What Are Binaural Beats?
A binaural beat is not a sound you can record. It appears inside the listener. Feed the left ear a steady 200 Hz sine wave and the right ear 207 Hz, and the auditory system — reconciling two tones that will not agree — produces a slow pulsing at the 7 Hz difference between them.
Because the effect is created by the brain combining two separate signals, it only works when each ear receives its own tone. Headphones are essential. Over loudspeakers the two waves mix in the air on their way to you, and what you hear is an ordinary acoustic beat instead.
Beat Frequencies and Brainwave Bands
Beat rates are usually described using the same names given to bands of brainwave activity. This generator shows the current band beside the beat control.
Delta
under 4 Hz
The slowest setting — a deep, barely-moving pulse. Associated with deep sleep and used as a night-time backdrop.
Theta
4 – 8 Hz
A gentle, drifting rhythm linked to meditation, drowsiness, and creative reverie. A good starting point.
Alpha
8 – 13 Hz
A clear, steady flutter associated with relaxed, alert focus — calm attention rather than sleepiness.
Beta & Gamma
13 Hz and above
Fast enough that the beat starts to sound like roughness or texture. Associated with alertness and active concentration.
Claims about brainwave entrainment are still debated in the research literature. Treat the bands as a map of how the sound feels rather than a guarantee of what it does.
Locking the Two Ears Together
Both tones have their own slider and tune freely. Set a few hertz between them and you get a binaural beat; set them far apart and you get something else entirely — a drone split across the stereo field, with one pitch anchored in each ear.
Once you have found a relationship you like, the lock holds it while you move. Press it once and the hertz gap is held: a left tone at 40 Hz with the right at 80 Hz stays 40 Hz apart, so sliding the left up to 80 Hz carries the right to 120 Hz. Press it again and the ratio is held instead: the same pair is locked at 2×, so sliding the left to 80 Hz carries the right to 160 Hz and the musical distance between the ears never changes as you sweep. Press a third time to unlock.
Holding the gap keeps the beat rate constant while the pitch moves. Holding the ratio keeps the harmony constant while the beat rate scales with it. The difference control still adds its own offset on top of either.
The Pink Noise Layer
Pure sine waves are clinical. Long sessions can feel sterile, and the tones sit very exposed in the ear. The optional pink noise bed gives them something to rest on.
The noise is true pink — falling at 3 dB per octave — and then runs through two cascaded Moog-style ladder filters, the same filter design used by the pink noise generator. Resonance is deliberately held low so the bed stays smooth and never whistles, and both cutoff frequencies are yours to set. Pull them down for a dark, distant rumble; open them up for an airy hiss around the tones.
Stereo runs two independent noise generators, one per ear, for a wide and enveloping bed. Mono sends the same noise to both ears, which sits compactly in the centre of the image and leaves the sides clear for the tones.
How to Use This Binaural Beats Generator
Put on headphones and press Listen. Everything is generated live in your browser — nothing is downloaded or streamed.
- Volume — Overall loudness. Keep it low; sine waves at high volume are fatiguing.
- Left pitch — The carrier tone in your left ear, from 30 Hz to 800 Hz. Somewhere between 100 and 300 Hz is comfortable for long listening.
- Right pitch — The tone in your right ear, tuned freely over the same range.
- Lock ears — Holds the two tones in the relationship they are already in. One press holds the hertz gap, a second holds the ratio, a third unlocks.
- Beat — The offset in hertz added to the right tone. This is the binaural beat itself, and the band name beside it updates as you move.
- Tone level — Balance of the sine waves against the noise bed.
- Pink noise — Switch the noise layer on, choose mono or stereo width, and set both filter cutoffs.
- LFO — Each section has its own amplitude LFO. Rate sets how fast it breathes, depth how far it swings. The tone LFO moves both sine waves together so the beat stays intact.
Frequently Asked Questions
Do I really need headphones?
Yes. Over speakers the two tones mix acoustically before they reach your ears, which produces an ordinary beating tone rather than a binaural one. Any stereo headphones or earbuds will do — they do not need to be expensive.
What beat frequency should I start with?
Around 7 Hz, in the theta band, is a common starting point for relaxation and meditation. Move down towards delta for sleep, or up into alpha for relaxed focus. Adjust until the pulse feels comfortable rather than chasing a specific number.
Why does a wide gap stop sounding like a beat?
A binaural beat needs the two tones close together — roughly within 30 Hz. Wider than that, the ear hears two separate pitches instead of one pulsing tone. That is still a lovely thing to listen to, which is why both tones are tunable across the full range, but it is a stereo drone rather than a binaural beat.
Are binaural beats safe?
For most people, at moderate volume, yes. People with epilepsy should be cautious with rhythmic audio stimulation, and anyone with a medical concern should speak to a doctor. Do not listen while driving or operating machinery.
Does this work on mobile?
Yes. It runs in any modern browser on iOS, Android, and desktop using the Web Audio API. Plug in headphones or connect a pair over Bluetooth and press Listen.
Is this free?
Completely free, no account required. Listen to Noise is an independent project and every generator runs entirely in your browser.