What are binaurals, and how do they work? Do they work? What should I expect?

If you've been into hypnosis for any appreciable length of time, you've probably heard of binaurals. You might've heard some explanations of what they are, and what they purport to do; but I think it's useful, sometimes, to revisit things that we typically treat as "basic" information. This will be largely from memory, so I might update later with references/citations or additional/corrected information.

To get a grasp on what a binaural tone is (and what it tries to do), we'll need to - at least casually - address brainwave entrainment first.

So what is that? When we look at brain activity, we can measure brainwaves - specific frequency oscillations associated with the functioning of the brain in various different states - using any of several means (electrocorticogram, electroencephalogram, magnetoencephalogram, and intracranial electroenecephalogram.) We can analyze what frequencies are more prevalent when a person is relaxed, or alert, or agitated; this has been done repeatedly, to generate conventional frequency "bands" (or ranges): delta (1-4 Hz) all the way up through high gamma (80-150 Hz.) The "resting" brain produces waves in each band, and the combination of them can be considered a functional measurement of a person's mental state.

Brainwave entrainment seeks to exploit these known frequencies to induce a desired mental state in the subject. How? Historically, this was done using flashes of bright lights at the targeted frequency ranges; in fact, this is similar in nature to what my "brainwave images" are. The brain has an observable tendency to mimic frequencies that it is exposed heavily to, and this mimicry can be used, in theory, to shift the dominant mental state in a subject. Delta and theta waves are common targets, since they are typically equated with sleep and trance states (or "enhanced suggestibility," depending on who is doing the study.)

But imagine we'd like to do the same thing with audio. Easy, right? Just spin up a tone at the frequency desired, and off we go...except human hearing has a range of 20 Hz - 20000 Hz, with the best sensitivity between 2k-5k Hz. Want a delta state? 1-4 Hz? Not happening with sound, unless the literal vibration of the skull will work (that's expected to be a strong "no".) And this is with modern stereo equipment; older speakers couldn't get below 40 Hz all that reliably. So what's the solution?

Enter binaural beats. Binaural? Both ears. Beats? This is referring to something that happens when you hear two tones that are of very similar, but not the same, frequencies; consider how a musician knows something to be out of tune. A beat is the perceived frequency gap between two sounds, and it's why binaurals all have that kind of rhythmic pulsing sensation: the "beat." When your brain processes these two tones, one in each ear, it generates an equivalent frequency to the "gap" between them. Now we have an audio solution for brainwave entrainment.

Or do we? Does it work? How well can the brain re-construct such small frequency gaps? How sensitive are a person's ears to those differences? Does the additional processing required to perceive the "beats" interfere with their efficacy?

That would be telling. Seriously, these are "experiments" for that exact reason. From a neuroscience perspective, there are -far- too many variables to study this effectively with current technology (at least without a substantial amount of funding.) Psychological studies suffer from the repeated issue of experimenter bias introducing error within the results - which is, of course, what I endeavor to avoid. How scientific am I really being? As much as I'm able, which is admittedly not very scientific; I lack the volume of feedback and the situational controls to really dig deep into the question of how effective binaurals actually are.

Without giving away too many of my secrets...the short answer is, as with many things adjacent to hypnosis: it depends on the subject. I have found some people to be extremely susceptible to binaurals, entering near-catatonic states from sufficient listening. I've encountered some subjects who experience a pleasant sensation, but otherwise seem unaffected. I've even met a few folks who just don't like the way it feels to listen. The best thing to do is to try them out for yourself.

I hope this serves as a helpful refresher, or provides you with some new information if this stuff interests you.

Now, to the experiments!

[Original post] It has been brought to my attention, thanks to a poll on Twitter, that a collection of my binaurals in playlist form might be highly enjoyable. So, I've compiled precisely such a thing.

The playlist contains my binaural experiments in ascending order, with the base tones omitted for the sake of avoiding excess repetition. Still, it'll last for several hours, so be mindful of your data if that's relevant.

Depending on how susceptible you are to binaurals, you may find yourself pretty incapacitated before very long. Don't say I didn't warn you.

Without further adieu: