In its simplest form, it's a Sony Walkman-like device sitting on the desk in front of me. In a day and age in which music players are at most the dimensions of a deck of playing cards, and maybe 10 cards thick, it's charmingly retro. Retro in a "looking back at the future, according to 80s sci-fi". Or seeing space cults walk out into the public arena wearing 70s-era meditation robes which are supposed to be "spacey".The aesthetic betrays the late 80s, very early 90s zippie boho culture that engendered it - mirrored sunglasses, attached by a headphone cable to the top, headphones attached on the side, with a clunky LED display on the front. Very Max Headroom, baby.
Some clever cove realized that you could actually interfere with a brainwave pattern by putting a frequency into the eyes and/or ears. Either by design, or by accident, as the French found out when they planted trees at regulated intervals on either side of the autoroute, meaning that when a particular stretch of road was driven at the legal speed, the strobing effect of the trees had a calming influence which led to crashes. So another clever cove decided to figure out which frequencies cause which brainwave changes, and build something which will strobe at those frequencies. Or better yet, take you through a sequence of strobes, ramping through different states to achieve different ends.
So the idea with this device is, you put the mirrorshades over your eyes, and the headphones on your ears, and the machine flashes strobing lights into each eye, one at a time (albeit very rapidly), and binaural beats into each ear. Depending on the pattern you select, it either ramps down the frequencies on both for calming and relaxation, or ramps them up to induce mental alertness, or goes through a crazy set of "meditation" frequencies heavy in deltas and gammas in order to be almost "trippy".
In practice, you're sitting with this dorky New Age thing on your face, listening to a sine wave.
You do pass through several phases, though:
1) The "I can't believe I'm doing this" phase. I mean, the device looks like something you picked up at a garage sale and is blipping chiptune type sine wave tones into each ear. You've also got strobing blue or red lights into each eye. It's a visual and sonic assault, and your brain tries to process it. And you first go "okay, here I am with what amounts to a strobe light and a very rapid metronome."
2) The "okay, I'm calming down here and letting it do its thing" phase. You stop trying to follow what's going on and relax into it, the same way in which you dip the testicular parts of you into a hot spring or a cold swimming pool - very deliberately, and then oh, hey, it's forgotten about. There can be some vertigo, some head-spinning feelings, or a stomach-drop sensation.
3) The "something's going on" phase - you are getting calmer. You're mindful of your breath (or, if it's energising, you want to rip the damn thing off your face and get on with it)
4) The "okay, now something's really going on" phase. Because even though you're seeing (through closed eyes) a strobing blue light, the next thing you know you're seeing impossible things like rainbow colors, prismatic effects, firework effects and so forth. You start seeing and hearing things and thinking things you weren't before.
5) The "hey wait, it just faded out" - or you wake up a while later and realize you never noticed when it stopped.
It's almost like going into that weird smelling health food store, and finding a delightfully hippie-looking label for some horehound and brown rice syrup lozenge for your sore throat, feeling like you should be going home and baking lentils on your avocado-colored kitchen appliances when you realize my God, this stuff actually works.
The simplest ones come with 20 to 30 "programs" which run the gamut of enhanced learning to mediation to calming to energizing. Spend a lot of money and you can program them by computer, or they resemble rack-mounted effects boxes rather than small-factor Walkman boxes. The latest thing is being able to sync it up to CDs with encoded strobe information, so you're not restricted to a computer bloop but can listen to encoded music, which can be far more interesting to listen to. The simplest machines come with blue or red glasses, but more sophisticated ones have multiple color lights in the glasses. Unfortunately, no amount of money will get you past something that is obviously completely New Agey and completely retro-geeky.
There are some contraindictions: please make sure you're not one of those who goes into violent seizures when watching Japanese TV shows or strobe lights - because if you are one of those people, you're going to have a Bad Time.
But if you're up for the challenge, it can be a nice way to push your brain into different brainwave states without having to spend time hanging from hooks in some circus sideshow, or chanting "om mani padme hum" for hours on end. Whether it actually has all of the promised effects of enhanced learning or is simply a freaky way to spend 20 to 30 minutes, it's certainly been my cup of tea. They're cheap enough on eBay to be worth the $100.