Binaural beats



Binaural beats are an auditory illusion where two oscillators, slightly detuned from each other, are played simultaneously with one perceived by each ear. The human brain mixes the audio from each ear, and the listener perceives a "beating" effect that isn't actually there. This is a well-studied phenomenon that has gained the interest of audiologists and neurologists, but it's most famous for being picked up by the alternative medicine community as a way to get high.

What are binaural beats?
Binaural beats are an illusion produced by hearing two different frequencies in each ear. You can hear a binaural beat by playing two sine waves of close, but not the same, frequency into different earpieces of a set of headphones (not speakers!). The "beat" is heard as the brain tries to process them as a distinct sound, while taking into account the constructive/destructive interference. It is said to migrate brain waves to be closer to that frequency, like a sort of biological resonance, which current reseach can back up. Of course the same can be said for listening to relaxing music help you relax, up tempo music to help you feel energetic, etc...

This does not make your brain suddenly become "binaural", which doesn't make any sense.

Variants of binaural beats include "monaural beats" (which are no longer an auditory illusion, just interference in action) and "isochronic tones" (which are just regular beeps).

Pseudoscience claims
The I-Doser claims it can emulate prescription drug-like effects by listening to MP3's, to get stoned. This is largely a moral panic by parents who flunked science fueled by the eternal quest by teenagers to get stoned, and stupid ones convincing their friends it works. It is really more of wishful thinking and making yourself disoriented by playing discordant sounds really damn loud. If you want to experience it yourself, you can always listen to Bjork Captain Beefheart dubstep.

There was some research in the 1970s that claimed remission of drug dependency, increased relaxation, and reductions in pain while listening to binaural beats. This was also after training the brain in 30 minute increments in repeated sessions with biofeedback, basically self-hypnosis.

One of the more outrageous things about binaural beats is that you can pay for them... but it just takes one line in some free audio software to replicate the effect for yourself (these examples work for SuperCollider):

// basic 6 Hz beat { SinOsc.ar(200 + [0, 6], mul: 0.1) }.play;

// 10 Hz to 4 Hz over a 30 min period { SinOsc.ar(200 + [0, XLine.kr(10, 4, 60 * 30)], mul: 0.1) }.play;

// 7 Hz monaural beat { Pan2.ar(Mix(SinOsc.ar(200 + [0, 7])), 0.0, mul: 0.1) }.play;

// isochronic tone, 9 Hz to 4 Hz over 20 mins { LFPulse.ar(XLine.kr(9, 4, 60 * 20)).lag(0.001) * Pan2.ar(SinOsc.ar(200, mul: 0.1), 0.0) }.play;

If you prefer to use either Audacity or a program that generates such beats instead, see here or here respectively.

There. Easily $10 worth of beats, available for free only at RationalWiki.

The dangerous
As usual, one should never listen to sounds through headphones at high volumes (95 decibels or higher, or if one has to shout over the noise to be heard) and for sustained periods of time (depending on the decibels; 4 hours of 95 dB can damage the ears).

What does "binaural" mean, anyway?
Basically, "two ears." One usage of the word is "binaural recording," which is a form of stereo recording meant to take advantage of the spatial perception of the human ear. Recordings are usually done using a pair of microphones mounted to a dummy head with roughly accurate models of the human outer ear, and the result when played back through headphones is extremely realistic and comparable to surround sound, though following an entirely different recording model. Binaural recordings aren't woo at all, and have nothing to do with binaural beats.

You may recognize the "binaural recording" from ASMR, where the technique is often used. This explains why, if you search for "binaural" on YouTube, you get a mixture of two entirely different kinds of results: binaural beats and binaural ASMR recordings. It gets especially confusing in that there's some questionable and/or unexplored science surrounding each one.