20 Hz binaural beats
Fast beta, and the point where a binaural beat stops being ambient. Useful in short bursts; a poor choice for anything you want to forget is playing.
At 20 Hz the beat is fast enough that most listeners hear it as a continuous roughness rather than a pulse. That makes it the boundary of what is comfortable as background: fine for a twenty-minute push, tiring across an afternoon.
When 20 Hz is the right call
- A short, deliberate block where you want the sound to feel like effort.
- Waking up a dull afternoon — twenty minutes, then step down to 14 Hz or off.
- Testing your setup. Fast beats are the easiest to hear, so if you are not sure the effect is reaching you, this rate makes it obvious — although the headphone test is the proper check.
When it is the wrong call: sleep, meditation, reading, anything longer than about half an hour, and any situation where you want to stop noticing the sound.
Lower the carrier if it grates
A fast beat over a high carrier is the harshest combination this generator makes. Dropping the carrier to 150–200 Hz softens it considerably, and a brown noise bed underneath does the rest — that is the second preset.
Above 20 Hz
The next commonly used rate is 40 Hz, which is a different kind of sound again: a continuous flutter with its own page and its own much-misquoted research story. Between the two there is little demand and no evidence for anything specific.
Questions
What is 20 Hz used for?
Short high-alertness blocks. It is the fastest rate most people find usable outside the gamma range.
Why does 20 Hz sound rough?
The beat is fast enough to be perceived as texture rather than as separate pulses — an ordinary feature of hearing, not a fault.
Can I sleep with 20 Hz?
No sensible reason to. Use a delta rate — the sleep player defaults to 2 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.