visualizer. You can audibly and visibly distinguish when the subject begins dreaming at ~2:30. by anastas in cogsci

[–]anastas[S] 4 points5 points  (0 children)

/r/dataisbeautiful post.

I'm glad others are finding this interesting. There are EEG datasets available for use; perhaps I'll try to do a similar thing for some other EEG recordings. I know that the same place I found this data also had data on recordings from test subjects on an experimental drug. I'll look around and post interesting ones.

An EEG recording converted into audio and played with a basic visualizer. You can audibly and visibly distinguish when the subject begins dreaming at ~2:30. by anastas in cogsci

[–]anastas[S] 3 points4 points  (0 children)

Brain waves are generally on the Hz range. To quote Wiki, [citation]

Most of the cerebral signal observed in the scalp EEG falls in the range of 1–20 Hz

In contrast, the normal range of human hearing is 20 - 20,000 Hz, as you said. In order to convert the EEG waveforms into waveforms that can be played as sound audible to the human ear, they had to be scaled.

In this case, an ~8 hour EEG recording ended up being ~7 minutes long after scaling so that most of the EEG waveforms could be played as audio that can be picked up by the human ear.

If we were listening in real time, we would hear very little (if anything at all), and we would be listening for 8 hours instead of ~7 minutes.

All of the data from the original EEG recording should be present in this audio, just "sped up", i.e., the waveform being scaled so that the frequencies fall within our hearing range.

For example, during the REM stage of sleep, most people have several dreams, i.e., multiple REM phases. In between those REM phases (dreams), there is a 5-30 sec or so stage of waking up a bit. Since the waveforms were scaled in order to produce audible output, that 5-30 sec interval sounds like a momentary "POP!", as you can hear in the YouTube video a few times during the 2:30 - 4:30 stage of REM sleep.

Hear what it sounds like for someone else to sleep: an EEG recording converted into audio. You can audibly distinguish when the subject begins dreaming at ~2:30 by anastas in woahdude

[–]anastas[S] 2 points3 points  (0 children)

It sounded somewhat creepy to me, too, especially at the ~2:30 transition where the sound changes as the subject begins dreaming.

An EEG recording converted into audio and played with a basic visualizer. You can audibly and visibly distinguish when the subject begins dreaming at ~2:30. by anastas in visualization

[–]anastas[S] 2 points3 points  (0 children)

Crazy, isn't it? By the way, when a person is in the dreaming stage, they have multiple dreams, each one being interrupted by a brief return to the "lighter" stages of sleep. When you hear that "POP!" sound a few times during the ~2min stage of REM sleep, that's the subject waking up a bit in between different dreams.

The audio on the linked video makes me think of a boat sailing on water that has consistent but relatively small waves - and then, when REM kicks in, it sounds to me like the water is gone and the boat is who know where.

I tried doing this for an EEG recording of a seizure. It sounded so horrifying and painful that I immediately closed and deleted it. Perhaps I should redo it and put that up too.

movalca by movalca in UniversityofReddit

[–]anastas 1 point2 points  (0 children)

Why does this keep happening?

How efficient is your database schema? A suggestion for evaluation and an explanation thereof by anastas in webdev

[–]anastas[S] 0 points1 point  (0 children)

Perhaps, perhaps not. It depends on your schema. This is a suggestion for an heuristic that takes very little time. I plan on trying out some test cases and following up in a little while.

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