Binaural beats
Two steady tones a few hertz apart, one in each ear. The pulsing you hear is produced by your own auditory system comparing them, which is why this is the one thing on the site that does not work through speakers.
How a binaural beat is made
Play 195 Hz into the left ear and 205 Hz into the right. Neither tone pulses. What you hear is a 10 Hz throb, and it is not present in the air — it appears where the two signals are first compared, in the superior olivary complex of the brainstem, which is the structure that normally uses tiny timing differences between the ears to work out which direction a sound came from. The beat is a by-product of that machinery being handed two signals it cannot reconcile.
This is a different phenomenon from an ordinary acoustic beat, which happens in the air when two nearby frequencies from the same source add and cancel. Acoustic beats are physically present in the waveform and a microphone records them. Binaural beats are not and it does not. That distinction is why headphones are a requirement rather than a recommendation: through speakers the two tones mix before they reach you and you hear the ordinary version instead.
The generator here defaults to a 200 Hz carrier and lets the beat rate vary. Both are bounded for good reasons. Above about 1 kHz the effect weakens sharply, because the auditory system switches from timing differences to level differences for locating sound; the classic literature uses carriers from 200 to 500 Hz. And beyond roughly 30 to 40 Hz of separation the two tones stop fusing and you hear a chord instead of a pulse, so a "100 Hz binaural beat" is not one.
What the evidence supports, and what it does not
The popular claim is entrainment: that listening to a beat in the alpha range drives cortical rhythms towards alpha, and that this produces the state alpha is associated with. The honest summary is that this is weakly evidenced. Studies are typically small, use varied protocols and exposure times, measure different outcomes, and produce inconsistent results; meta-analyses report small pooled effects with heterogeneity high enough to make the pooling questionable, and the field has the publication-bias profile you would expect where positive results are more interesting than null ones. Some careful work finds no reliable change in EEG at all.
None of that makes the experience fake. People do report feeling calmer, and there are unglamorous explanations available that nobody should be embarrassed by: sitting still with headphones on for twenty minutes is itself relaxing, expectation is powerful, and a low steady tone is pleasant. If it helps you, it helps you — the question this section addresses is only whether the mechanism advertised is the mechanism operating, and the answer is that we do not know and current evidence is not strong.
What this site will not do is attach the names of EEG bands to promised states and leave it there. The band names in the selector are labels for frequency ranges, nothing more: choosing "alpha" selects a 10 Hz beat because 10 Hz is in the alpha range, not because it will put you into one. Nothing here is health advice, and anyone with epilepsy or a seizure history should be aware that rhythmic audio and visual stimulation is something to raise with a professional rather than to experiment with.
The band names and the tones behind them
Left and right channel frequencies at a 200 Hz carrier, computed by the generator. The band names describe EEG frequency ranges — selecting one chooses a beat rate in that range and nothing else follows from it.
| Band | EEG range | Left / right tone | Associated in the literature with |
|---|---|---|---|
| Delta | 0.5–4 Hz | 199 / 201 Hz | deep sleep |
| Theta | 4–8 Hz | 197 / 203 Hz | drowsiness and light sleep |
| Alpha | 8–13 Hz | 195 / 205 Hz | relaxed wakefulness |
| Beta | 13–30 Hz | 191 / 209 Hz | alert, active thinking |
| Gamma | 30–40 Hz | 182.5 / 217.5 Hz | high-frequency cortical activity |
"Associated with" means researchers observe that rhythm in those states. It does not mean listening to a beat at that rate produces the state, and the evidence that it does is weak. Carrier and beat are bounded to 80–1000 Hz and 0.5–40 Hz.
Common questions
Do binaural beats work through speakers?
No. The effect depends on each ear receiving a different frequency, and through speakers the two tones mix in the air before they reach you. You then hear an ordinary acoustic beat, which is a different thing produced in a different place.
Which beat frequency should I choose?
There is no evidence-based answer, so choose by ear. Lower rates around 4 to 6 Hz feel slower and are the usual choice for winding down; 10 Hz is the most commonly used setting overall. Trying a few for a minute each is more useful than any chart.
Why is the carrier limited to 80 to 1000 Hz?
Below that range headphones roll off and the ear localises poorly; above it the effect weakens sharply, because the auditory system stops relying on timing differences between the ears. The research that exists mostly uses carriers between 200 and 500 Hz.