Binaural Beats Generator

Binaural beats are made by playing two slightly different tones, one in each ear: with 195 Hz on the left and 205 Hz on the right, the brain perceives a slow 10 Hz pulsing that is not in either sound. This generator makes such tracks as MP3 or WAV files of up to an hour, or plays them live, with an optional soft pink or brown noise underneath. You choose the carrier pitch, the beat rate and the levels; the files are made on your device.

How to use this tool

1. Choose a beat (2–40 Hz) or enter your own, and a carrier pitch (200 Hz is a good start).
2. Optionally add pink or brown noise and set its level.
3. Set the length and the fades, then press Calculate to make the file or to start live playback.
4. Listen with headphones at a low volume.

Formula

Left = carrier − beat ÷ 2 · Right = carrier + beat ÷ 2 · beat = right − left

Each ear gets a pure sine tone; the tones are computed sample by sample, so the frequencies are exact. The level is the peak of each tone (−20 dBFS by default). Pink noise uses Paul Kellet's filter and brown noise a leaky integrator, each independent in the two ears and set to an exact RMS level. MP3 files of up to 10 minutes are encoded with LAME in your browser, block by block; longer ones are generated and encoded by the ffmpeg engine (about 30 MB, downloaded once), which is several times faster. The band names (delta, theta, alpha, beta, gamma) are the conventional EEG names for those rates, nothing more.

Example

With a 200 Hz carrier and a 10 Hz beat, the left ear hears 195 Hz and the right ear 205 Hz. A 10-minute stereo MP3 at 128 kbps is about 128,000 ÷ 8 × 600 = 9.6 MB; the same length as a WAV would be 44,100 × 4 × 600 ≈ 106 MB.