2 Hz binaural beats
The slowest setting most people use, and the one you are meant to stop noticing. Two cycles a second is slow enough that it reads as swelling rather than pulsing.
2 Hz sits in the middle of the delta band, the slowest range in common use. Over a low carrier it is close to inaudible as a rhythm — what you notice is a very slow swell every half second, which is why it is the standard choice for sleep and the wrong choice for anything you need to stay awake for.
Why 2 Hz rather than 1 or 4
- Below about 1.5 Hz the swell is so slow that most people cannot perceive it at all. Nothing is wrong with that, but you are then listening to a plain tone.
- Above about 3 Hz the movement becomes noticeable enough to follow, which is the opposite of what a sleep sound should do.
- 2 Hz is the compromise most sleep presets land on, here and elsewhere. It is a convention rather than a finding.
Use a low carrier
The default here is 100 Hz, lower than the 200 Hz used on daytime pages. Low carriers are less fatiguing across a whole night and they sit underneath a noise bed rather than on top of it. Above roughly 300 Hz a 2 Hz beat also gets harder to perceive, so a high carrier gives you a bright tone and less of the effect you came for.
What to expect over eight hours
Very little, deliberately. The session fades out over the last eight seconds instead of stopping, so a timer that ends at 5 a.m. does not wake you. If you sleep with headphones, flat sleep headphones or a headband are far more comfortable than earbuds; if you cannot, run the brown noise generator from a speaker instead — the noise bed works without headphones even though the beat does not.
If you cannot sleep without sound at all, that is worth raising with a doctor rather than solving with a longer timer. Insomnia has treatments that work; a tone generator is a comfort measure. See safety.
Questions
Is 2 Hz good for deep sleep?
It is the conventional choice for sleep sessions. Whether a delta beat improves sleep depth is not established — the masking effect of a steady sound is the better-supported half.
Should the carrier be low for 2 Hz?
Yes, roughly 80–150 Hz. Low carriers are easier over long sessions and make the slow beat easier to perceive.
Can I run it all night?
Yes, at a low volume. The timer goes to eight hours and fades rather than cutting.
Why can I barely notice the beat?
That is the intended behaviour at this rate. If you want to hear the rhythm clearly, try 6 Hz or 10 Hz.
Running this on a phone? The Brainwave Generator app keeps playing with the screen off, works without a connection, and carries the same engine. Free on iOS and Android.