Hear the difference

Both of these are generated in your browser as you listen. Nothing is downloaded and nothing is recorded.

One sits still in the middle of your head and pulses. The other travels from ear to ear. Written down they can sound similar. Played one after the other they are not remotely alike, which is the point of putting them here.

Quick check before you listen

Both of these depend on your ears getting different signals, and this page has no way of telling whether yours are. No browser gives a website that. Ten seconds by ear is more reliable than anything we could claim to measure.

Play a sound panned hard left. Is it only in your left ear?
Repeat on the right.

Both ears, or centred: Your channels are being summed. Check mono audio, and check you are not on speakers.
Wrong side both times: Headphones are on backwards. Harmless, but now you know.
Mostly one side both times: Check your balance slider.

Hear the difference

Headphones on. Play one, then the other. The distinction usually lands in a couple of seconds, which is faster than any amount of description.

This demo needs JavaScript. Everything else on the site reads fine without it.

What you are actually hearing

The binaural preset plays 400 Hz in one ear and 406 Hz in the other, continuously and at the same time. The 6 Hz pulse you hear is not in either tone. Your hearing makes it out of the pair.

The bilateral preset uses those same two tones, 400 Hz and 406 Hz, at the same pitches. The only difference is that they take turns instead of sounding together.

That is worth sitting with for a second. Identical tones, identical pitches, completely different experience, and no binaural beat in the second one at all. Two detuned tones do not make a binaural beat. Two simultaneous detuned tones do.

It is also exactly why so many tracks are mixed up with each other. On paper the two recipes look the same. Telling them apart takes about ten seconds once you know what to listen for.