Comment by twofornone | Hacker News Reader

Comment by twofornone | Hacker News Reader

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I want to be excited, but the blinking and chewing signals demonstrated in the paper are not true EEG signals, they are muscular artifacts. Based on my own experiments with OpenBCI[0], specifically the cython board and the ultracortex with spike electrodes, this paper does not demonstrate the most difficult part, measuring actual brain generated EEG signals.

I could not separate any signal out from the noise, neither with the provided software (which ostensibly filters and bins alpha, theta, beta, and gamma waves), nor while trying to roll my own filtering. That's not to say that this isn't good work, but I think the real difficulty is in the electrode hardware. I suspect that passive electrodes are unlikely to be very useful for the hobbyist, at least not at consumer level prices, which are still quite high. Maybe there was just something unlucky about my hair/scalp, but even the ostensibly simple closed eye alpha signal eluded my measurement attempts.

It's been a year or two, I haven't kept up if there have been developments, open to suggestions! I don't trust myself to build active electrodes, a reasonably priced kit would be awesome.

0. https://openbci.com/

Re: muscular artefacts, can anyone elucidate the nature of "pre-speech signals" captured by electrodes along the jaw? There was a MIT student a few years ago who built a headset shaped device that could hear his thoughts because it picked up his "inner voice" via electrodes on his face. My understanding is that the signals are the same as those produced in speech, but weaker (below the threshold of actually activating the muscle).

Edit: https://www.media.mit.edu/posts/arnav-kapur-wins-use-it-leme...

>"The headset-like device, AlterEgo, is a sensory and auditory feedback system that uses neuromuscular signals from the brain’s speech system to extract speech. When we talk to ourselves internally, our brain transmits electrical signals to the vocal cords and internal muscles involved in speech production. With AlterEgo, an artificial intelligence agent is able to make sense of these signals and prepare a response. The user can hear the AI agent’s responses through vibrations in the skull and inner ear, thus making the process entirely internal. The AI agent can also send the information to a computer, to help an individual with a speech disability communicate in real-time."

In the GitHub you can find the dataset))) with recorded EEG signal

Ah you're right, they measure the closed eye alpha signal. I'm just skimming with ctl+f and didn't see it, did they mention specifically what electrodes they used for their measurements?

Idk, but the signal doesn't look like an alpha wave you'd get from a good EEG. The video on their repository doesn't seem to be using the normal electrode set, nor use the common procedure of applying the electrodes.

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